City Council and Concurrent Authorities
February 4, 2025

2.2 HISTORICAL GROUNDWATER CONDITIONS
This section describes historical groundwater conditions in the Eastern San Joaquin Subbasin as of the development of the 2020 GSP. As such, this section includes both historical conditions in the Subbasin prior to 2019, and the current conditions as of the development of the 2020 GSP in 2019. These sections are maintained in the GSP to provide a context of the conditions occurring at the time the 2020 GSP was developed.

As required by the GSP regulations, the groundwater conditions section includes:
• Definition of current groundwater conditions in the Subbasin (as of 2020 GSP development) • Description of historical groundwater conditions in the Subbasin • Description of the distribution, availability (storage), and quality of groundwater • Identification of interactions between groundwater, surface water, groundwater dependent ecosystems, and subsidence
The groundwater conditions described in this section present the historical availability, quality, and distribution of groundwater which are the basis of this Plan’s sustainable management criteria and monitoring network. The current and historical conditions discussed are further expanded upon in Chapter 3: Sustainable Management Criteria and are used to define undesirable results and to establish measurable objectives, interim milestones, and minimum thresholds.

Historically, the two aspects of greatest focus for groundwater management in the Eastern San Joaquin Subbasin have been groundwater elevation and, in some areas of the Subbasin, groundwater quality. As discussed herein, a groundwater depression exists in the central portion of the Subbasin, while higher groundwater levels characterize the west portion of the Subbasin. Additionally, there are elevated levels of salinity and nitrate in some areas, along with naturally occurring constituents commonly seen throughout the Central Valley. Detailed descriptions of these conditions are provided in the following sections as part of a discussion of the historical and current conditions for each of the six sustainability indicators:
• Groundwater Elevation (Section 2.2.1)
• Groundwater Storage (Section 0)
• Seawater Intrusion (Section 0)
• Groundwater Quality (Section 2.2.4)
• Land Subsidence (Section 0)
• Interconnected Surface Water (Section 2.2.6)
Details of GDEs are provided in Section 2.2.7 and Section 2.3.7 to support the sustainability indicator discussions.

2.2.1 Groundwater Elevation
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2.2.1.1 Historical Groundwater Elevations
Data sources for groundwater elevation are abundant in the Eastern San Joaquin Subbasin. As discussed in Section 2.1, the CASGEM and San Joaquin County databases constitute the groundwater level data used for this analysis. These sources provide a robust dataset of groundwater levels going back to 1940.

To visually show long-term trends in groundwater elevations in the Eastern San Joaquin Subbasin, 10 wells that have periods-of-record greater than 40 years and that are relatively evenly distributed across the Subbasin were selected from available data (see Figure 2-42). Long-term hydrographs prepared for these wells show that, throughout most of the Eastern San Joaquin Subbasin, groundwater elevations have declined over time.

Average groundwater level decline was quantified for 1996-2015. In Section 2.3 (Water Budgets), the Historical Water Budget from the 2020 GSP uses 1996-2015 as a representative hydrologic period which includes an average annual precipitation of 14.7 inches, very close to the long-term average of 15.4 inches. The 1996-2015 period also includes the recent 2012-2015 drought, the wet years of 2010-2011, and periods of normal precipitation. Based on data from the 10 selected wells in Figure 2-42, the average groundwater level decline was -0.5 ft/year from 1996-2015.

Hydrographs for wells numbered #2, #5, and #6 show the largest decrease in groundwater elevation. These wells are located to the east of the City of Stockton. Hydrograph #9, which corresponds to a well located on the north edge of the Subbasin, shows the least decrease in groundwater elevation from 1996-2015. Hydrograph #4 corresponds with a well located in the western side of the Subbasin and is the only well to show an increasing trend in groundwater elevations. The northeast corner of the Subbasin is an area without a nearby representative hydrograph and was identified as a data gap in Section 2.1.10 (HCM Data Gaps).

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Figure 2-42: Hydrographs of Selected Wells
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Figure 2-43 shows the distribution of the groundwater elevations from the CASGEM and San Joaquin County databases compared to average precipitation in and near the Subbasin. Figure 2-43 shows an overall decreasing trend in groundwater elevation levels with larger variability over time. The increasing variability comes partly due to a larger number of wells being sampled through time in more varied topography, but also reflects the long-term changes in groundwater levels described above and in Figure 2-42.

Periods of increases in groundwater elevation moderately correspond to the amount of precipitation in the Eastern San Joaquin Subbasin. A correlating trend can be seen with groundwater elevation increases in several hydrographs in the early 1980s and late 1990s, associated with periods of high precipitation.

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Figure 2-43: Summary of Groundwater Elevation Data, 1940-2018

1. Each vertical bar in Figure 2-43 (a) represents the full range of groundwater level measurements recorded in a given year. The central gray box represents the middle 50% of measurements (ranging from the 25th percentile to the 75th percentile), with the horizontal line showing the median. The capped lines below and above the central box represent the minimum and maximum, respectively.

2. Precipitation monitoring depicted in Figure 2-43 (a) began in 1951.

3. The average annual precipitation line presented in Figure 2-43 (b) is based on an average of data collected at 7 stations which are mapped in Figure 2-44.
(b) Number of Groundwater Level Measurements
(a) Box-and-Whisker Plot with Precipitation
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Figure 2-44: Precipitation Stations

1. These stations are operated by California Irrigation Management Information System (CIMIS) (“A”), National Oceanic and Atmospheric Administration (NOAA) (“C”), and PestCast (University of California Statewide Integrated Pest Management Program [UC IPM] and Department of Pesticide Regulation [DPR]) (“P”).

Additionally, extensive reports and research examining the groundwater conditions of the Central Valley are available from a variety of sources, including the USGS and DWR. These documents supplement the water level data provided by the CASGEM and San Joaquin County databases and were used to assess current and historical groundwater elevations.

USGS Water Supply Paper 780 – One of the earliest discussions of measured groundwater levels in the Eastern San Joaquin Subbasin is the USGS Water Supply Paper 780. The report details river stage of the Mokelumne River and the surrounding groundwater table from roughly 1900 to 1930. Groundwater levels in wells around the Mokelumne River varied, but mostly declined due to an increase in groundwater pumping.

Even between years of minimal groundwater pumping, from 1927 to 1933, the water table decreased in elevation, most drastically in areas northeast and southeast of the City of Lodi (Piper et al., 1939).

DWR Bulletin 146 – DWR’s Bulletin 146 (1967) discusses water levels and flow directions in the 1960s and earlier, which provides added historical context to current groundwater conditions. Figures 4 and 5 of Bulletin 146 show groundwater elevation in most of the Eastern San Joaquin Subbasin in fall of 1950 and 1964, EXHIBIT 1
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respectively. Both maps show groundwater levels at the lowest elevation underneath the City of Stockton, which is attributed to heavy groundwater pumping. This groundwater depression is attributed as causing groundwater from the Delta to flow toward the City of Stockton and is described as having relatively worse water quality due to natural mineral salts. Barriers between the poorer quality water from the Delta and higher quality water from the Sierra Nevada Mountains noted in previous studies around the City of Stockton are not apparent (CA DWR, 1967).

Williamson, 1989 – Groundwater conditions provided in the groundwater model report by Williamson (1989) included horizontal and vertical flows. A westerly groundwater flow direction that roughly parallels the ground surface in the Eastern San Joaquin Subbasin was confirmed, as depicted on Figure 14 of that report.

Estimates of groundwater elevations for before-human-development were provided. Vertical flow characteristics before considerable human development were characterized and mapped; areas of wells that flowed without pumps are shown throughout the valley and in the western portion of the Eastern San Joaquin Subbasin. This is in contrast to current conditions, where wells flowing without pumps have not been currently observed in the Subbasin. At present, USGS nested monitoring wells confirm downward vertical flows (Williamson, 1989).

2.2.1.2 Conditions as of 2019: Groundwater Elevations
For the purposes of the 2020 GSP, current groundwater elevation conditions were characterized as first quarter 2017 (seasonal high, measured in spring 2017) and fourth quarter 2017 (seasonal low, measured in fall 2017) groundwater elevation measurements. At the time of the 2020 GSP, those records constituted the most complete dataset.

Groundwater elevations were mapped using the CASGEM dataset (including voluntarily monitored wells) and the San Joaquin County dataset.

Figure 2-45 and Figure 2-46 show the groundwater elevations for the first and fourth quarters of 2017, respectively. A pumping depression at the center of the Subbasin, east of the City of Stockton, existed during both of these periods. A localized pumping depression is shown expanding from the Cosumnes Subbasin across Dry Creek to the Eastern San Joaquin Subbasin in fourth quarter of 2017. However, from the perspective of the entire Eastern San Joaquin Subbasin, the central pumping depression to the east of the City of Stockton is most significant to achieving sustainability in the Subbasin. Groundwater generally flows from the outer edges of the Subbasin towards the depression in the middle of the Subbasin. Along the eastern side of the Subbasin, the lateral gradient of groundwater levels ranged from approximately 21 feet per mile (ft/mi) during the seasonal high to 16 ft/mi during the seasonal low. Along the western side of the Subbasin, the lateral gradient rangef from approximately 7 ft/mi during the seasonal high to 6 ft/mi during the seasonal low. The steeper gradients on the east side of the Subbasin compared to the west side are primarly due to the steeper topography in that area.

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Figure 2-45: First Quarter 2017 Groundwater Elevation
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Figure 2-46: Fourth Quarter 2017 Groundwater Levels
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2.2.1.2.1 Vertical Gradients
A vertical gradient drives the movement of groundwater perpendicular to the ground surface and is typically measured by comparing the elevations of groundwater in nested and/or clustered wells, wells with multiple completions at different depths. If groundwater elevations in the shallower completions are higher than in the deeper completions, the gradient is identified as a downward gradient. A downward gradient is one where groundwater is moving downward through the subsurface. If groundwater elevations in the shallower completions are lower than in the deeper completions, the gradient is identified as an upward gradient. An upward gradient is one where groundwater is moving upward through the subsurface. If groundwater elevations are the same throughout the completions, there is no vertical gradient.

Knowledge about vertical gradients is required by regulation and is useful for understanding how groundwater moves in the Subbasin.

Vertical flow characteristics before considerable human development are characterized and mapped by Williamson (1989), showing that wells flowing without pumps existed in the western portion of the Eastern San Joaquin Subbasin, also corresponding with areas of upward vertical gradients. This contrasts with current conditions, where wells flowing without pumps have not been currently observed in the Subbasin. At present, USGS nested monitoring wells confirm downward vertical gradients (Williamson, 1989).

As of the 2020 GSP, there were 16 nested and/or clustered well sites located in the Eastern San Joaquin Subbasin.

The locations of the wells are shown in Figure 2-47. The majority of these wells are located in the northwest portion of the Subbasin near the cities of Stockton and Lodi. Hydrographs with groundwater elevations for each respective set of nested wells are shown in Figure 2-48 through Figure 2-63. 10 out of 16 sets of wells consistently show elevations in shallower completions that are higher than in the deeper completions which indicates a downward gradient. The remaining six wells are located in the City of Lodi. Four of these wells exhibit a minimal downward gradient and two show no downward gradient.

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Figure 2-47: Map of Nested and/or Clustered Well Sites (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-48: Nested Well Hydrographs: CCWD 004-006 (as of 2020 GSP Development) Figure 2-49: Nested Well Hydrographs: CCWD 010-012 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-50: Nested Well Hydrographs: Sperry Well (as of 2020 GSP Development) Figure 2-51: Nested Well Hydrographs: Swenson Golf Course (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-52: Nested Well Hydrographs: STK-1 (as of 2020 GSP Development) Figure 2-53: Nested Well Hydrographs: STK-2 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-54: Nested Well Hydrographs: STK-4 (as of 2020 GSP Development) Figure 2-55: Nested Well Hydrographs: STK-5 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-56: Nested Well Hydrographs: STK-6 (as of 2020 GSP Development) Figure 2-57: Nested Well Hydrographs: STK-7 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-58: Nested Well Hydrographs: Lodi MW-21 (as of 2020 GSP Development) Figure 2-59: Nested Well Hydrographs: Lodi MW-24 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-60: Nested Well Hydrographs: Lodi MW-25 (as of 2020 GSP Development) Figure 2-61: Nested Well Hydrographs: Lodi SMW-1 (as of 2020 GSP Development) EXHIBIT 1
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Figure 2-62: Nested Well Hydrographs: Lodi WMW-1 (as of 2020 GSP Development) Figure 2-63: Nested Well Hydrographs: Lodi WMW-2 (as of 2020 GSP Development) EXHIBIT 1
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2.2.2 Groundwater Storage
The ESJWRM was used to estimate historical change in storage of the Eastern San Joaquin Subbasin from 1995-2023.

Figure 2-64 shows annual total storage for the combined ESJWRM Version 3.0 fresh groundwater layers (not including the deep saline layer). Figure 2-65 shows the cumulative change in storage against annual storage change and water year type. In 2015, the total fresh groundwater storage was estimated as 74.0 million acre-feet (MAF). An additional

95.0 MAF in the deepest simulated layer of the model (not pictured) is saline water. More information about the layers of the ESJWRM Version 3.0 and calculation of storage changes can be found in model documentation in Appendix 2- C.

Figure 2-64: Historical Modeled Change in Storage
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Figure 2-65: Historical Modeled Change in Annual Storage with Water Use and Year Type Notes:

1. Water Year Types based on San Joaquin Valley Water Year Index (CA DWR, 2024)

2. “Other Recharge” includes managed aquifer recharge, recharge from unlined canals and/or reservoirs, and recharge from ungauged watersheds.

3. “Change in Storage” is placed to balance the water budget. For instance, if annual outflows (-) are greater than inflows (+), there is a decrease in storage, but this would be shown on the positive side of the bar chart to balance out the increased outflows on the negative side of the bar chart.

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2.2.3 Seawater Intrusion
The Eastern San Joaquin Subbasin is not in a coastal area and seawater intrusion is not present. While the Delta ecosystem evolved with a natural salinity cycle that brought brackish tidal water in from the San Francisco Bay, levees installed to allow development of agriculture, followed by development and operation of the Central Valley Project and the State Water Project, have altered the inward movement of seawater through the Delta. Current management practices endeavor to maintain freshwater flows through a combination of hydraulic and physical barriers and alterations to existing channels (Water Education Foundation, 2019). Portions of the Subbasin do, however, experience water quality issues related to salinity, which are addressed under Section 2.2.4.1 (Salinity). As described in Section

2.2.4.1, salinity in the Subbasin is due to other factors and are not the result of seawater intrusion.

2.2.4 Conditions as of 2019: Groundwater Quality
While groundwater quality in the Eastern San Joaquin Subbasin is generally sufficient to meet beneficial uses, a number of constituents of concern are either currently impacting groundwater use or have the potential to impact it in the future. Depending on the water quality constituent, the source may be anthropogenic in origin or naturally occurring, and the issue may be widespread or localized.

The primary naturally occurring water quality constituents of concern are salinity and arsenic, while the primary water quality constituents related to human activity include nitrates, salinity, and various point-source contaminants.

The sections herein provide information on the historical and current (as of the 2020 GSP) groundwater quality conditions for constituents including:
• Salinity (Section 2.2.4.1)
• Nitrate (Section 2.2.4.2)
• Arsenic (Section 2.2.4.3)
• Point-source contamination (Section 2.2.4.4), which includes petroleum hydrocarbons, solvents, and emerging contaminants
CCR Title 22 establishes water quality standards for drinking water contaminants. A primary maximum contaminant level (MCL) or SMCL is defined for a variety of parameters. For the purposes of this GSP, comparing parameter concentrations to their MCL or SMCL is used as the basis for describing groundwater quality concerns in the Eastern San Joaquin Subbasin. Comparisons to the MCL or SMCL must be considered in context as the measured concentrations represent raw water that may be treated or blended prior to delivery to meet the standard or may not be used for potable uses. Water quality is generally not known to have significantly adversely affected beneficial uses of groundwater in the Eastern San Joaquin Subbasin.

2.2.4.1 Salinity
As identified in prior planning efforts, and as referenced in Section 2.2 (Historical Groundwater Conditions) and Section

2.3 (Current Groundwater Conditions), localized salinity issues are a concern for some areas of the Eastern San Joaquin Subbasin. Pumping in excess of recharge has resulted in declining groundwater levels that have contributed to an increase of salinity in groundwater wells since the 1950s. As identified through isotopic typing, elevated salinity concentrations in the Subbasin are the result of natural processes and overlying land use activities (O’Leary et al., 2015). Within the Subbasin, there are three primary sources of salinity:

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1. Delta Sediments – Evaporation of groundwater in discharge areas introduces naturally occurring soluble salts into Delta sediments.

2. Deep Deposits – Saline groundwater in the Subbasin is principally the result of the migration of a naturally occurring deep saline water body which originates in regionally deposited marine sedimentary rocks that underlie the San Joaquin Valley. This results in a saline aquifer underlying the freshwater aquifer, and well pumping can result in upwelling saline brines into the freshwater aquifer.

3. Irrigation Return Water – Irrigation return water is excess applied water that percolates into the groundwater system or flows to the stream system from an irrigated field following the application of irrigation water. Return water may include contaminants typical of agricultural practices (e.g., pesticides, herbicides) and can concentrate salts due to evapotranspiration. The return water may act as a conduit delivering these contaminants to the surrounding watershed or underlying groundwater aquifer. Areas in the Subbasin with salinity resulting from irrigation return water do not commonly exceed chloride concentrations of 100 mg/L (O’Leary et al., 2015).

Salinity is a measure of the mass of dissolved particles and ions in a volume of water. Salinity includes many different ions, including nitrate, but the most common are sodium, calcium, magnesium, chloride, bicarbonate, and sulfate.

Chloride and TDS are two common ways to measure and analyze salinity. Each is described separately in the sections below.

2.2.4.1.1 Chloride
Chloride is one way to measure salinity and is reported as a concentration of the Clion that originates from the dissociation of salts in water. The California Department of Drinking Water (DDW) SMCL of 250 mg/L for chloride is a common approach to identifying water quality concerns for this constituent. The SMCL is a secondary drinking water standard that is established for aesthetic reasons such as taste, odor, and color and is not based on public health concerns. The 250 mg/L value is “recommended” by SWRCB as a threshold below which chloride concentrations are desirable for a higher degree of consumer acceptance of drinking water. An “upper” limit of 500 mg/L is used to define a range above the “recommended” value where chloride concentration is acceptable if it is neither reasonable nor feasible to provide more suitable waters (SWRCB, 2018). Comparisons to the SMCL must be considered in context as the measured concentrations represent raw water, which may be treated or blended prior to delivery to meet the standard or may not be used for potable uses.

As shown in Figure 2-66, the majority of observed chloride concentrations above 250 mg/L occur on the western side of the Subbasin. As shown in Figure 2-67, the number of measurements with observed concentrations above 250 mg/L has decreased since the 1970s. The GAMA dataset was used for analysis.

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Figure 2-66: Maximum Chloride Concentration Greater Than 250 mg/L (1940s-2010s) EXHIBIT 1
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Figure 2-67: Maximum Chloride Concentration Above 250 mg/L by Decade EXHIBIT 1
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Table 2-5 shows occurrence of chloride measurements greater than 250 mg/L by decade. Chloride records have been observed above 250 mg/L both historically and more recently. Sampling frequencies increased in the 1970s and 2000s.

Table 2-5: Summary of Chloride Data by Decade
Decade Measurement Above
250 mg/L? Range of Values (mg/L) Total Number
of Samples
No Yes Minimum Average Median Maximum
1940 98% 2% 7.0 45.2 20.0 975 180
1950 93% 7% 2.3 89.4 25.0 3,750 699
1960 90% 10% 0.0 115.0 17.0 1,960 312
1970 90% 10% 1.8 85.9 19.0 3,310 1,780
1980 97% 3% 0.0 45.4 20.5 630 858
1990 99% 1% 0.0 31.2 19.0 533 663
2000 95% 5% 0.0 59.6 35.0 2,050 1,453
2010 98% 3% 0.0 34.8 39.0 2,050 986
Table 2-6 shows chloride occurrences of concentrations greater than 250 mg/L by well depth. The highest proportion of readings above 250 mg/L occur in the shallowest wells, less than 100 feet deep (8 percent). The highest maximum value also occurred at this depth range (up to 2,050 mg/L).

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Figure 2-68 shows the spatial distribution of chloride occurrences greater than 250 mg/L by well depth within the Subbasin.

Table 2-6: Summary of Chloride Data by Depth (1940s-2010s) Depth (feet) Measurement Above
250 mg/L? Range of Values (mg/L) Total Number
of Samples
No Yes Minimum Average Median Maximum
No Depth Data 92% 8% 0.0 82.5 20.0 3,750 3,566
0 - 100 92% 8% 0.8 73.5 60.0 2,050 239
100 - 250 97% 3% 1.0 44.2 36.0 1,400 1,215
250 - 500 98% 2% 0.0 32.4 16.0 1,100 1,487
> 500 95% 5% 2.7 62.1 15.6 1,940 424
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Figure 2-68: Maximum Chloride Concentration Above 250 mg/L by Well Depth (1940s-2010s) EXHIBIT 1
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A lack of depth information presents a challenge to analyzing the vertical distribution of chloride measurements which would inform identification of chloride sources. Examples of depth information include total well construction depth or screened interval depths, which vary between wells. Some wells have total depth but not screened interval depth, or vice versa. For this analysis, screened interval depth was used first, and if this information was not available, total depth was used. Approximately 4,600 of the almost 13,000 chloride measurements in the Eastern San Joaquin Subbasin are from wells lacking any construction or screen depth information. Roughly half of the measurements above 250 mg/L occur in the wells lacking depth data, which also show the highest range in values occurring above 250 mg/L.

Identifying the source of high-chloride water in wells of various depths over time requires further analysis of geochemical data.

2.2.4.1.2 Total Dissolved Solids (TDS)
TDS, which is a measure of all inorganic and organic substances present in a liquid in molecular, ionized, or colloidal suspended form, is commonly used to measure salinity. Recent TDS sample results show trends that match closely with the overall historical trends for chloride and highlight areas with elevated salinity concentrations in more recent years. TDS concentrations in the Eastern San Joaquin Subbasin ranged from 35 to 2,500 mg/L between 2015 and 2018. Spatially, the highest concentrations of TDS are found along the western margin of the Subbasin and the San Joaquin River and decrease significantly to the east, to typically less than 500 mg/L. TDS measurements, like chloride levels, are elevated near the cities of Stockton and Manteca, and in the Lodi GSA near the White Slough Water Pollution Control Facility.

Figure 2-69 shows the maximum and Figure 2-70 shows the average TDS concentrations from 2015 to 2018 as compared to the SMCL lower limit of 500 mg/L and upper limit of 1,000 mg/L. The GAMA dataset was used for analysis.

The SMCL is a secondary drinking water standard that is established for aesthetic reasons such as taste, odor, and color and is not based on public health concerns. The 500 mg/L value is “recommended” by the State Water Resources Control Board (SWRCB) as a threshold below which TDS concentrations are desirable for a higher degree of consumer acceptance of drinking water. The “upper” limit is used to define a range above the “recommended” value where TDS concentration is acceptable if it is neither reasonable nor feasible to provide more suitable waters (SWRCB, 2006).

Comparisons to the SMCL must be considered in context as the measured concentrations represent raw water, which may be treated or blended prior to delivery to meet the standard or may not be used for potable uses.

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Figure 2-69: Maximum TDS Concentrations 2015-2018
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Figure 2-70: Average TDS Concentrations 2015-2018
Elevated TDS concentrations are apparent in very shallow groundwater in close proximity to the San Joaquin River, while deep wells (depths greater than 200 feet) typically have TDS concentrations below 500 mg/L. TDS trends by depth are summarized in Table 2-7
Figure 2-71 shows the maximum TDS concentrations for shallow wells in the Eastern San Joaquin Subbasin from years 2015 to 2018, and Figure 2-72 shows the maximum TDS concentrations for deep wells in the same timeframe.

As with chloride measurements, depth-dependent TDS data are not widely available.

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Table 2-7: Summary of TDS Data by Depth (2015-2018)
% Measurements in Range Range of Values (mg/L) Total
Depth (feet) < 500
mg/L
500 – 1000
mg/L
> 1,000
mg/L Minimum Average Median Maximum Number of Samples
No Depth
Data 90% 8% 2% 94 339 310 1,180 451
0 - 100 N/A 0
100 - 250 54% 46% 0% 280 438 480 540 13
250 - 500 93% 7% 0% 120 344 340 560 75
> 500 N/A 0
Figure 2-71: Maximum TDS Concentrations in Shallow Wells 2015-2018 EXHIBIT 1
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Figure 2-72: Maximum TDS Concentrations in Deep Wells 2015-2018 EXHIBIT 1
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2.2.4.2 Nitrate
Nitrate is both naturally occurring and can be contributed a result of human activity. Nitrate can cause adverse human health effects. Anthropogenic sources of nitrate include fertilizers, septic systems, and animal waste. The DDW’s MCL of 10 mg/L for Nitrate as N delimits high levels of nitrate for drinking water use. Many measured concentrations are above this value, both historically and more recently. Comparisons to the MCL must be considered in context as the measured concentrations represent raw water, which may be treated or blended prior to delivery to meet the standard or may not be used for potable uses.

Table 2-8 provides the total number of nitrate values by decade and the percentage of those values greater than 10 mg/L. The total number of nitrate measurements has grown since 2000 as has the percentage of occurrences of concentrations greater than 10 mg/L. The GAMA dataset was used for analysis.

Table 2-8: Nitrate as N Concentrations by Decade
% of Samples
Decade <10 mg/L >10 mg/L Number of Nitrate Samples
1940 88% 13% 8
1950 99% 1% 362
1960 99% 1% 240
1970 96% 4% 1,500
1980 95% 5% 420
1990 98% 2% 1,716
2000 87% 13% 9,679
2010 83% 17% 11,060
Figure 2-73 shows the historical spatial distribution of nitrate samples and detections by decade. During the 1940s, the earliest decade with nitrate measurements, very few records exist, and no significant conclusions can be made from this timeframe. The 1950s and 1960s have larger datasets, but measurements above 10 mg/L during these decades are sporadic and localized. Nitrate concentrations during the 1970s show a significant number of measurements above 10 mg/L in the northwest portion of the Eastern San Joaquin Subbasin, adjacent to Interstate 5. The 1980s and 1990s show similar patterns, with areas measurements above 10 mg/L primarily around the cities of Stockton, Lodi, and Manteca. Nitrate as N measurements above 10 mg/L are also located near the southern edge of the Eastern San Joaquin Subbasin, close to Highway 120. Although a much greater number of records exists for the 1990s than the 1980s, these decades have approximately the same spatial distribution. One possible explanation is similar wells were sampled during the 1980s and 1990s, but much more frequently in the 1990s. The 2000s and 2010s had both the greatest number of nitrate measurements and the largest number of measurements above 10 mg/L. Measurements above 10 mg/L during these decades follow previous trends: they are primarily between Highway 99 and Interstate 5, from Ripon to near Lodi.

Recent (as of 2019) nitrate measurements above the MCL correspond to the overall historical trends and highlight areas with elevated nitrate concentrations in more recent years. These areas include the cities of Stockton and Ripon, areas of the Lodi GSA near the White Slough Pollution Control Facility, the N.A. Chaderjian Youth Correctional Facility, Republic Services Landfill on South Austin Road, and the Kruger and Sons, Inc. site off Highway 4 outside Farmington.

While the extent of groundwater quality impacts from nitrate is a data gap area, increased nitrate concentrations have not been found to have a causal nexus between SGMA-related groundwater management activities in the Subbasin.

The causal nexus reflects that the degraded water quality issues are associated with groundwater pumping and other SGMA-related activities rather than water quality issues resulting from land use practices, naturally occurring water quality issues, or other issues not associated with groundwater pumping. Additional monitoring conducted through the implementation of this GSP will inform trends such that the Eastern San Joaquin Groundwater Authority (ESJGWA) can be informed to take action to address nitrite contamination if a causal nexus is identified.

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Section 3.3 of this Plan discusses Irrigated Lands Regulatory Program (ILRP) and Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS), two existing regulatory programs for the monitoring and regulation of nitrate.

Under the ILRP, the San Joaquin County & Delta Water Quality Coalition is required to test and potentially mitigate for nitrate in domestic wells. Additionally, the 2017 Salt and Nitrate Management Plan developed by CV-SALTS identifies long-term nitrate management practices (CVRWQCB, 2016).

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Figure 2-73: Nitrate as N Concentrations by Decade
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2.2.4.3 Arsenic
Arsenic is ubiquitous in nature and is commonly found in drinking water sources in California. Determining the source of arsenic in groundwater is difficult because arsenic is both naturally occurring and used in human activities such as agriculture. Public health concerns about arsenic in drinking water related to its potential to cause adverse health effects are addressed through DDW’s MCL, established at 10 micrograms per liter (µg/L). California's revised arsenic MCL of 10 μg/L became effective on November 28, 2008. A 10-μg/L federal MCL for arsenic has been in effect since January 2006. Previous California and federal MCLs for arsenic were 50 μg/L.

Figure 2-74 shows the spatial distribution of arsenic concentrations contained in the GAMA database. From the 1970s to present, the total number and percentage of arsenic values above 10 µg/L has increased (see Table 2-9). The spatial distribution of measurements above 10 µg/L is similar to nitrate, largely between Interstate 5 and Highway 99, from Manteca to Lodi. The increased arsenic concentrations near urban areas are not necessarily indicative of contamination from these areas and may partially be due to the fact that arsenic measurements are more abundant in these urban areas; GAMA water quality records are rarely evenly distributed throughout the Subbasin for any constituent. Recent (as of 2019) arsenic samples show measurements above 10 µg/L similar to the overall trends (see Figure 2-75). Measurements above 10 µg/L in years 2015, 2016, 2017, and 2018 are primarily located in the cities of Stockton and Manteca, with fewer occurring around the City of Lodi. While the extent of groundwater quality impacts from arsenic is a data gap area, increased arsenic concentrations have not been found to have a causal nexus between SGMA-related groundwater management activities in the Subbasin.

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Figure 2-74: Arsenic Concentrations by Decade
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Table 2-9: Arsenic Concentrations by Decade
% of Samples
Decade <10 µg/L >10 µg/L Number of Arsenic Samples
1960 100% 0% 1
1970 86% 14% 339
1980 72% 28% 363
1990 72% 28% 645
2000 56% 44% 4,051
2010 48% 52% 5,109
Figure 2-75: Maximum Arsenic Concentrations 2015-2018
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2.2.4.4 Point Sources
Point sources are discrete or discernable sources of pollutants which may introduce undesirable constituents into groundwater and may negatively impact water quality. In the Eastern San Joaquin Subbasin, point sources include leaking underground storage tanks, landfills, dry cleaners, and others. These sites are actively investigated and monitored within the Eastern San Joaquin Subbasin in response to these known or potential sources of groundwater contamination.

The Regional Water Quality Control Board (RWQCB), the Department of Toxic Substances Control (DTSC), and the USEPA provide oversight of point-source pollution through existing regulatory programs, including management of remedial action for point-source contamination sites. Figure 2-76 shows the results of a query from both the GeoTracker database and the EnviroStor database. GeoTracker documents contaminant concerns that the RWQCB is or has been working with site owners to remediate while EnviroStor is the DTSC’s data management system to track known contamination sites undergoing cleanup, permitting, enforcement, and investigation efforts. As shown in Figure 2-76, there are 258 active sites within the Eastern San Joaquin Subbasin which are color-coded based on the site’s constituent(s) of concern: fuels (gas and/or diesel); synthetic organics (pesticides, herbicides, insecticides, etc.); or a mix of constituents (multiple constituents such as heavy metals and pesticides).

Most sites within the Eastern San Joaquin Subbasin are fuel sites (e.g., gas or diesel) that are under active investigation or remediation. Sites with the potential to cause plumes are mapped in Figure 2-77, which were identified by filtering for sites containing soluble and mobile constituents such as volatile organic compounds (VOCs); benzene, toluene, ethylbenzene, and xylenes (BTEX); and/or petroleum hydrocarbons (gas or diesel).

Sites with the potential to cause plumes are currently managed by existing regulatory programs through the RWQCB, DTSC, and USEPA, as described above. New projects undertaken by the GSAs as part of GSP implementation will evaluate contaminant plume movement in a CEQA document. Specific point source sites and contaminants are discussed in the sections below.

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Figure 2-76: Active Investigation and Remediation Sites as of 2019 EXHIBIT 1
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Figure 2-77: Active Sites with the Potential to Cause Plumes

2.2.4.4.1 Publicized Plumes in and near the Subbasin
As indicated above, the Eastern San Joaquin Subbasin has numerous open cleanup sites, including areas contaminated by chlorinated solvents, methyl tertiary-butyl ether (MtBE), pesticides and herbicides, and leaking underground storage tanks. Plume sites are often clustered around urban centers but are also found near sites where historical industrial or agricultural practices have released contaminants of concern. While other plumes exist in and around the Subbasin, three specific plumes have been highly publicized: the Lodi Plumes, the Sharpe Army Depot Plume, and the Occidental Chemical Corporation Plume.

In the late 1980s, the City of Lodi discovered the chlorinated solvents perchloroethylene (PCE) and trichloroethene (TCE) in drinking water supplies and pursued a groundwater investigation that revealed a series of five separate plume areas located in the northeastern portion of the city: the Northern, Western, Central, Southern, and Busy Bee plumes.

The Busy Bee plume, named after a dry cleaner business that previously operated on the site, now has regulatory closure, with cleanup moving toward completion under CVRWQCB oversite (Water Resources Control Board, 2011).

Groundwater contamination plumes in the City of Lathrop, located just outside the Subbasin boundary, include the Sharpe Army Depot and Occidental Chemical Corporation sites. Contamination of groundwater at the Sharpe Army EXHIBIT 1
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Depot consists primarily of trichloroethene, tetrachloroethene, and cis-1,2-dichloroethene from historical industrial activities related to military activities. Due to concerns of potential contamination, the City of Lathrop abandoned their wells in the area. Three groundwater extraction and treatment systems are located at Sharpe Army Dept and are used to treat existing groundwater (EKI Environment & Water, 2015).

The Occidental Chemical Corporation Plume was discovered in the late 1970s and is the result of former leaking wastewater holding ponds containing pesticides and chemicals used for equipment cleaning by the Occidental Chemical Corporation. Contaminants of concern include the pesticides 1,2-dibromo-3-chloropropane (DBCP) and ethylene dibromide (EDB), lindane, 2,3,4,5-tetrahydrothiopene-1, 1-dioxide, sulfate, nitrate, chloride, and BHC (RWQCB, 2012). Since the discovery of these plumes in the 1980s, groundwater monitoring and evaluation at point source locations has led to the implementation of remedial activities such as the installation of groundwater extraction and remedial systems, implementation of a Salinity Reduction Plan, and mandated waste discharge requirements (WDRs) (CVRWQCB, 2012).

2.2.4.4.2 Petroleum Hydrocarbons
Approximately 134 sites in the Eastern San Joaquin Subbasin are identified as actively investigating or remediating an unauthorized release of petroleum hydrocarbons, according to the GeoTracker and EnviroStor databases. At these sites, petroleum hydrocarbon constituents are most commonly fuels (diesel, gasoline, motor oil, or aviation fuel) and VOCs commonly added to fuels, including MTBE and BTEX constituents. Concentrations of petroleum hydrocarbons have not been modeled across the Subbasin; concentrations are local and site specific. A summary description of the aforementioned constituents is provided in Table 2-10 below:

Table 2-10: MCLs for Common Petroleum Hydrocarbons and MTBE Constituent Source Primary MCL
MTBE Oxygenate commonly added to gasoline 13 µg/L
BTEX
Benzene Industrial solvent added to crude oil paint, varnish, and lacquer thinner 1 µg/L
Toluene Aromatic hydrocarbon used in industrial feedstock, as a solvent, and to produce benzene and added to gasoline 150 µg/L
Ethylbenzene Used as a solvent and added to fuel, asphalt, and naphthalene 300 µg/L Xylenes Naturally occurring in petroleum, coal and wood tar 1.750 mg/L Source: (SWRCB, 2018)

2.2.4.4.3 Synthetic Organics
Approximately 47 sites in the Eastern San Joaquin Subbasin are identified as actively investigating or remediating an unauthorized release of synthetic organics, according to the GeoTracker and EnviroStor databases. At these sites, pesticides, herbicides, fertilizer, and pesticides are the most common constituents. Other constituents include VOCs such as PCE and TCE. Concentrations of synthetic organics have not been modeled across the Subbasin; concentrations are local and site specific. For context, a brief description of the aforementioned VOCs is provided in Table 2-11.

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Table 2-11: MCLs for Common Synthetic Organic Constituents Constituent Source Primary MCL1
TCE Used as a solvent in manufacturing facilities and dry cleaners 5 µg/L PCE Used as a solvent in manufacturing facilities, dry cleaners, printing shops, and auto repair facilities 5 µg/L
Note:
1 Source: (SWRCB, 2018)

2.2.4.4.4 Mixed Constituents
Approximately 28 sites in the Eastern San Joaquin Subbasin are identified as actively investigating or remediating an unauthorized release of mixed constituents, according to the GeoTracker and EnviroStor databases. Sites with mixed constituents are those that include a release of more than one type of contaminant, such as a mix of heavy metals, diesel, inorganics, and/or organics. At these sites, the most common constituents include a mixture of heavy metals (chromium, arsenic, and lead), inorganics, and solvents. The sources and primary MCL for many contaminants found in the ‘mixed constituents’ classification have been discussed throughout Section 2.2.4.

2.2.4.4.5 Emerging Contaminants
Many chemical and microbial constituents that have not historically been considered as contaminants are occasionally, and in some cases with increasing frequency, detected in groundwater. These newly recognized (or emerging) contaminants are commonly derived from municipal, agricultural, industrial wastewater, and domestic wastewater sources and pathways. These newly recognized contaminants are dispersed to the environment from domestic, commercial, and industrial uses of common household products and include caffeine, artificial sweeteners, pharmaceuticals, cleaning products, and other personal care products. Residual waste products of genetically modified organisms are also of potential concern. Several studies, such as by Watanabe et al. in 2010, have recently been published or are underway regarding the potential link between dairies and the occurrence of pharmaceuticals in shallow groundwater in the San Joaquin Valley.

Perfluorooctanesulfonic acid (PFOS) and perfluorooctantoic acid (PFOA) are organic chemicals synthesized for water and lipid resistance, used in a wide variety of consumer products as well as fire-retarding foam and various industrial processes. These chemicals tend to accumulate in groundwater, though typically in a localized area in association with a specific facility, such as a factory or airfield (California Water Boards, 2018). There are currently no MCLs for PFOS or PFOA; however, the USEPA is moving forward with establishing the MCL and is recommending municipalities notify customers at levels at or greater than 70 parts per trillion in water supplies (USEPA, 2019). California’s DDW has established notification levels at 6.5 parts per trillion for PFOS and 5.1 parts per trillion for PFOA (SWRCB, 2019). 1,2,3-Trichloropropane (1,2,3-TCP) is a solvent and is typically found in industrial or hazardous waste sites. Along with an industrial solvent, 1,2,3-TCP is a cleaning and degreasing agent and associated with pesticide products. Though there is currently no federal MCL, the MCL for 1,2,3-TCP in California is 0.005 µg/L (SWRCB, 2019).

Currently, data on PFOS, PFOA, and 1,2,3-TCP are limited in the Eastern San Joaquin Subbasin since these are emerging contaminants.

2.2.5 Conditions in 2019: Land Subsidence
Despite long-term declining groundwater levels, there are no historical records of significant and unreasonable impacts from subsidence in the Eastern San Joaquin Subbasin. Figure 2-78 shows regional subsidence produced from TRE Altamira Interferometric Synthetic Aperture Radar (InSAR) data, provided by DWR for SGMA application. InSAR is a satellite-based method for showing ground-surface displacement over time. This figure illustrates that subsidence has historically been minimal in the Subbasin and surrounding areas (ranging from -0.1 to 0.1 feet of vertical displacement annually). The error range of a single InSAR measurement is +/- 5 millimeters (TRE Altamira, 2019). See Section 2.1.5 for a discussion of the soils and clays within the Subbasin, including the extent of Corcoran Clay.

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Figure 2-78: Subsidence (Annual Rate of Vertical Displacement) Note: This dataset represents measurements of vertical ground surface displacement in between spring 2015 and summer 2017 (TRE Altamira, 2019).

2.2.6 Conditions in 2019: Interconnected Surface Water Systems Interconnected surface waters (ISW) are surface water features that are hydraulically connected by a saturated zone to the groundwater system. In these systems, the water table and surface water features intersect at the same elevations and locations. Interconnected surface waters may be either gaining or losing, wherein the surface water feature itself is either gaining water from the aquifer system or losing water to the aquifer system.

In the Eastern San Joaquin Subbasin, stream connectivity was analyzed by comparing monthly groundwater elevations from the historical calibration of the ESJWRM to streambed elevations along the streams represented in ESJWRM.

This analysis was based on modeling results from the historical calibration of the ESJWRM for approximately 900 stream nodes in the Eastern San Joaquin Subbasin, which represents that best available information for current and historical conditions related to interconnected surface water systems. Figure 2-79 shows locations where streams EXHIBIT 1
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are interconnected at least 75 percent of the time (shown in blue) or interconnected less than 25 percent of the time (shown in green).

Disconnected streams will always be losing streams, but interconnected streams may be either losing or gaining, depending on the surface water and groundwater conditions. Groundwater discharge from the aquifer is primarily through groundwater pumping, however, groundwater also discharges to streams where groundwater elevations are higher than the streambed elevations. Figure 2-80 shows mostly gaining streams in blue where groundwater discharges to rivers more than 75 percent of the time, mostly losing streams in red where streams lose water to the groundwater system more than 75 percent of the time, and mixed streams (gaining or losing less than 75 percent of the time) in orange.

Due to limited model calibration based on insufficient calibration information, stream nodes in the Delta area and along stretches of streams near the foothill boundary of the Subbasin are not shown on Figure 2-79 and Figure 2-80.

Interconnected surface water is highlighted as a data gap in Section 4.7.3 due to a lack of data from shallow monitoring wells near streams. Future improvements to the understanding of interconnected surface water include proposed monitoring wells in Section 4.7.5 that are largely located along streams or in areas of the foothills where current monitoring coverage is lacking and a specific project in Section 6.2 to improve understanding of losses along Mokelumne River. Section 7.4.1 discusses model refinements over the next five years in order to improve calibration of the model and its use in analysis of GSP water budgets and sustainability criteria. The analysis in this section includes the results from the 2019 model and Appendix 3-G details an updated analysis.

Figure 2-79 and Figure 2-80 are illustrations to describe model outputs, which are subject to uncertainty and future refinements and are not intended for regulatory purposes beyond the use in this Plan.

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Figure 2-79: Stream Connectivity to the Groundwater System Note: Analysis is based on limited data recognized to have significant gaps. Interconnected surface water is a recognized data gap in the GSP as discussed in Section 4.7.

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Figure 2-80: Losing and Gaining Streams
Note: Analysis is based on limited data recognized to have significant gaps. Interconnected surface water is a recognized data gap in the GSP as discussed in Section 4.7.

2.2.7 Conditions in 2019: Groundwater-Dependent Ecosystems Groundwater-dependent ecosystems (GDEs) are defined in the GSP regulations as “ecological communities or species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface.” SGMA requires the identification of GDEs. SGMA does not require that additional sustainable management criteria be established to specifically manage these areas, but rather includes GDEs as a beneficial user of water to be considered when developing other sustainable management criteria.

GDEs exist where vegetation accesses shallow groundwater for survival. This Plan identifies GDEs within the Eastern San Joaquin Subbasin based on determining the areas where vegetation is dependent on groundwater.

2.2.7.1 Methodology for GDE Identification
The Natural Communities Commonly Associated with Groundwater (NCCAG) database was used as a starting point to identify GDEs within the Subbasin. The NCCAG database was developed by a working group comprised of DWR, California Department of Fish and Wildlife (CDFW), and The Nature Conservancy (TNC). The working group reviewed EXHIBIT 1
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publicly available datasets which mapped California vegetation, wetlands, springs, and seeps and conducted a screening process to retain communities known to be commonly associated with groundwater. The NCCAG database defines two habitat classes: wetland and vegetative. The wetland class includes wetland features commonly associated with the surface expression of groundwater under natural, unmodified conditions. The vegetative class includes vegetation types commonly associated with the shallow subsurface presence of groundwater (phreatophytes). Figure 2-81 shows the location of the two NCCAG classes within the Eastern San Joaquin Subbasin. The distribution of freshwater fish and wildlife species that may be dependent on GDEs is not well known and is not included in this analysis. A list of freshwater species in the Eastern San Joaquin Subbasin is provided in Appendix 1-H. Instream flows for rivers and streams interconnected with groundwater are evaluated through the Depletions of Interconnected Surface Water sustainability indicator (see Section 3.3.6).

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Figure 2-81: Natural Communities Commonly Associated with Groundwater (NCCAGs) Source: NC Dataset Viewer, CADWR Sustainable Groundwater Management (https://gis.water.ca.gov/app/NCDatasetViewer/) EXHIBIT 1
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This Plan uses the NCCAG database as a starting point for identifying potential GDEs. To identify NCCAG areas that are potential GDEs, the analysis identified communities in areas where groundwater levels are shallower than 30 feet bgs, as these areas are thought to be reachable by the root zone of vegetation.1 Oak trees are considered the deepestrooted plant in the region with a root zone of roughly 25 feet.2 This value is considered conservative, as this depth is unlikely to support recruitment of new oak seedlings. NCCAG-identified communities in areas with groundwater shallower than 30 feet were considered as potential GDEs. Communities in areas deeper than 30 feet were identified as data gap areas for future refinement and are labeled on Figure 2-82 as “Depth to Water > 30 ft”. These areas will be refined in future analyses to identify potential existing GDEs that may have been misclassified through this screening process. Additional information regarding plans to fill GDE-related data gaps can be found in Section 4.7.4.

The NCCAG database was then further refined to identify communities without access to alternate water supplies, as those communities would not be dependent on groundwater. This was done by screening for the following: 1) areas not close to managed wetlands, 2) areas not adjacent to irrigated agriculture, and 3) areas not near perennial surface water bodies. NCCAG-identified communities with access to shallow water (less than 30 feet bgs) and without access to alternate water supplies were classified as GDEs. Communities with access to alternate water supplies were identified as data gap areas requiring additional investigation to determine the reliability of the alternate supply. • Proximity to Managed Wetlands – Managed wetlands receive supplemental water to support wildlife habitat.

Managed wetlands, and areas within 150 feet of a managed wetland, are assumed to be able to access this supplemental delivered water regardless of the condition of the underlying aquifer. Areas farther than 150 feet from a managed wetland that meet the other GDE criteria in this section are assumed to be dependent on groundwater and were identified as GDEs. A criterion of 150 feet was used to reflect ponded conditions at the wetlands. Identified wetlands were reviewed with local water managers to verify supplemental water deliveries.

NCCAG-identified communities not identified as GDEs through this analysis are identified as data gap areas for future refinement and are labeled on Figure 2-82 as “Managed Wetland”. These areas will be refined in future analyses to determine if the alternate source of surface water is reliable over time and to identify potential existing GDEs that may have been misclassified through this screening process. • Adjacent to Irrigated Agriculture – Irrigated agricultural lands are dependent on regular irrigation. This irrigation benefits not only the crops, but also the surrounding vegetation. Irrigated lands, and areas within 50 feet of irrigated lands, are assumed to be able to access this supplemental delivered water regardless of the condition of the underlying aquifer. Areas farther than 50 feet from irrigated lands that meet the other GDE criteria in this section are assumed to be dependent on groundwater and were identified as GDEs. A criterion of 50 feet was used to reflect non-ponded conditions in the fields.

NCCAG-identified communities not identified as GDEs through this analysis are identified as data gap areas for future refinement and are labeled on Figure 2-82 as “Adjacent to Agriculture”. These areas will be refined in future analyses to determine if the alternate source of surface water is reliable over time and to identify potential existing GDEs that may have been misclassified through this screening process. • Proximity to Perennial Surface Water Bodies – Perennial surface water bodies provide year-round water supplies that can be accessed by adjacent vegetation. These water bodies include much of the Delta; large, managed rivers; and smaller water bodies that flow throughout the summer due to agricultural deliveries or 1 This analysis uses 2015 groundwater levels (winter, spring, summer, and fall), which may be deeper than representative levels due to drought conditions, a factor which will be considered in future GDEs analyses. 2 Quercus chrysolepis (canyon live oak) has a maximum rooting depth of 7.3 meters (23.95 feet) (Canadell et al., 1996).

Quercus lobata (valley oak) has a maximum rooting depth of 7.41 meters (24.31 feet), although available data are from fractured rock aquifers (Lewis & Burgy 1964 and Schenk, H. J. and Jackson, R. B. 2002, as cited in TNC, 2019).

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tailwater. Areas within 150 feet of such surface water bodies are assumed to be able to access that surface water regardless of the condition of the underlying aquifer. Areas father than 150 feet from such surface water bodies that meet the other GDE criteria in this section are assumed to be dependent on groundwater and were identified as GDEs. A criterion of 150 feet was used to reflect open water conditions in the surface water bodies.

NCCAG-identified communities not identified as GDEs through this analysis are identified as data gap areas for future refinement and are labeled on Figure 2-82 as “Perennial Surface Water Bodies”. These areas will be refined in future analyses to determine if the alternate source of surface water is reliable over time and to identify potential existing GDEs that may have been misclassified through this screening process.

Next, areas identified as GDEs were ground-truthed electronically with GSA staff and Groundwater Sustainability Workgroup (Workgroup) members. Through this process, areas identified GDEs were investigated, and areas identified as known irrigated parcels such as parks were reclassified. These areas are labels on Figure 2-82 as “Stakeholder Comment.”
This methodology was developed to focus groundwater management activities on the most appropriate areas. The distinction between GDEs and other wetland or vegetative areas is important from a management perspective, as GDEs are expected to be more responsive to changes in groundwater management. Management of communities that access alternate supplies, on the other hand, may require greater focus on land use protection or irrigation activities, for which the GSAs have limited authority to manage through SGMA.

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Figure 2-82: NCCAGs Identified as Data Gap Areas for Future Refinement, Likely to Access Non-groundwater Water Supplies EXHIBIT 1
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2.2.7.2 Areas Identified as GDEs
Following the methodology presented above, this Plan identifies several GDEs, primarily located along the western boundary of the Subbasin and in the Delta areas where groundwater is typically shallow. These areas are divided into two categories: Vegetative GDEs and Wetland GDEs, as shown in Figure 2-83.

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Figure 2-83: Areas Identified as GDEs
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2.3 CURRENT GROUNDWATER CONDITIONS
This section describes the current groundwater conditions in the Eastern San Joaquin Subbasin since development of the 2020 GSP.

As required by the GSP regulations, the current groundwater conditions section includes:
• Definition of current groundwater conditions in the Subbasin • Description of the distribution, availability (storage), and quality of groundwater • Identification of interactions between groundwater, surface water, groundwater dependent ecosystems, and subsidence
Current conditions are generally assumed to be the conditions of the Subbasin roughly between WY 2020 and WY 2023, unless otherwise noted in the below sections.

2.3.1 Groundwater Elevation

2.3.1.1 Groundwater Levels
For the purposes of the 2024 GSP, the most current groundwater elevation conditions were characterized as fourth quarter 2022 (recent seasonal low, measured in fall 2022) and first quarter 2023 (recent seasonal high, measured in spring 2023) groundwater elevation measurements. However, WY 2023 represented a wetter than average water year.

For comparison, fourth quarter 2019 and first quarter 2020 of WY 2020 are also included. WY 2020 was a dry year.

Groundwater elevations were mapped using wells with available data in WDL.

Figure 2-84 and Figure 2-85 show the groundwater elevations for WY 2020. Figure 2-86 and Figure 2-87 show the groundwater elevations for WY 2023. A pumping depression at the center of the Subbasin, east of the City of Stockton, generally exists during periods of lower groundwater elevations, as shown in Fourth Quarter 2019, First Quarter 2020, and Fourth Quarter 2022. In wetter years, this pumping depression can recover, as shown in First Quarter 2023. Similar to historical conditions, groundwater generally flows from the outer edges of the Subbasin towards the depression in the middle of the Subbasin. The predominant hydraulic gradient across the Subbasin is from east to west.

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Figure 2-84: Fourth Quarter 2019 Groundwater Elevation (WY 2020) EXHIBIT 1
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Figure 2-85: First Quarter 2020 Groundwater Levels (WY 2020) EXHIBIT 1
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Figure 2-86: Fourth Quarter 2022 Groundwater Elevation (WY 2023) EXHIBIT 1
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Figure 2-87: First Quarter 2023 Groundwater Levels (WY 2023) Hydrographs are reported annually to DWR in the Annual Reports for 76 single completion wells and 52 nested wells.

The most recent hydrographs for these wells can be found in the WY 2023 ESJ Subbasin Annual Report, available on DWR’s SGMA Portal (https://sgma.water.ca.gov/portal/). All hydrographs show yearly cycles of groundwater level declines in summer due to typical patterns in groundwater pumping and recharge during winter recovery.

2.3.1.2 Reported Dry Wells
According to DWR’s Dry Well Reporting System, San Joaquin County has had 106 reported dry wells since the start of WY 2020 (CA Department of Water Resources, 2023). Figure 2-88 shows the number of reports made to DWR by month between WY 2020 and WY 2023. However, it is important to note that dry wells are reported for many reasons other than a failure due to increasing depth to groundwater. Staff interviews with DWR confirmed that the system does not determine the cause of the well failure unless monitored by outside parties. As expected, reports of dry wells were higher in the critical years of WY 2021 and 2022 than in WY 2023, a wet year.

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Figure 2-88 : Number of Reported Dry Wells in San Joaquin County between WY 2020-2023

2.3.2 Groundwater Storage
The ESJWRM was used to estimate historical change in storage of the Eastern San Joaquin Subbasin from 1995-2023.

Figure 2-89 shows the cumulative change in storage against annual storage change and water year type, including current condition years WY 2020 through 2023. The cumulative change in storage from 1996 to 2023 was estimated as on average -0.34 million acre-feet per year (MAF/year). More information about the layers of the ESJWRM and calculation of storage changes can be found in model documentation in Appendix 2-C.

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Figure 2-89: Modeled Change in Annual Storage with Water Use and Year Type Notes:

4. Water Year Types based on San Joaquin Valley Water Year Index (CA DWR, 2024)

5. “Other Recharge” includes managed aquifer recharge, recharge from unlined canals and/or reservoirs, and recharge from ungauged watersheds.

6. “Change in Storage” is placed to balance the water budget. For instance, if annual outflows (-) are greater than inflows (+), there is a decrease in storage, but this would be shown on the positive side of the bar chart to balance out the increased outflows on the negative side of the bar chart.

2.3.3 Seawater Intrusion
The northwest corner of the Eastern San Joaquin (ESJ) Subbasin overlies a portion of the Delta. The Delta originally experienced groundwater fluctuations closely tied to tidal cycles, with a mix of brackish, saline ocean water, and fresh streamflow typical of an inland river delta and estuary. However, after decades of land reclamation and the implementation of managed operations as a result of the State Water Project and Central Valley Project, the Delta is now managed as a freshwater body. Saline water is no longer able to migrate eastward beyond the extensive network of levees and engineering alterations to the original natural channels. As a result, seawater intrusion has not historically been observed within the Subbasin nor is it likely to occur in the future.

The following section provides analysis supporting this claim, demonstrating that:

1. The Delta is managed as a freshwater body in the Subbasin

2. There is minimal pumping near the Delta

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Further detail can be found in Appendix 3-F.

2.3.3.1 Delta is Managed to Maintain Freshwater Flows
The Subbasin is located in the Delta region. Prior to the construction of the Shasta Dam in 1943, brackish water had entered the surface waterways throughout the Delta. The Delta ecosystem naturally adapted to a salinity cycle that brought brackish tidal water from the San Francisco Bay. However, the construction of levees for agricultural development, followed by the development and operation of the Central Valley Project and the State Water Project, has changed the pattern of seawater movement into the Delta (Water Education Foundation, 2019). Historically, some saltwater may have infiltrated the aquifers locally affecting groundwater quality. Current management practices aim to maintain freshwater flows in the Delta through a combination of hydraulic and physical barriers and modifications to existing channels (Water Education Foundation, 2019). The ”X2” barrier, where the salinity is approximately 2 parts per thousand (ppt), is located well outside of the Subbasin boundary further downstream in the Delta (Cloern, 2012). (For reference purposes, the salinity of the ocean is about 35 ppt.) Various agencies and regulations, such as the Delta Protection Commission (DPC), Delta Stewardship Council, San Joaquin County & Delta Water Quality Coalition, and State Water Board Resolution No. 2009-011, contribute to managing and maintaining salinity conditions in the Delta region.

2.3.3.2 Minimal Groundwater Pumping Near the Delta
Figure 2-90 presents the Subbasin’s 2023 average groundwater pumping in feet across the Subbasin. The majority of pumping is in the northwest portion of Subbasin, areas adjacent to the Delta pump less than half a foot of groundwater per year.

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Figure 2-90: 2023 Annual Groundwater Pumping
This figure reflects groundwater pumping from the 2023 Eastern San Joaquin Annual Report. Results may vary with the updated 2024 Eastern San Joaquin Water Resources Model.

2.3.3.3 Low Chloride Concentrations
Historical and current chloride concentrations were analyzed in the Subbasin. A variety of groundwater quality data were collected and examined. The datasets used for this analysis include (1) the Groundwater Ambient Monitoring and Assessment (GAMA) database, (2) The National Water (NWQMC) database, (3) the region’s Opti Data Management System (DMS), and (4) SGMA Data Viewer (DWR). From these datasets, 4,000 unique wells were utilized with approximately 19,500 chloride observations.

Most wells had chloride concentrations well below the SMCL of 250 mg/L for chloride. (Secondary MCLs are established as guidelines to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor. Contaminants with SMCLs are not considered to present a risk to human health and are not enforced.) Chloride concentrations throughout the Subbasin have remained relatively low. Table 2-12 shows the percentage of chloride measurements after 2015 that exceed thresholds of 250 mg/L, 500 mg/L, and 2,000 mg/L.

Notably, the majority of measurements (80%) fell within the 0–250 mg/L range, indicating low chloride levels throughout the Subbasin. Additionally, 14% of chloride observations were in the 250–500 mg/L range. Overall, 94% of measurements are below the 500 mg/L threshold. This analysis demonstrates that chloride concentrations in the Subbasin are generally low.

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Table 2-12: Chloride Concentrations after 2015
Threshold Concentration Percentage of Measurements after 2015 above Threshold
250 mg/L 14%
500 mg/L 5%
2,000 mg/L 1%
Chloride measurements in Table 2 are based on approximately 19,500 observations from 4,000 unique wells.

Figure 2-91 shows the average chloride concentration in the Subbasin since January 2015. These results are consistent with the ranges shown in Table 2-12. As shown in Figure 2-91, the majority of chloride concentrations in the Subbasin are within the 0 to 250 mg/L range. There are instances of higher concentrations in the 250 to 500 mg/L range, localized within the central and western regions of the Subbasin. Notably, these areas of relatively higher chloride concentrations are not located only in the Delta area and do not form a seawater intrusion front pattern. Overall, concentrations of chloride in the Subbasin are minimal and seawater intrusion is not occurring in the Subbasin or expected to occur in the future.

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Figure 2-91: Average Chloride Concentrations Post-2015

2.3.4 Groundwater Quality
In addition to the chloride data shown in Section 2.3.3, available recent TDS data from the Groundwater Ambient Monitoring and Assessment (GAMA) Program were also analyzed to characterize current groundwater quality conditions. The locations, observations, and concentrations of the new set of monitoring wells were examined, as shown in Figure 2-92 through Figure 2-94.

Figure 2-92 illustrates the count of TDS groundwater quality observations for each well between January 2015 and January 2024. The majority of wells have 10 or fewer observations, indicating that most wells were not sampled on an annual basis. Several wells closer to the City of Stockton have up to 50 groundwater quality observations. The wells with the highest sample count appear to be located near groundwater cleanup sites. Ideally, wells in the representative monitoring network for groundwater quality would have been sampled regularly; however, some wells in the specific areas have not sampled frequently (greater than 10 times) in recent years.

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Figure 2-93 displays wells with TDS observations in recent years (2015 through early 2024) by well depth. The threshold between shallow and deep wells was set at 200 feet for consistency with the 2020 GSP. There were several wells without perforation or depth information. Between shallow, deep, and unknown well depths, there is a similar distribution of high- and low-quality groundwater. In other words, TDS was not observed in just the shallow portions or just the deep portions of the aquifer.

Figure 2-94 illustrates the maximum TDS concentrations since January 2015. The majority of wells have TDS concentrations below 600 mg/L (the measurable objective for TDS). However, some wells have recent TDS concentrations above 1,000 mg/L (the minimum threshold for TDS). These wells are primarily located near the City of Stockton. Public water purveyors closely monitor groundwater quality and source and treat their water accordingly.

Figure 2-92: Monitoring Frequency for Wells Measuring Total Dissolved Solids EXHIBIT 1
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Figure 2-93: Wells with Recent TDS Observations by Well Depth EXHIBIT 1
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Figure 2-94: Maximum Concentrations for Wells Measuring Total Dissolved Solids

2.3.5 Land Subsidence
SGMA requires monitoring and reporting on inelastic land subsidence. In the Subbasin, subsidence concerns, if any, are focused on the non-Delta area as the Delta region contains peaty soils. Peaty soils can subside due to peaty soil oxidation. Peat oxidation occurs when the peaty soils dewater and come into contact with air, causing the soils to break down and compress, and is not a mechanism caused by groundwater overdraft.

Within the Eastern San Joaquin Subbasin, there are three primary sources of subsidence data, each with different periods of record and methods of data collection:
• CGPS vertical displacement data from the DWR SGMA Data Viewer • InSAR subsidence rates from the SGMA Data Viewer
• Survey benchmarks from U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), California Department of Transportation (CalTrans), the San Joaquin County Department of Public Works, and local agencies.

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There are no DWR or USGS extensometers in the Eastern San Joaquin Subbasin. The datasets used are detailed further below.

2.3.5.1 CGPS Data
Vertical displacement data from CGPS stations are available for download from the DWR SGMA Data Viewer (DWR, 2024). Two CGPS stations are monitored by UNAVCO and two by Scripps Orbit and Permanent Array Center (SOPAC). Of the SOPAC stations, Station P309, is the northeast region of the Subbasin north of the Calaveras River and has a period of record from March 4, 2006, to January 19, 2024. Station P273, in the northwest region of the Subbasin, has data from November 10, 2005, to December 28, 2020. P273 lies in the Delta region of the Subbasin.

The two UNAVCO CGPS stations are CNDR and MTWK. CNDR, in the western region of the Subbasin, has data from April 30, 1999, to February 14, 2006, but is no longer monitored. MTWK, in the southern region of the Subbasin south of the city of Manteca, has data from December 12, 2019, to January 19, 2024. This is the closest CGPS station to the location of the Corcoran Clay. Clay-rich zones are prioritized for monitoring since groundwater over-extraction in these areas can lead to dewatering and compression of the clay aquitards, and inelastic land subsidence.

Several additional CGPS stations from the University of Nevada Geodetic Laboratory (UNGL) are also monitored for subsidence (UNGL, 2024). Station CA15 is located north of the city of Stockton and has a continuous period of record between September 2013 and October 2021. Station CMNC is located along the southern edge of the Camanche Reservoir and has observations in 2020 and between February 2022 through January 2024. These locations also provided additional spatial coverage to the UNAVCO and SOPAC CGPS stations.

Figure 2-95 through Figure 2-98 show time series graphs of subsidence for the four CGPS stations in this analysis.

Between 2015 and 2023, all of the CGPS stations showed that less than one foot of subsidence was observed throughout the Subbasin. The accuracy of GPS data is estimated to be ± 2 inches (CA DWR, 2017).

Figure 2-95 shows a time series graph of subsidence for CGPS Station MTWK. The graph indicates a slight downward trend, reflecting a small increase in subsidence in the Subbasin. From January 2023 to July 2023, subsidence increased slightly more, though overall subsidence remains minimal. The trend line's slope of -0.0295 inches per month (or -0.354 inches per year) confirms that subsidence is occurring in the Subbasin, but at insignificant levels.

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Figure 2-95: CGPS Station MTWK – Subsidence Time Series Figure 2-96 shows a time series graph of subsidence for CGPS Station P309. The graph indicates a very slight downward trend, reflecting a small increase in subsidence in the Subbasin. However, the displacement data varies to a great degree, increasing and decreasing throughout 2006 to current conditions. From June 2015 to June 2016, subsidence increased slightly more, with an overall subsidence of approximately 0.7 inches. This data point represents the largest observed subsidence across the four CGPS stations but still shows no inelastic subsidence. The trend line's slope of -0.0004 inches per month (-0.005 inches per year) confirms that subsidence occurring in this region is elastic and negligible.
y = -0.0295x + 0.1815
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1.2 2019-112020-052020-072020-092020-112021-012021-032021-052021-072021-092021-112022-012022-032022-052022-072022-092022-112023-012023-032023-052023-072023-092023-112024-01 Vertical Displacement (in)
CGPS Station MTWK
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Figure 2-96: CGPS Station P309 – Subsidence Time Series Figure 2-97 shows a time series graph of subsidence for CGPS Station CMNC, located in the northeastern region of the Subbasin, along the southern edge of the Camanche Reservoir. Overall, there is a very slight rise in ground elevation that could be due to several factors, such as swelling of clay soils in wet winters. There is no inelastic subsidence occurring at this CGPS station. As previously mentioned, CPGS Station CMNC is being monitored by UNGL and its data are subject to data gaps and discontinuous monitoring due to its academic nature. While the dataset does not have a long period of record, it supports the observation that subsidence has not historically been an issue in the Subbasin.
y = -0.0004x + 0.2946
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Figure 2-97: CGPS Station CMNC – Subsidence Time Series Figure 2-98 shows a time series graph of subsidence for CGPS Station CA1S, located in the western region of the Subbasin, north of the City of Stockton. The graph indicates a downward trend, reflecting a small increase in subsidence in the Subbasin. The subsidence observed for CGPS Station CA1S shows that subsidence was generally increasing in the Subbasin, and this is reflected in the slope of the trendline. The trend line's slope of -0.0286 inches per month (-0.34 inches per year) shows that the rate of subsidence at this region of the Subbasin is relatively greater than that of the other three CGPS stations but is still relatively minimal as compared to the overall accuracy of the data.

The largest observed vertical displacement in this period of record was -0.261 inches, from December 2022 to January 2023, which is a small degree of subsidence. Important to note that, like CGPS Station CMNC, this dataset is obtained by UNGL and subject to data gaps and discontinuous monitoring. y = 7E-07x - 0.0275
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CGPS Station CMNC
Ave Displacement (inches)
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Figure 2-98: CGPS Station CA1S – Subsidence Time Series

2.3.5.2 InSAR
InSAR data were collected from the SGMA Data Viewer sourced from the California Natural Resources Agency (CNRA). Included in this dataset are point data that represent average vertical displacement values for raster data for total and annual vertical displacement rates in monthly time steps. The longest period of record, at the time of analysis, was from June 13, 2015, to October 1, 2023.

The subsidence analysis using InSAR data revealed minimal subsidence rates across the Subbasin. The highest observed subsidence rate was in the central region, averaging 0.92 inches per year between 2015 and 2023. In contrast, subsidence is not occurring in the eastern region of the Subbasin; instead, the ground elevation has increased due to the swelling of clayey soil in the foothills. This observation is supported by the subsidence analysis for CGPS Station CMNC in the eastern Subbasin which showed positive vertical displacement, indicating a rise in ground elevation. The western region of the Subbasin, adjacent to the Delta, is likely experiencing land subsidence due to peat oxidation rather than groundwater extraction. Figure 2-99 illustrates that the central portion of the Subbasin in the cone of depression area is more prone to land subsidence. Despite this, overall subsidence in the Subbasin remains minimal and is not expected to cause undesirable effects.
y = -0.0286x + 0.2332
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CGPS Station CA1S
Ave Displacement (in) Linear (Ave Displacement (in))
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Figure 2-99: Subsidence Rates (inches per year) Throughout the Subbasin Note: InSAR period of the record displayed in the figure above is June 13, 2015, to October 1, 2023 While CGPS data are more accurate than InSAR vertical displacement measurements, InSAR can estimate subsidence rates over a large land area. Compared to CGPS stations, InSAR has a 16 mm vertical accuracy at a 95% confidence level and an estimated 12 mm (0.47 inches) accuracy near Eastern San Joaquin (Towill, 2020).

2.3.5.3 Survey Benchmarks
Survey benchmark data were collected from USGS, ACOE, CalTrans, the San Joaquin County Department of Public Works (DPW), and local agencies. While there is a high density of benchmarks in the Subbasin, they are not surveyed regularly.

In March 2024, Stockton East Water District (SEWD) conducted benchmark surveys for subsidence monitoring. The aim was to verify claims by the DWR that approximately 7 inches of subsidence had occurred in the area over the past seven years. SEWD surveyed the current elevations of six National Geodetic Survey (NGS) benchmarks with published elevations to compare the historical data with current measurements. These benchmarks, all established in 1962, are located along Comstock Road. The survey results indicated that the average subsidence from the published elevations (1962) to current conditions (March 2024) is approximately 9.3 inches, with a range of subsidence spanning 12.72 EXHIBIT 1
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inches. The greatest subsidence observed was at NGS Survey Benchmark H-956, which showed a subsidence of

16.56 inches over the 62-year period, or 0.27 inches per year. Due to the temporal differences in subsidence observations, this 62-year period does not provide a precise measurement to directly compare with DWR's InSAR 8- year subsidence data from 2015 to 2023 with an average subsidence rate of 0.92 inches per year.

It is also noteworthy that the six surveyed benchmarks are all located in the central region of the Subbasin, where InSAR data indicated the highest subsidence rate of 0.92 inches per year. While the subsidence of 16.56 inches at NGS Survey Benchmark H-956 is significant, it must be considered within the context of the 62-year period. The benchmark survey results suggest that subsidence in the Subbasin is not occurring at significant levels and is not expected to cause undesirable effects.

2.3.5.4 Relationship with Groundwater Levels
Historically, the Subbasin has not had significant or undesirable effects caused by inelastic land subsidence. Examining recent CGPS vertical displacement data, less than one foot of subsidence was observed throughout the Subbasin between 2015 and 2023. While the 2020 GSP originally considered groundwater levels as a proxy for subsidence, a strong correlation was not observed.

Figure 2-100 shows a time series graph of subsidence (vertical displacement of land surface) and groundwater elevation for CGPS Station MTWK, with Manteca 18 as the respective groundwater level RMW. The graph indicates a slight downward trend in land surface elevation, reflecting a small increase in subsidence rates in the Subbasin. From January 2023 to July 2023, land surface elevations increased slightly more when groundwater levels declined, though overall subsidence remains minimal. It is important to note that, while there was a significant drop in groundwater elevations during September 2023, when groundwater levels recovered in the winter of 2024, subsidence reversed.

This shows elastic subsidence that can recover with sustainable groundwater levels. Note that the historical groundwater levels in this example did not decline below MT for that RMW.

Figure 2-100: CGPS Station MTWK: Subsidence Time Series Figure 2-101 shows a time series graph of subsidence (vertical displacement of land surface) and groundwater elevations for CGPS Station CNDR, with Woodbridge 03N06E05N003 as the respective RMW. The graph indicates a slight downward trend in land surface elevations, reflecting a small increase in subsidence in the Subbasin. The trend line's slope of -0.0105 inches per month confirms that subsidence is occurring in the Subbasin, but at very low levels.

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at this location; however, it is important to note that while there was a sharp decline in groundwater elevation during October 2000, subsidence appears to be unaffected. The Woodbridge 03N06E05N003 groundwater level representative monitoring well was selected for analysis because it is the only representative monitoring well that has historically declined below its respective minimum threshold. CNDR CGPS station was selected because it is the only CGPS station with historical observations during the period when the groundwater levels were below minimum thresholds.

Figure 2-101: CGPS Station CNDR – Time Series of Subsidence and Groundwater Levels

2.3.6 Interconnected Surface Water Systems

2.3.6.1 Definitions
Section 2.2.6 detailed the original depletions analysis in the 2020 GSP. This section provides an update to that analysis based on guidance provided by DWR and updates to ESJWRM to reflect current conditions as of the development of this 2024 Amended GSP. More detail can be found in Attachment 3-F, including an extensive update to the historical ISW conditions analysis. As described in Depletions of ISW: An Introduction (CA DWR, 2024), the first of three guidance documents on ISWs released by DWR, the consideration and interpretation of ISWs can be based on five example cases of nearby groundwater elevation data (Figure 5 of Depletions of ISW: An Introduction). Of the examples provided, Figure 5d is most applicable to Eastern San Joaquin Subbasin due to a lack of shallow monitoring wells and associated historic data near the rivers and creeks in the Subbasin (shown in the DWR guidance document and Appendix 3-G). This lack of shallow groundwater level data near surface water courses translates to a low degree of confidence in model calibration around these surface water features and therefore uncertainty around what is or is not a connected reach or model node.

GSP regulations require the identification of ISWs within a basin (and therefore identification of the degree of connectivity) and an estimate of the timing and quantity of depletions of those systems, where depletions are defined as “conditions where groundwater pumping results in reductions in flow or water levels of ISW.” However, the DWR guidance document notes that “the definition above differs from how depletions may be defined in other hydrologic contexts, where they can refer to any surface water losses without considering the cause.” A good faith effort was conducted to isolate stream depletions in the ESJ Subbasin due solely to groundwater pumping by comparing (1) pumping and no-pumping scenarios and (2) a pumping “pulse” scenario to examine the delayed impact of pumping on stream depletions, both using the integrated Eastern San Joaquin Water Resources Model Version 3.0 (ESJWRM).

However, the analyses resulted in an inconclusive understanding of depletions due to pumping since an equilibrium was not reached within the simulation period and depletions were heavily influenced by initial and boundary conditions.

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of cause. This allows the GSAs to have more confidence in the results and be able to manage and report depletions in future Annual Reports without limitations and uncertainties from the existing toolset. At the time of the 2024 GSP, the additional guidance documents from DWR (Techniques for Estimating Depletions of Interconnected Surface Water and Examples of Approaches for Estimating Depletions of Interconnected Surface Water) had not yet been released.

The timing, location, and volume of depletions in the ESJ Subbasin will be revised at a later time in coordination with further guidance from DWR.

2.3.6.2 Stream Connectivity
Stream connectivity was analyzed by comparing monthly groundwater elevations from the historical calibration of the ESJWRM to streambed elevations along the streams represented in ESJWRM. The reaches in ESJWRM are displayed in Figure 2-102. Layer 1 groundwater levels were used since the new Layer 1 in ESJWRM represents the shallow, generally unconsolidated sediments where stream interaction is happening. Stream connectivity was also analyzed under current conditions, represented by Water Year 2020 through 2024 in the historical ESJWRM model. “75% Connected” streams were defined as Layer 1 groundwater levels at or above the streambed elevation at least 75 percent of the time. The definition of ISWs is not limited to surface waters that the ESJGWM indicates are connected to the shallowest modeled groundwater level at least 75 percent of the time. The GSAs understand that an ISW may be seasonally connected and/or connected in only wetter water year types. The GSAs currently do not have sufficient data to determine if or when streams or reaches are connected to the groundwater table with this level of granularity. The GSAs will be collecting more data with the new ISW monitoring wells to help inform this analysis going forward. Using ESJWRM Version 3.0, which was the best available tool at the time of analysis, EXHIBIT 1
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Figure 2-103 shows that the 75 percent connected streams are the Mokelumne River, Stanislaus River, and lower San Joaquin River. Streams that are not connected at least 75 percent of the time are Dry Creek, Calaveras River, and Mormon Slough. Other smaller creeks are not represented in ESJWRM.

Figure 2-102: Stream Reaches in ESJWRM
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Figure 2-103: Surface Waters Connected with the Groundwater System at least 75% of All Months in ESJWRM under Current Conditions
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2.3.6.3 Stream Gains and Losses
Disconnected streams will always be losing streams, but interconnected streams may be either losing or gaining, depending on the surface water and groundwater conditions. Groundwater discharge from the aquifer is primarily through groundwater pumping; however, groundwater also discharges to streams where groundwater elevations are higher than the streambed elevations and stream levels or stage. Figure 2-104, from DWR’s Depletions of ISW: An Introduction (CA DWR, 2024), illustrates connected gaining streams (on the left) where groundwater levels are higher than the stream stage, and losing streams (on the right) where groundwater levels are lower than the stream stage.

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Figure 2-105 shows the average annual volume of stream gains under current conditions (Water Year 2020 through 2023). While the Mokelumne River is a connected river in most years, it is losing water from the stream to the aquifer system upstream of the Cosumnes River, and gaining water from the aquifer system downstream of the Cosumnes River, on average. The Stanislaus River has a high number of stream nodes in the center portion of the river that are losing under current conditions. The lower San Joaquin River is gaining in many sections near the confluence with the Stanislaus River, Calaveras River, and in the Delta region.

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Figure 2-105: Current Conditions Average Annual Stream Gains by Stream Node

2.3.7 Groundwater-Dependent Ecosystems
In the Eastern San Joaquin Subbasin, the primary environmental beneficial users are groundwater dependent ecosystems. In the 2020 GSP, potential GDEs were mapped across the Subbasin. The mapping relied on the Natural Communities Commonly Associated with Groundwater (NCCAG) database, from which additional refinements were made to remove areas that met the following criteria:
• Areas where groundwater levels were deeper than 30 feet below the ground surface (ft bgs). • Areas with access to alternate water supplies that may not be dependent on groundwater (i.e., communities close to managed wetlands, irrigated agriculture, or perennial surface water bodies).

The resulting desktop mapping was then considered by GSA staff and technical workgroup members before inclusion in the GSP. Further detail on this approach to mapping potential GDEs is described in Appendix 3-C of this GSP Amendment.

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Before conducting the analysis to evaluate the potential impacts of the groundwater level SMC on potential GDEs, it was verified that no changes to the NCCAG dataset within the ESJ Subbasin have been made since 2020. The NCCAG database still represents the most comprehensive source of potential GDEs within this Subbasin. Polygons in the NCCAG dataset were removed where the vegetative community’s average maximum rooting depths do not intersect with groundwater. In other words, if the vegetation is not able to access groundwater within its rooting depth, then it is assumed that the ecosystem is not a potential GDE. This average maximum rooting depth is estimated to be 30 feet below ground surface for the majority of phreatophytes (The Nature Conservancy, 2021). The original mapping completed as part of the 2020 GSP was retained in this GSP Amendment.

The map of potential GDEs included in the 2020 GSP is shown in Figure 2-106. This mapping of potential GDEs represents a desktop analysis that will continue to be improved through field verification.

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Figure 2-106: Mapping of Potential Groundwater Dependent Ecosystems

2.4 WATER BUDGETS

2.4.1 Water Budget Background Information
Water budgets are developed to provide a quantitative account of water entering and leaving the Eastern San Joaquin Subbasin. Water entering and leaving the Subbasin includes flows at the surface and in the subsurface environment.

Water enters and leaves due to natural conditions, such as precipitation and streamflow, and/or through human activities, such as groundwater pumping or recharge from applied water. Additionally, interconnection between the groundwater system and rivers/streams accounts for other components of the water budget. Figure 2-107 depicts the major components of a water budget and their interconnection as presented in the context of stream, land surface, and groundwater systems.

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Figure 2-107: Generalized Water Budget Diagram
Quantities presented for the water budget components of the Eastern San Joaquin Subbasin provide information on historical, current, and projected conditions as they relate to hydrology, water demand, water supply, land use, population, climate variability, groundwater and surface water interaction, and groundwater flow. This information can assist in the management of the Subbasin by identifying the relationship between different components affecting the water budget of the Subbasin, which provides context in the development and implementation of strategies and policies to achieve Subbasin groundwater sustainability conditions. Water budget quantities presented are based on the simulation results from the ESJWRM.

The ESJWRM was developed to be the primary analysis tool supporting the development of the GSP for the Subbasin.

The ESJWRM is a quasi-three-dimensional finite element model developed using the Integrated Water Flow Model (IWFM) simulation code (Dogrul et al., 2024a and Dogrul et al,. 2024b). Using data from federal, state, and local resources, the ESJWRM was originally calibrated for the 20-year hydrologic period of October 1995 to September 2015 (water years 1996 through 2015) for the 2020 GSP by comparing simulated groundwater levels and streamflow records with historical observed records. Development of the model involved the study and analysis of hydrogeologic conditions, agricultural and urban water demands, agricultural and urban water supplies, and an evaluation of regional water quality conditions. The Historical ESJWRM has undergone nine updates to date, of which three were major updates:

1. Major Update: Development and Calibration of Historical ESJWRM Version 1.1 (WY 1995 through 2015) for November 2020 GSP

2. Extension of Data in Historical ESJWRM Version 1.1 from WY 2016 through 2019 for WY 2019 Annual Report

3. Extension of Data in Historical ESJWRM Version 1.1 through WY 2020 for WY 2020 Annual Report

4. Major Update: Model Update and Recalibration Resulting in Historical ESJWRM Version 2.0 (WY 1995 through 2020) for Revised June 2022 GSP

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6. Updated Monthly Agricultural Demand Distribution in Fall 2022 Resulting in Historical ESJWRM Version 2.2

7. Extension of Data in Historical ESJWRM Version 2.2 through WY 2022 for WY 2022 Annual Report

8. Extension of Data in Historical ESJWRM Version 2.2 through WY 2023 for WY 2023 Annual Report

9. Major Update: Model Update and Recalibration Resulting in Historical ESJWRM Version 3.0 for 2024 Periodic Evaluation and GSP Amendment
Only ESJWRM Version 3.0 water budget results are presented in Section 2.4. Version 3.0 development is documented in a report, “Eastern San Joaquin Water Resources Model (ESJWRM) Version 3.0 Update,” published in August 2024 and available in Appendix 2-C.

Consistent with CCR Title 23 § 354.18, the water budgets presented in this document encompass the combined surface and groundwater system of the Eastern San Joaquin Subbasin. The Subbasin water budget focuses on the full water year (12 months spanning October 1 of the previous year to September 30 of the year in question), with some consideration of monthly variability.

The Regulations require that the annual water budget quantify three different conditions: historical, current, and projected. Budgets are developed to capture typical conditions during these time periods. Typical conditions are developed through selecting historical hydrologic periods that incorporate droughts, wet periods, and normal periods.

By incorporating these varied conditions within the budgets, the Subbasin is analyzed under certain hydrologic conditions, such as drought or very wet events, along with long-term averages. This Plan relies on historical hydrology to identify time periods for water budget analysis and uses the ESJWRM and associated data to develop the water budget and resulting budget estimates. The water budget components developed for the Eastern San Joaquin Subbasin are based upon estimates developed from historical and projected data as well as modeling assumptions.

The water budget assumptions may be refined in the future, the water budget may change, and the conclusions and recommendations derived from the water budget may also change.

2.4.2 Identification of Hydrologic Periods
The historical hydrologic periods used in this Plan were selected to meet the requirements of developing historical, current, and projected water budgets. The Regulations require that the projected water budget reflect a 50-year hydrologic period in order to project how the Subbasin’s land and groundwater systems may react under long-term average hydrologic conditions. Consistent with the Regulations, the ESJWRM Version 3.0’s 55-year historical record characterizes future conditions with respect to precipitation, evapotranspiration, and streamflow. Historical precipitation or rainfall in the Eastern San Joaquin Subbasin was used to identify a hydrologic period that would provide a representation of wet and dry periods and long-term average conditions needed for water budget analyses. Rainfall data for the Subbasin are derived from the PRISM (Precipitation-Elevation Regressions on Independent Slopes Model) dataset of the DWR’s California Simulation of Evapotranspiration of Applied Water (CALSIMETAW) model.

Precipitation-Elevation Regressions on Independent Slopes Model (PRISM) is a spatial estimation of rainfall data developed using monitoring network point data and interpolated using a variety of factors (Oregon State University, 2023).

Wet and dry hydrologic periods were identified by evaluating the cumulative departure from mean precipitation. Under this method, the long-term average precipitation is subtracted from annual precipitation within each water year to develop the departure from mean precipitation for each water year. Wet years have a positive departure and dry years have a negative departure; a year with exactly average precipitation would have zero departure. Starting at the first year analyzed, the departures are added cumulatively for each year. So, if the departure for Year 1 is 5 inches and the departure for Year 2 is -2 inches, the cumulative departure would be 5 inches for Year 1 and 3 inches (5 plus -2) for Year 2. Figure 2-108 graphically illustrates the cumulative departure of the spatially averaged rainfall within the Eastern San Joaquin Subbasin. The figure includes bars displaying annual precipitation for each water year from 1969 through 2023 and a horizontal line representing the mean precipitation of 15.6 inches. The cumulative departure from mean precipitation is based on these data sets and is displayed as a line that highlights wet periods with upward slopes EXHIBIT 1
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(positive departure) and dry periods with downward slopes (negative departure). More severe events are shown by steeper slopes and greater changes. For example, the period from 1975 to 1977 illustrates a short period with dramatically dry conditions (6-inch decline per year in cumulative departure).

The PRISM estimates for rainfall in the Subbasin were confirmed by comparing the cumulative departure from mean precipitation results to the water year types in the San Joaquin Valley Water Year Hydrologic Classification (CA DWR, 2023), which classifies water years 1901 through 2023 as wet, above normal, below normal, dry, and critical based on inflows to major reservoirs or lakes. Wet (W) or Above Normal (AN) years generally show upward sloping cumulative departures, while Below Normal (BN), Dry (D), or Critical (C) water year types show downward trending cumulative departures (Figure 2-108). As the San Joaquin Valley Water Year Hydrologic Classification determines water year types based on inflows for streams throughout the entire San Joaquin Valley, a more locally relevant index to the Subbasin may be developed in the future.

Figure 2-108: 55-Year Historical Precipitation and Cumulative Departure from Mean Precipitation

2.4.3 Use of the ESJWRM and Associated Data in Water Budget Development This Plan developed water budgets utilizing the ESJWRM, a fully integrated surface and groundwater flow model covering the Eastern San Joaquin Subbasin, as well as the Cosumnes Subbasin to the north and the Modesto Subbasin to the south. The adjacent subbasins were included in the ESJWRM boundaries to be consistent with past local modeling efforts and to better simulate boundary flows to/from the north and south of the Subbasin. This Plan provides a water budget for the Eastern San Joaquin Subbasin portion of the ESJWRM.

With the ESJWRM Version 3.0 as the underlying framework, four model scenarios were developed representing historical, current, projected, and projected with climate change conditions in the Eastern San Joaquin Subbasin, as discussed below:
• Historical water budget represents the historical model calibration period, which covers water years 1996 through 2023 (28 years).

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• Current water budget represents an estimate of averaged recent historical conditions in the Subbasin, based on water years 2019 through 2023 (5 years).
• Projected water budget represents estimated long-term conditions of the Subbasin under the foreseeable future level of development over a long-term period of hydrologic conditions (the 55-year period represented by water years 1969 through 2023).
• Projected water budget, with climate change represents the projected water budget, with the impacts of climate change on streamflow, evapotranspiration, and precipitation.

2.4.4 Water Budget Definitions and Assumptions
Definitions and assumptions for the historical, current, and projected water budgets are provided in the sections below and summarized in Table 2-13
.

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Table 2-13: Summary of Water Budget Assumptions (Historical, Current, and Projected Periods) Water Budget Type Historical5 Current Projected5 Projected with Climate Change5
Model Version
Historical
ESJWRM
Version 3.0
Historical
ESJWRM
Version 3.0

ESJWRM PCBL
Version 3.0

ESJWRM PCBL-CC
Version 3.0
Scenario Historical
Calibration
Current
Conditions
Projected
Conditions
Baseline
Projected Conditions
Baseline with Climate
Change
Hydrologic Years Water Years
1996-2023
Water Years
2019-2023
Water Years
1969-2023
Water Years 1969-
2023 with perturbation
Level of
Development1 Historical Current
General Plan or
Sphere of
Influence
Buildout
General Plan or Sphere
of Influence Buildout
Agricultural Demand2 Historical
Current
(average of
WY 2019-
2023)
Current (2022,
less urban
expansion)
Current (2022, less
urban expansion, with
increased ET)
Urban Demand3 Historical Current Projected based
on UWMP data
Projected based on
UWMP data
Water Supplies4 Historical Current
Projected based
on local
information
Projected based on
local information (with
an adjustment for
climate change impact
on precipitation and
streamflow)
Notes:
1 The level of development describes the footprint of the urban areas. Historical is the footprint in the historical model period (water years 1996-2023), current is the footprint at the end of the historical model period (water years 2019-2023), and projected reflects the footprint after general plan or sphere of influence urban buildout (approximately water year 2040).
2 Agricultural demand is based on historical cropping patterns and evapotranspiration rates. Projected agricultural cropping patterns are assumed to be consistent with DWR’s statewide crop mapping of 2022, less urban buildout.

For the current and projected water budgets, future evapotranspiration rates are assumed to remain the same as historical.
3 Historical urban demand includes actual demand and population from Urban Water Management Plans (UWMPs) or other planning efforts. Current demand is assumed to represent average demands and population between WY 2019-2023. Projected demand uses projected demand and population from UWMPs or other planning efforts and uses numbers for a buildout level of development (approximately water year 2040). 4 Historical water supplies rely on local district information and records. Projected water supplies were assumed for approximately water year 2040 and may include projects or expansions of supplies currently begun or with funding secured. Current water supplies represent water supplies averaging approximately water years 2019-2023 in the historical records.
5 For more information on historical and projected modeling, see the published model report (Appendix 2-C).

2.4.4.1 Assumptions Used in the Historical Water Budget The historical water budget is intended to evaluate availability and reliability of past surface water supply deliveries, aquifer response to water supply, and demand trends relative to water year type. The historical calibration of the ESJWRM reflects the historical conditions in the Eastern San Joaquin Subbasin over water years 1996-2023. The hydrologic period has an average annual precipitation of approximately 15.5 inches and includes the recent 2012-2015 and 2020-2022 droughts, the wetter years of 1996-2000, 2017, and 2023, and periods of normal precipitation.

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Regulations require the use of a minimum of 10 years to develop the historical water budget. The entire historical calibration period of the ESJWRM was used to be inclusive of all the data used in developing the ESJWRM and to average over a broader range of different hydrologic conditions. The historical water budget applied an evolving level of development and agricultural demand throughout a 28-year historical hydrology.

Additional details of the data used in the development of the historical calibration can be found in the published model report (Appendix 2-C).

The historical calibration includes the following:
• Hydrologic period: Water Years 1996-2023 (28-year hydrology) • Stream Flows for Water Years 1996-2023:
o Dry Creek: No streamflow gaging stations were available for Dry Creek; as such, flow estimates from the DWR’s California Central Valley surface and groundwater Model (C2VSim-FG v1.01) were used for water years 1996-2015 . For 2015-2023, an average of historical data by month and water year type was used. o Mokelumne River: Historical records from USGS (Mokelumne River below Camanche Dam, CA) o Calaveras River: New Hogan Dam releases
o Stanislaus River: Historical records from USGS (Stanislaus River below Goodwin Dam near Knights Ferry, CA)
o San Joaquin River: Historical records from USGS (San Joaquin River near Vernalis, CA) • Reservoir Operations: Upstream reservoirs regulating streamflows into the Subbasin include Pardee Reservoir and Camanche Reservoir on the Mokelumne River; New Hogan Reservoir on the Calaveras River; and New Melones Reservoir, Tulloch Reservoir, and Goodwin Reservoir on the Stanislaus River. As reservoir releases are regulated, no changes to the historical operations of the reservoirs are assumed. In addition, two other local reservoirs are included in the model: Woodward and Farmington. The model estimates seepage contributions from these reservoirs to the groundwater system. Water supply deliveries from these reservoirs are based on records provided by the agencies responsible for operation of these reservoirs. • Land use and cropping patterns are based on the DWR land use surveys (assumed to represent water year 1995), and the recent, comprehensive, and Subbasin-wide land use survey from DWR as prepared by Land IQ from 2016-2022 (CA DWR, 2014). Local data and information were also utilized to refine and update the cropping patterns, as needed. To fill the gap between 1995 and 2016, all land use and crop categories were interpolated at the spatial resolution level of the model elements to simulate the geographic distribution of various crops.
• Urban water demand is calculated for all the urban areas in the model. Urban centers in Eastern San Joaquin Subbasin are City of Escalon, Linden, Lockeford, City of Lodi, City of Manteca, City of Ripon, and City of Stockton. Demands for other domestic areas are estimated based on rural population. Urban water demand is based on:
o Urban water use from 2020 Urban Water Management Plans (Cal Water; Calaveras County Water District [CCWD], Cities of Lodi, Manteca, and Stockton; Stockton East Water District [SEWD]; and South San Joaquin Irrigation District [SSJID]) or municipal pumping records, used to calculate the per capita water use for each urban center.
o Urban center population from Urban Water Management Plans (UWMPs), United States Census Bureau, or the California Department of Finance.

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• Surface Water Deliveries:
o Deliveries to agricultural areas: Obtained from agricultural entities in the Subbasin, including Central San Joaquin Water Conservation District (CSJWCD), North San Joaquin Water Conservation District (NSJWCD), Oakdale Irrigation District (OID), SEWD, SSJID, and Woodbridge Irrigation District (WID) o Deliveries to urban areas: Cities of Lodi, Manteca, and Stockton (including Cal Water and City of Stockton service areas, and unincorporated San Joaquin County areas) o Recharge projects: SEWD’s Farmington Groundwater Recharge Program; NSJWCD’s Tracy Lakes Recharge Project; NSJWCD’s CALFED groundwater recharge project; Tecklenburg Recharge Project; and NSJWCD’s FloodMAR recharge projects
o Riparian diversions: CCWD, Delta areas, and data from C2VSim-FG for riparian diversions off major streams (Dry Creek, Mokelumne River, Calaveras River and related streams, Stanislaus River, San Joaquin River) (C2VSim-FG v1.01)
• Groundwater Pumping:
o District pumping for agricultural/landscape uses: City of Manteca, OID, City of Ripon, and SSJID o District pumping for urban uses: Cal Water, City of Escalon, Linden County WD, Lockeford CSD, City of Lodi, City of Manteca, City of Ripon, SEWD, and City of Stockton o Data on private pumping was not available on a consistent basis across the model, so private pumping was estimated as that which would be required to meet agricultural and rural residential water needs as calculated by the ESJWRM model based on consumptive use methodology (Refer to the ESJWRM documentation for details).

2.4.4.2 Assumptions Used in the Current Water Budget
A current conditions estimate using the Historical ESJWRM Version 3.0 was developed for use in estimating the current water budget. The current conditions estimate is comprised of the average of historical model water years 2019-2023 in order to estimate current inflows and outflows for the Subbasin. Current conditions are not necessarily indicative of one year and are instead a compilation of data assumed representative of Subbasin recent conditions. The definition of current conditions, by nature, will continuously change. The current water budget represents the current conditions as of the time of the 2024 GSP.

2.4.4.3 Assumptions Used in the Projected Water Budget
The projected water budget is intended to assess the conditions of the Subbasin under future conditions of water supply and agricultural and urban demand, including quantification of uncertainties in the components. The projected conditions scenario applies future land and water use conditions and uses the 55-year hydrologic period of water years 1969-2023. Projections are assumed to represent a buildout level of development (approximately year 2040) and are represented using projected population, land use, and water demand and supply projections. Results of the projected conditions scenario under potential climate change conditions (changes to precipitation, stream flows, and evapotranspiration) are presented in Section 2.4.4.4.

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The projected conditions scenario includes the following conditions:
• Hydrologic Period: Water Years 1969-2023 (55-year hydrology) • Stream Flows for Water Years 1969-2023:
o Dry Creek: No streamflow gaging stations were available for Dry Creek; as such, flow estimates from the DWR’s C2VSim-FG were used (C2VSim-FG v1.01)
o Mokelumne River: Historical records from USGS (Mokelumne River below Camanche Dam, CA) o Calaveras River: Historical records from USGS (Calaveras River below New Hogan Dam near Valley Springs, CA) and New Hogan Dam releases
o Stanislaus River: Historical records from USGS (Stanislaus River below Goodwin Dam near Knights Ferry, CA)
o San Joaquin River: Historical records from USGS (San Joaquin River near Vernalis, CA) • Reservoir Operations: Upstream reservoirs regulating streamflows into the Subbasin include Pardee Reservoir and Camanche Reservoir on the Mokelumne River; New Hogan Reservoir on the Calaveras River; and New Melones Reservoir, Tulloch Reservoir, and Goodwin Reservoir on the Stanislaus River. The projected conditions scenario assumes that the historical operations of the reservoirs over the 50-year hydrologic records were in place and no changes are made. • Land use and cropping patterns are based on the most recent, comprehensive, and Subbasin-wide land use survey from DWR as prepared by Land IQ (CA DWR, 2014), with adjustments based on local information and input. Urban areas expand to either the sphere of influence or general plan boundaries and are held constant during the simulation. Cropping acreage is reduced only where urban expansion occurs. • Urban water demands are calculated for all the urban areas in the model. Urban centers in Eastern San Joaquin Subbasin are City of Escalon, Linden, Lockeford, City of Lodi, City of Manteca, City of Ripon, and City of Stockton. Demands for other domestic areas are estimated based on rural population. Urban water demand is based on:
o Urban water use estimated from projections in the 2020 Urban Water Management Plans (Cal Water; CCWD, Cities of Lodi, Manteca, Ripon, and Stockton; SEWD; and SSJID) or municipal pumping records, used to calculate the per capita water use for each urban center in the future (approximately 2040 or 2045).
o Urban center population projections from the San Joaquin Council of Governments. • Surface water delivery projections for the 55-year period were estimated based on the historical records of diversions by water year type, surface water rights or agreements, and potential planned changes/upgrades to the surface water diversion facilities. Surface water diversion estimates reflecting projected conditions using currently available information and knowledge were provided to each GSA for review and comment, and appropriate adjustments were made to the estimated record to reflect the surface water diversion projections for each entity. Surface water deliveries include:
o Deliveries to agricultural areas: CSJWCD, NSJWCD, OID, SEWD, SSJID, and WID o Deliveries to urban areas: Cities of Lodi, Manteca, and Stockton (including Cal Water and City of Stockton service areas, and unincorporated San Joaquin County areas) EXHIBIT 1
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o Recycling or recharge projects: Recycled water for Cities of Lodi and Manteca; SEWD’s Farmington Groundwater Recharge Program; NSJWCD’s Tracy Lakes Recharge Project; and NSJWCD’s CALFED groundwater recharge project
o Riparian: CCWD, Delta areas, and data from C2VSim for riparian diversions off major streams (Dry Creek, Mokelumne River, Calaveras River, Stanislaus River, and San Joaquin River) • As private groundwater pumping was estimated by ESJWRM in the historical calibration, there is no local estimate of projected private groundwater pumping available on a consistent basis across the model.

Therefore, groundwater pumping to meet agricultural and rural residential needs is calculated by the model based on meeting remaining demands after surface water deliveries are made. Demand in areas with no access to surface water is completely met by groundwater pumping. Additional details on the estimation of private groundwater pumping in ESJWRM can be found in the published model report (Appendix 2-A).

Additional details of the data used in the development of the projected conditions baseline can be found in the published model report (Appendix 2-C).

2.4.4.4 Assumptions Used in the Projected Water Budget, with Climate Change The projected water budget with climate change is intended to assess the conditions of the Subbasin under future conditions of water supply and agricultural and urban demand, with the additional impact of climate change on the available water supply and agricultural demand. The projected conditions scenario with climate change is based on the projected conditions scenario without climate change and therefore all assumptions listed in Section 2.4.4.3 remain, except where noted below. A future scenario of 2070 climate forecasts was evaluated in this analysis, consistent with DWR guidance. DWR combined 10 global climate models (GCMs) for two different representative climate pathways (RCPs) to generate the central tendency scenarios in the datasets used in this analysis. The “local analogs” method (LOCA) was used to downscale these 20 different climate projections to a scale usable for California (DWR, 2018a).

The 2070 central tendency (2070 CT) among these projections serves to assess impacts of climate change over the long-term planning and implementation period.

The following model inputs were adjusted in the 2070 CT climate change scenario:
• Stream Flow: Flows for Central Valley rivers are divided into impaired and unimpaired. In the Subbasin, Dry Creek and Mokelumne River are unimpaired rivers. Projected conditions scenario stream flows are modified by applying perturbation factors provided by DWR. Calaveras, San Joaquin, and Stanislaus Rivers are all impaired rivers. CalSim II estimated flows, also provided by DWR, were used to simulate stream flows under climate change for impaired rivers.
• Precipitation: Precipitation was modified using the perturbation factors provided by DWR, where available. • Evapotranspiration: Evapotranspiration (ET) was modified using the perturbation factors provided by DWR, where available.

Additional details of the data used in the development of the projected conditions with climate change scenario can be found in the published model report (Appendix 2-C).

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2.4.4.5 Updates to Water Budgets
Following submittal of the Eastern San Joaquin Subbasin GSP in January of 2020, the ESJWRM was revised to correct data relating to historical surface water deliveries and to include additional data for Water Year (WY) 2016 through WY 2023. Specifically, the following data sets were updated in ESJWRM:
• The hydrologic period was extended to include WY 2016-2023 with the precipitation data mapped accordingly. • Model layering was updated based on Airborne Electromagnetic (AEM) data • Changes to land use were made with the simulated land uses mapped to the statewide crop mapping released by DWR in 2016 through 2022. USDA CropScape data was removed from the model and interpolation was updated from 1995 to 2016 datasets.
• Stream inflows were extended through WY 2023 using the same data sources as in the original version. • Populations were updated for WY 2016 through 2023, and urban demands revised accordingly. Rural residential urban demand was updated to use
• Surface water deliveries were extended to WY 2023 and additional surface water deliveries that were not previously simulated were added to the model, including Farmington Reservoir seepage. • Groundwater pumping volumes were extended to WY 2023 and the Modesto Subbasin wells, additional OID, Cal Water, Manteca, and SSJID wells were added to the model. • Agricultural water operations were updated to extend through WY 2023.

The ESJWRM simulation period was extended to simulate Water Years 1995 through 2023 and the model recalibrated for the extended period. As a result of the two major model updates, both the historical and projected water budgets were revised in 2021 and 2024 to reflect the new data sets used in the model. See Appendix 2-C for additional details on the updates made to the ESJWRM.

2.4.5 Water Budget Estimates
The ESJWRM simulates the major hydrologic processes that affect the land surface, stream, and groundwater systems in the Eastern San Joaquin Subbasin. The major hydrologic processes can be represented by separate water budgets which detail inflows and outflows occurring at the stream scale (budget on surface water flows occurring in the Subbasin), land surface scale (budget balancing how demands on urban, agricultural, and native lands are met by rainfall, surface water deliveries, or groundwater pumping), and groundwater scale (budget detailing flows occurring within the groundwater aquifers of the Subbasin).

The primary components of the stream system are:
• Inflows:
o Stream inflows
o Stream gain from the groundwater system
o Runoff to the stream system from precipitation
o Return flow to the stream system from irrigation water • Outflows:

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o Stream outflows
o Stream seepage (i.e., losses to the groundwater system) o Surface water diversions
o Riparian intake from streams
The primary components of the land surface system are:
• Inflows:
o Precipitation
o Surface water supplies to meet agricultural or urban and industrial uses o Groundwater pumping (i.e., groundwater supplies to meet agricultural or urban and industrial uses) o Riparian intake from streams
• Outflows:
o Evapotranspiration
o Runoff to the stream system
o Return flow to the stream system
o Deep percolation from precipitation, applied water (surface water and groundwater) for agricultural lands, and applied water (surface water and groundwater) for outdoor use in the urban areas or industrial purposes
The primary components of the groundwater system are:
• Inflows:
o Deep percolation from precipitation, applied water (surface water and groundwater) for agricultural lands, and applied water (surface water and groundwater) for outdoor use in the urban areas or industrial purposes
o Stream seepage (i.e., losses to the groundwater system) o Other recharge (including unlined canals/reservoir seepage, local tributaries seepage, and Managed Aquifer Recharge [MAR] projects)
o Subsurface inflow
• Outflows:
o Groundwater outflow to streams (i.e., stream gain from the groundwater system) o Groundwater pumping
o Subsurface outflow
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• Change in Groundwater Storage (Inflows Minus Outflows): This reflects average annual change in groundwater storage
The revised ESJWRM Version 3.0 estimated water budgets for the historical, current conditions, projected conditions, and projected conditions with climate change scenarios are provided below, with results summarized in Table 2-14 through Table 2-16. Differences between the original and revised scenarios are discussed further in the documentation in Appendix 2-C.

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Table 2-14: Average Annual Water Budget for Revised ESJWRM (Version 3.0) – Stream System (AF/year)
Component
Historical
Calibration
(AF/year)
Current
Conditions
(AF/year)
Projected
Conditions
(AF/year)
Projected
Conditions with
Climate Change
(AF/year)
Model Version
Historical
ESJWRM Version

3.0 Historical
ESJWRM Version

3.0 ESJWRM PCBL
Version 3.0
ESJWRM PCBLCC Version 3.0
Hydrologic Period
Water Years
1996-2023
(28-Year period)
Water Years
2019-2023
(5-Year average)
Water Years
1969- 2023
(55-Year period)
Water Years
1969- 2023
(55-Year period)
Inflows
Stream Inflows1 4,221,000 4,224,000 4,519,000 4,929,000 Stream Gain from
Groundwater2
145,000 130,000 121,000 115,000
Eastern San Joaquin
Subbasin 75,000 63,000 57,000 53,000
Dry Creek11 0 0 0 0
Mokelumne River 14,000 13,000 10,000 8,000
Calaveras River 1,000 1,000 1,000 1,000
Stanislaus River 28,000 18,000 17,000 16,000
San Joaquin River 31,000 31,000 29,000 27,000
Other Subbasins4 70,000 67,000 65,000 62,000
Dry Creek 23,000 29,000 28,000 27,000
Mokelumne River 0 0 0 0
Stanislaus River 27,000 19,000 17,000 16,000
San Joaquin River 20,000 20,000 19,000 18,000
Runoff to the Stream System5 629,000 741,000 656,000 753,000 Return Flow to Stream System6 96,000 95,000 111,000 112,000 Total Inflow10 5,092,000 5,190,000 5,407,000 5,908,000
Outflows
Stream Outflows7 4,426,000 4,469,000 4,655,000 5,108,000 Stream Seepage2 284,000 331,000 374,000 420,000
Eastern San Joaquin
Subbasin 236,000 267,000 298,000 330,000
Dry Creek 2,000 2,000 2,000 2,000
Mokelumne River 125,000 135,000 150,000 160,000
Calaveras River 37,000 37,000 39,000 41,000
Stanislaus River 36,000 55,000 67,000 82,000
San Joaquin River 37,000 37,000 40,000 45,000
Other Subbasins4 47,000 65,000 76,000 90,000
Dry Creek 2,000 2,000 2,000 2,000
Mokelumne River 3,000 3,000 3,000 4,000
Stanislaus River 30,000 47,000 56,000 69,000
San Joaquin River 12,000 12,000 14,000 14,000
Surface Water Diversions8 340,000 353,000 340,000 340,000 EXHIBIT 1
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Riparian Intake from Streams9 42,000 37,000 37,000 40,000 Total Outflow10 5,092,000 5,190,000 5,407,000 5,908,000 Notes:
1 Stream inflows into Eastern San Joaquin Subbasin include flows from Dry Creek, Mokelumne River, Calaveras River, Stanislaus River, San Joaquin River, and estimated tributary flows. Differences between historical and current/projected flows are due to differing hydrologic periods.
2 Stream gain from groundwater and stream seepage represent the interaction of surface water and groundwater. Differences between the scenarios are related to differences in streamflows and long-term average groundwater elevations. Projected scenarios and even current condition averages represent lower groundwater levels, causing less stream interaction. 3 Local tributaries include Bear Creek and related streams, Little Johns Creek, Duck Creek, and Lone Tree Creek. 4 Other subbasins include the Cosumnes, Modesto, South American, Solano, East Contra Costa, and Tracy Subbasins. Streamaquifer interaction with the other subbasins was included for streams on the boundaries of the Eastern San Joaquin Subbasin. 5 Runoff to the stream system is due to precipitation. As urban areas are assumed to have greater runoff of precipitation (due to more paved areas), the changes in runoff between the model scenarios are due to differences in the urban areas in the scenarios, as well as the amount of precipitation occurring. The historical calibration, with both less precipitation (due to more dry years than wet in the 28-year period) and smaller urban areas, has a corresponding smaller runoff. The current conditions scenario uses urban areas at the end of the historical calibration, while the projected scenario includes urban buildout to sphere of influence or general plan boundaries and therefore has more runoff. 6 Return flow to the stream system is due to applied water, either surface water or groundwater used for agricultural or municipal purposes. Differences between the scenarios is primarily related to the urban growth in the projected conditions scenario causing higher urban demand and therefore correspondingly higher applied water to meet that demand resulting in greater urban return flows (i.e., discharge of treated wastewater).
7 Stream outflows occur at the edge of Eastern San Joaquin Subbasin at the confluence of the San Joaquin and Mokelumne Rivers.
8 Surface water diversions shown in this table are the volumes of water taken directly off the river prior to any losses due to evaporation or canal seepage. These numbers do not include surface water directly diverted from simulated stream nodes (i.e., water taken off Stanislaus River occurs just upstream in the Subbasin). Differences between scenarios are due to differences in historical, current, and planned surface water diversions. 9 Riparian intake from streams is the portion of the riparian vegetation evapotranspiration met by streamflows. Differences between scenarios may be due to availability of streamflows or extent of riparian vegetation, which may be affected by growth in urban areas.
10 Summations in table may not match the numbers in the table. This is due to the rounding of model results. 11 Values smaller than 500 AF/year are represented by a dash (-).

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Table 2-15: Average Annual Water Budget for Revised ESJWRM – Land Surface System (AF/year) Component
Historical
Calibration
(AF/year)
Current
Conditions
(AF/year)
Projected
Conditions
(AF/year)
Projected
Conditions with
Climate Change
(AF/year)
Model Version
Historical
ESJWRM
Version 3.0
Historical
ESJWRM
Version 3.0

ESJWRM PCBL
Version 3.0
ESJWRM PCBLCC Version 3.0
Hydrologic Period
Water Years
1996-2023
(28-Year period)
Water Years
2019-2023
(5-Year average)
Water Years
1969- 2023
(55-Year period)
Water Years
1969- 2023
(55-Year period)
Inflows
Precipitation1
(Precipitation, inches)
988,000
(15.5)
1,063,000
(16.7)
992,000
(15.6)
1,087,000
(17.1)
Total Surface Water Supply2 568,000 562,000 525,000 525,000 Agricultural 512,000 497,000 452,000 452,000
Urban and Industrial 56,000 65,000 73,000 73,000
Total Groundwater Supply3 732,000 830,000 799,000 879,000 Agricultural 666,000 777,000 732,000 812,000
Urban and Industrial 66,000 53,000 67,000 67,000
Riparian Intake from Streams4 30,000 26,000 26,000 29,000 Total Inflow10 2,318,000 2,481,000 2,342,000 2,521,000
Outflows
Evapotranspiration5 1,309,000 1,352,000 1,302,000 1,384,000 Agricultural 1,006,000 1,080,000 999,000 1,089,000
Municipal and Domestic 59,000 58,000 80,000 81,000
Refuge, Native, and Riparian 243,000 213,000 214,000 214,000 Runoff to the Stream System6 629,000 741,000 656,000 753,000 Return Flow to the Stream System7 96,000 95,000 111,000 112,000 Agricultural 22,000 22,000 25,000 26,000
Municipal and Domestic 75,000 73,000 86,000 86,000
Deep Percolation8 275,000 284,000 270,000 268,000
Precipitation 60,000 53,000 55,000 52,000
Applied Surface Water –
Agricultural 85,000 82,000 73,000 70,000
Applied Surface Water – Urban
and Industrial 9,000 11,000 12,000 11,000
Applied Groundwater –
Agricultural 111,000 129,000 119,000 125,000
Applied Groundwater – Urban and
Industrial 11,000 9,000 11,000 10,000
Other Flows9 8,000 9,000 4,000 5,000
Total Outflow10 2,318,000 2,481,000 2,342,000 2,521,000 Notes:
1 Precipitation is discussed in the identification of the hydrologic periods in 2.4.2. The projected conditions scenarios utilize the same 55 years of hydrology (water years 1969-2023) with perturbations in the climate change scenario causing more precipitation. The historical calibration has a shorter hydrologic period (28 years from 1996-2023) with slightly less precipitation on average. Current conditions represent recent years with 2 wet years (2019 and 2023) and 3 dry or critical years (2020, 2021, and 2022).

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2 Total surface water supply shown in this table is the volume of surface water diverted or transported to meet agricultural and urban demands minus estimated losses due to evaporation or canal seepage. Differences between scenarios are due to differences in historical, current, and planned surface water deliveries. 3 Total groundwater supply in the scenarios is calculated based on meeting remaining demands after surface water deliveries occur. Differences in demand largely drive the amount of groundwater pumped. 4 Riparian intake from streams is the portion of the riparian vegetation evapotranspiration met by streamflows. Differences between scenarios may be due to availability of streamflows or extent of riparian vegetation, which may be affected by growth in urban areas.
5 Evapotranspiration is the demand required by agricultural land (i.e., crops); municipal and domestic areas (i.e., industrial and urban demands); and refuge, native and riparian areas. Differences in evapotranspiration are largely related to differences in urban areas between the scenarios and the loss of agricultural or native/riparian land as urban growth occurs. 6 Runoff to the stream system is due to precipitation. As urban areas are assumed to have greater runoff (e.g., more paved areas), the changes in runoff between the model scenarios are due to differences in the urban areas in the scenarios, as well as the amount of precipitation occurring. The historical calibration, with both less precipitation and smaller urban areas, has a corresponding smaller runoff. The current conditions scenario uses urban areas at the end of the historical calibration, while the projected scenario includes urban buildout to sphere of influence or general plan boundaries and therefore has more runoff. 7 Return flow to the stream system is due to applied water, either surface water or groundwater used for agricultural or municipal purposes. Differences between the scenarios is primarily related to the urban growth in the projected conditions scenario causing higher urban demand and therefore correspondingly higher applied water to meet that demand. 8 Deep percolation is the amount of infiltrated water ultimately reaching the groundwater aquifer. The source of the water may be from precipitation or either applied surface water or groundwater used for agricultural or urban and industrial purposes.

Differences between scenarios are related to differences between these sources of water and differences in the infiltration parameters related to land use.
9 Other Flows captures the gains and losses due to land expansion and temporary storage in the root-zone and unsaturated (vadose) zones.
10 Summations in table may not match the numbers in the table. This is due to the rounding of model results.

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Table 2-16: Average Annual Water Budget for Revised ESJWRM – Groundwater System (AF/year) Component
Historical
Calibration
(AF/year)
Current
Conditions
(AF/year)
Projected
Conditions
(AF/year)
Projected
Conditions with
Climate Change
(AF/year)
Model Version
Historical
ESJWRM
Version 3.0
Historical
ESJWRM
Version 3.0

ESJWRM PCBL
Version 3.0
ESJWRM PCBLCC Version 3.0
Hydrologic Period
Water Years
1996-2023
(28-Year period)
Water Years
2019-2023
(5-Year average)
Water Years
1969- 2023
(55-Year period)
Water Years
1969- 2023
(55-Year period)
Inflows
Deep Percolation1 275,000 284,000 270,000 268,000
Precipitation 60,000 53,000 55,000 52,000
Applied Surface Water – Agricultural 85,000 82,000 73,000 70,000 Applied Surface Water – Urban and
Industrial 9,000 11,000 12,000 11,000
Applied Groundwater – Agricultural 111,000 129,000 119,000 125,000 Applied Groundwater – Urban and
Industrial 11,000 9,000 11,000 10,000
Stream Seepage2 236,000 267,000 298,000 330,000
Dry Creek 2,000 2,000 2,000 2,000
Mokelumne River 125,000 135,000 150,000 160,000
Calaveras River 37,000 37,000 39,000 41,000
Stanislaus River 36,000 55,000 67,000 82,000
San Joaquin River 37,000 37,000 40,000 45,000
Other Recharge 170,000 174,000 165,000 168,000
Carriage/Canal Recharge 103,000 109,000 98,000 98,000
Managed Aquifer Recharge 5,000 9,000 11,000 11,000
Reservoir Seepage 17,000 14,000 14,000 14,000
Ungauged Watershed Drainage 45,000 42,000 45,000 48,000 Subsurface Inflow3 176,000 188,000 204,000 222,000
Cosumnes Subbasin 28,000 34,000 35,000 35,000
Sierra Nevada Mountains 55,000 54,000 57,000 55,000
Modesto Subbasin 30,000 32,000 37,000 41,000
South American Subbasin 3,000 4,000 5,000 6,000
Solano Subbasin 19,000 19,000 22,000 27,000
East Contra Costa Subbasin 9,000 10,000 11,000 13,000
Tracy Subbasin 31,000 34,000 37,000 44,000
Total Inflow5 857,000 912,000 937,000 988,000
Outflows
Groundwater Outflow to Streams2 75,000 63,000 57,000 53,000 Dry Creek6 0 0 0 0
Mokelumne River 14,000 13,000 10,000 8,000
Calaveras River 1,000 1,000 1,000 1,000
Stanislaus River 28,000 18,000 17,000 16,000
San Joaquin River 31,000 31,000 29,000 27,000
Groundwater Pumping4 732,000 830,000 799,000 879,000
Agricultural 666,000 777,000 732,000 812,000
Urban and Industrial 66,000 53,000 67,000 67,000
Subsurface Outflow3 96,000 104,000 110,000 111,000
Cosumnes Subbasin 27,000 32,000 36,000 37,000
Modesto Subbasin 40,000 44,000 44,000 46,000
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Component
Historical
Calibration
(AF/year)
Current
Conditions
(AF/year)
Projected
Conditions
(AF/year)
Projected
Conditions with
Climate Change
(AF/year)
Model Version
Historical
ESJWRM
Version 3.0
Historical
ESJWRM
Version 3.0

ESJWRM PCBL
Version 3.0
ESJWRM PCBLCC Version 3.0
Hydrologic Period
Water Years
1996-2023
(28-Year period)
Water Years
2019-2023
(5-Year average)
Water Years
1969- 2023
(55-Year period)
Water Years
1969- 2023
(55-Year period)
South American Subbasin6 1,000 1,000 0 0
Solano Subbasin 11,000 11,000 11,000 10,000
East Contra Costa Subbasin 2,000 2,000 2,000 2,000
Tracy Subbasin 16,000 14,000 17,000 16,000
Total Outflow5 903,000 997,000 965,000 1,043,000
Change in Groundwater Storage (Inflows Minus Outflows)
Change in Groundwater Storage5(48,000) (89,000) (30,000) (56,000) Notes:
1 Deep percolation is the amount of infiltrated water ultimately reaching the groundwater aquifer. The source of the water may be from precipitation, as well as either applied surface water or groundwater used for agricultural or urban and industrial purposes.

Differences between scenarios are related to differences between these sources of water and differences in urban versus agricultural land use totals.
2 Stream gain from groundwater and stream seepage represent the interaction of surface water and groundwater. Differences between the scenarios are related to differences in streamflows and long-term average groundwater elevations. 3 The goal of projecting inter-basin flows is to maintain a reasonable balance between the neighboring groundwater subbasins.

The resulting projected conditions scenario flows are within 10-15% of historical calibration flows, considered a reasonable range given the availability of projected land use, population, surface water delivery, and groundwater production data from areas outside of the Eastern San Joaquin Subbasin. Continuing inter-basin coordination may refine these numbers. 4 Groundwater pumping is estimated by the ESJWRM based on the need for additional water to meet remaining demands after surface water deliveries occur. Differences in demand largely drive the amount of groundwater pumped. 5 Summations in table may not match the numbers in the table. This is due to the rounding of model results. 6 Values smaller than 500 AF/year are represented by a dash (-).

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2.4.5.1 Historical Water Budget Estimates (Historical ESJWRM Version 3.0) The historical water budget is a quantitative tabulation of the historical surface and groundwater supply represented in the historical calibration of the ESJWRM covering the 28-year period of water years 1996-2023. The ESJGWA selected this period as the representative hydrologic period to calibrate and reduce the uncertainty of the ESJWRM. Proper analysis and calibration of water budgets using the ESJWRM assures the hydrologic characteristics of the groundwater basin are well simulated. The historical calibration is discussed in detail in the historical model documentation (Appendix 2-A). CCR Title 23 § 354.18, the water budget includes estimates for supply and demand, while summarizing flows within the Subbasin, including the movement of all primary sources of water such as precipitation, agricultural water supplies, streamflow, and subsurface flows.

Subsequent to completion and submittal of the GSP in January of 2020, the ESJWRM was updated to include new data sets extending the simulation period to encompass WY 1996 through 2020. It was then updated again in 2024 to extend the simulation period from WY 1996 through 2023. These model updates, recalibration, and the associated results are documented in Appendix 2-C of this GSP.

The existing stream network supplies water to multiple agricultural water users and municipalities in the Eastern San Joaquin Subbasin. When analyzing the water budget for the stream system, it is important to note potentially significant effects due to the interactions and managed operations of adjacent groundwater subbasins on streams coinciding with the boundaries of the Subbasin (i.e., Dry Creek, portions of the Mokelumne River, San Joaquin River, and Stanislaus River). The summary of water budget assumptions presented in Table 2-13 and Figure 2-109 not only quantifies the surface water system within the Subbasin, but also estimates contributions from adjoining subbasins.

The stream system inflows through or along the Subbasin boundary simulated in the historical calibration average is

5.1 MAF/year. The majority of these flows, almost 4.2 MAF/year, enter the Subbasin as stream inflows to the Subbasin.

Three other surface water inflows are estimated stream gains from the groundwater system (145,000 AF/year), runoff of precipitation to the stream system (629,000 AF/year), and return flow of applied water to the stream system (96,000 AF/year). Outflows of the Eastern San Joaquin Subbasin stream system total 5.1 MAF/year and include downstream outflows leaving the Subbasin (almost 4.4 MAF/year), stream seepage to the groundwater system (284,000 AF/year), surface water diversions (340,000 AF/year), and riparian vegetation intake from streams (42,000 AF/year).

Figure 2-109: Historical Average Annual Water Budget – Stream System EXHIBIT 1
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The land surface system water budget in the historical calibration of the Eastern San Joaquin Subbasin, shown below in Figure 2-110, estimates almost 2.3 MAF/year of inflows, a combination of precipitation (988,000 AF/year), surface water supply (568,000 AF/year), groundwater supply (732,000 AF/year), and riparian intake from streams (30,000 AF/year). The outflow from the land surface system in the historical calibration estimates evapotranspiration (close to 1.3 MAF/year), runoff of precipitation to the stream system (629,000 AF/year), return flow of applied water to the stream system (96,000 AF/year), deep percolation of precipitation or applied water (275,000 AF/year), and a small component representing other flows (8,000 AF/year), which includes uncertainties in other components due to land expansion and temporary storage in the root-zone and unsaturated (vadose) zones.

Figure 2-110: Historical Average Annual Water Budget – Land Surface System The groundwater system of the Eastern San Joaquin Subbasin includes 905,000 AF/year of inflows in the historical calibration (not including change in groundwater storage), of which 275,000 AF/year is deep percolation of precipitation or applied water. There is also stream seepage (236,000 AF/year), other recharge (170,000 AF/year), and subsurface inflows (176,000 AF/year) from the Sierra Nevada Mountains and the neighboring groundwater subbasins of Cosumnes, Modesto, South American, Solano, East Contra Costa, and Tracy. On average, the inflows do not meet the entire groundwater demand. The primary outflow from the groundwater system is pumping (732,000 AF/year), followed by groundwater outflow to streams (75,000 AF/year), and subsurface outflow to the neighboring groundwater subbasins (96,000 AF/year).

The Eastern San Joaquin Subbasin average historical groundwater budget has greater outflows than inflows, leading to an estimated average annual decrease in groundwater storage of approximately 48,000 AF/year. Figure 2-111 summarizes the average historical calibration groundwater inflows and outflows of the Eastern San Joaquin Subbasin.

A groundwater change in storage, or overdraft, estimate of 48,000 AF/year represents a refinement over previous efforts which have estimated levels of overdraft for the Subbasin to be between 70,000 AF and 150,000 AF annually.

Such previous efforts include the DWR’s 2003 Bulletin 118 study (CA DWR, 2003) and modeling conducting as part of the SJCFCWCD’s 2001 Water Management Plan (SJCFCWCD, 2001) and presented in the 2004 Eastern San Joaquin Groundwater Basin Groundwater Management Plan (NSJCGBA, 2004). The analysis presented in this Plan represents the best available information to date. These estimates, which are the result of several years of collaboration between EXHIBIT 1
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agencies prior to Plan development, utilize new data and modeling capabilities not captured in prior modeling efforts.

A portion of the reduction seen in the overdraft estimate is also the result of converting from groundwater use to surface water supplies that has occurred since the development of previous estimates. For additional discussion of refinements that occurred in the development of the ESJWRM (Woodard & Curran, 2018), see Appendix 2-A.

Figure 2-111: Historical Average Annual Water Budget Estimates – Groundwater System Historical inflows and outflows change by water year type as defined by the San Joaquin Valley Water Year Hydrologic Classification (CA DWR, 2018a). In wet years, precipitation meets more of the water demand and greater availability of surface water reduces the need for groundwater pumping. However, in dry years, more groundwater is pumped to meet the demand not met by surface water or precipitation. This may lead to an increase in groundwater storage in wet years and a decrease in dry years. Table 2-17breaks down the average historical water supply and demand by water year type.

The historical calibration focuses on representing changing conditions and operations, such as new agricultural land or crop types, new surface water diversions, and population growth. The timing of these changes is often independent of the hydrologic conditions of the year in question; therefore, looking at supplies and demands averaged by water year type does not necessarily present clear results. Furthermore, the 28 years represented in the historical calibration do not include an equal number of each water year type, making averages less reliable to gather historical trends. As the projected conditions scenario considered the water year type in some of the model inputs and the 55-year hydrologic period allows for greater repetition of the water year types, the projected conditions results presented later in Section

2.4.5.3 are more consistent with the trends expected when averaging by water year type.

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Table 2-17: Average Annual Values for Key Components of Historical Water Budget by Year Type Water Year Type (San Joaquin River Index)
Component Wet Above
Normal
Below
Normal1
Dry Critical 28-Year
Number of Years2 9 3 2 7 7 28
Precipitation, AF/year
(Precipitation, inches)
1,409,000
(22.1)
944,000
(14.8)
867,000
(13.6)
805,000
(12.6)
684,000
(10.7)
988,000
(15.5)
Water Demand (AF/year)
Ag Demand3 1,143,000 1,114,000 1,168,000 1,167,000 1,225,000 1,168,000 Urban Demand4 117,000 122,000 122,000 125,000 123,000 122,000 Total Demand7 1,260,000 1,236,000 1,290,000 1,293,000 1,348,000 1,290,000 Water Supply (AF/year)
Total Surface Water
Supply5
556,000 597,000 557,000 572,000 569,000 568,000
Agricultural 503,000 544,000 501,000 517,000 507,000 512,000 Urban and Industrial 53,000 53,000 56,000 55,000 62,000 56,000 Total Groundwater
Supply6
713,000 648,000 741,000 731,000 791,000 732,000
Agricultural 648,000 578,000 675,000 660,000 728,000 666,000 Urban and Industrial 65,000 70,000 67,000 71,000 62,000 66,000 Total Supply (AF/year)7 1,268,000 1,245,000 1,298,000 1,303,000 1,360,000 1,300,000 Change in
Groundwater Storage
(AF/year)7
78,000 13,000 -82,000 -105,000 -170,000 -48,000
Notes:
1 There was only two below normal water yeas in the historical calibration (water year 2003 and 2018), so averages are just based on model results for two water years. Since there weren’t any more below normal years to use in the average, results for the below normal water year type may not follow expected trends. 2 List of historical water budget water years by water year type:

Wet: 1996, 1997, 1998, 2005, 2006, 2011, 2017, 2019, 2023 Above Normal: 1999, 2000, 2010
Below Normal: 2003, 2018
Dry: 2001, 2002, 2004, 2009, 2012, 2016, 2020
Critical: 2007, 2008, 2013, 2014, 2015, 2021, 2022
3 Agricultural demand is based on evapotranspiration by crop and acreages by crop. As agricultural land use changes over the historical calibration through changes in crop types and urbanization, averaging of the resulting agricultural demand is less a function of water year type than of the time in the simulation when that year type fell. 4 Urban demands in the historical water budget are reported values from cited sources. Averaging urban demands by water year type may not explicitly depict urban growth patterns during the historical calibration period. 5 Total surface water supply is based on information received from local entities and varied historically based on when surface water rights or agreements occurred. As some entities received new surface water sources during the historical calibration period, averaging by water year type depends more on when the water year types occurred in the simulation. 6 Total groundwater supply is pumping as estimated by the ESJWRM is a function of demand, precipitation, and surface water.

Differences between water year types for groundwater pumping are more related to differences in these components. 7 Summations in table may not match the numbers in the table. This is due to the rounding of model results.

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2.4.5.2 Current Water Budget Estimates (Historical ESJWRM Version 3.0) The current water budget quantifies inflows to and outflows from the Subbasin using the most recent 50 years of hydrology, water supply, water demand, and land use information.

The outflows from the stream system in the current conditions scenario include 353,000 AF/year of surface water diversions occurring in the Subbasin from simulated streams. In addition, on average, over 4.5 MAF/year leaves the Subbasin’s stream system as downstream outflow of the San Joaquin River and Mokelumne River, 331,000 AF/year is lost as stream seepage to the groundwater system, and 37,000 AF/year is used by riparian vegetation as riparian intake from streams.

These demands are met by an estimated 4.2 MAF/year of stream inflows, 741,000 AF/year of runoff of precipitation to the stream system, 95,000 AF/year of return flow of applied water to the stream system, and 130,000 AF/year of stream gain from the groundwater system. Figure 2-112 summarizes the average annual inflows and outflow of the current conditions scenario in the Eastern San Joaquin Subbasin stream network.

Figure 2-112: Current Average Annual Water Budget Estimates – Stream System EXHIBIT 1
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Over the 5-year recent hydrologic period, the current conditions land surface water budget shows average annual inflows of almost 2.5 MAF/year, including 1.1 MAF/year of precipitation, 1.4 MAF/year of applied water (562,000 AF/year of surface water supply and 830,000 AF/year of groundwater supply), and 26,000 AF/year of riparian intake from the stream system. Approximately 2.5 MAF/year of outflows include evapotranspiration (1.4 MAF/year), runoff to the stream system of precipitation (741,000 AF/year), return flow to the stream system of applied water (95,000 AF/year), deep percolation (284,000 AF/year), and other flows due to land expansion and temporary storage in the root-zone and vadose zones (9,000 AF/year). Figure 2-113 summarizes the average annual current conditions inflows and outflows in the land surface budget for the Eastern San Joaquin Subbasin.

Figure 2-113: Current Average Annual Water Budget Estimates – Land Surface System EXHIBIT 1
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The current conditions scenario averages 5 years of recent hydrology with conditions approximately reflective of current Subbasin management and activities., The current conditions groundwater system water budget shows average annual inflows of 1 MAF/year, including 284,000 AF/year of deep percolation, 267,000 AF/year of stream seepage, 174,000 AF/year of other recharge (including canal and reservoir seepage and MAR projects), and subsurface inflows from surrounding subbasins and the Sierra Nevada Mountains totaling 188,000 AF/year.

Similar to the historical water budget, average groundwater system outflows exceed the inflows under current conditions. Groundwater pumping (830,000 AF/year) remains the largest portion of aquifer discharge, with subsurface outflows to surrounding subbasins (104,000 AF/year) and groundwater outflow or losses to the stream system (63,000 AF/year), bringing the total system outflows to under 1 MAF/year.

The Eastern San Joaquin Subbasin’s current conditions groundwater budget has greater outflows than inflows, resulting in an average annual decline in groundwater storage of 89,000 AF/year. Figure 2-114 summarizes the average current conditions groundwater inflows and outflows in the Eastern San Joaquin Subbasin.

Figure 2-114: Current Average Annual Water Budget Estimates – Groundwater System EXHIBIT 1
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2.4.5.3 Projected Water Budget Estimates (ESJWRM PCBL Version 3.0) The projected water budget is used to estimate future baseline conditions of supply, demand, and aquifer response to Plan implementation. The projected conditions scenario of the ESJWRM is used to evaluate the projected conditions water budget assuming a 2040 level of development and using hydrology from water years 1969-2023. Results of the projected conditions scenario under potential climate change conditions (changes to precipitation, stream flows, and evapotranspiration) are presented in Section 2.4.5.4.

Subsequent to completion and submittal of the GSP in January of 2020, refinements and enhancements were made to the historical data for the updated historical ESJWRM, which in turn, required an update to the projected conditions baseline ESJWRM. The updated version of the Projected Conditions Baseline (PCBL) used the extended dataset and calibration results, along with updated data sources and assumptions for projected conditions, representing approximately WY 2040 conditions. This projected water budget update and the associated results are documented in Appendix 2-C of this revised GSP.

Development of the projected water demand is based on population growth trends reported by the San Joaquin Council of Governments, urban per capita water use consistent with projections in 2020 UWMPs, and urban area expansion from general plans or sphere of influence boundaries. An important assumption made in the projected water budget analysis is that due to projected urban growth, agricultural acreage is expected to decrease by approximately 22,000 acres. While there is agricultural growth anticipated in the eastern areas of the Subbasin and potential conversion of existing agricultural land to permanent irrigated crops, no reliable projections were available to include in the simulation; therefore, no additional agricultural land growth was added to the projected conditions scenario. An analysis of county agricultural reports can be performed to assess agricultural trends in future scenarios of the ESJWRM.

Average annual surface water inflows to the Eastern San Joaquin Subbasin’s stream system total an average of over

5.4 MAF/year in the projected conditions scenario. Under projected conditions, stream inflows of almost 4.5 MAF/year are augmented by stream gains from groundwater of 121,000 AF/year and runoff of precipitation to the stream system (656,000 AF/year) and return flow of applied water to the stream system (111,000 AF/year). Of these inflows, it is anticipated that 340,000 AF/year will be distributed to local growers to meet agricultural demand as surface water diversions and the remaining amount will leave the system in the form of San Joaquin River and Mokelumne River outflows (over 4.6 MAF/year), stream seepage (374,000 AF/year), and riparian intake from streams (37,000 AF/year).

Figure 2-115 summarizes the average projected inflows and outflows in the Eastern San Joaquin Subbasin stream system.

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Figure 2-115: Projected Average Annual Water Budget Estimates – Stream System The land surface water budget for the projected conditions scenario has annual average inflows and outflows of 2,342,000 AF/year. Inflows consist of precipitation (992,000 AF/year), surface water supply (525,000 AF/year), groundwater supply (799,000 AF/year), and riparian intake from streams (26,000 AF/year). The balance of this is the summation of average annual evapotranspiration (1,302,000 AF/year), runoff of precipitation to the stream system (656,000 AF/year), return flow of applied water to the stream system (111,000 AF/year), deep percolation (270,000 AF/year), and other flows due to land expansion and temporary storage in the root-zone and unsaturated (vadose) zones (4,000 AF/year). A summary of these flows can be seen below in Figure 2-116.

Figure 2-116: Projected Average Annual Water Budget Estimates – Land Surface System EXHIBIT 1
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Figure 2-117 below shows how anticipated expansion in surface water supplies is reflected by decreases to groundwater pumping (799,000 AF/year) relative to historical conditions estimates. Subsurface outflow to neighboring subbasins (57,000 AF/year) and stream gain from groundwater (110,000 AF/year) bring the total Subbasin discharges to 966,000 AF/year.

Under projected conditions, the groundwater system of the Eastern San Joaquin Subbasin experiences an average of 967,000 AF/year of inflows each year, of which 270,000 AF/year is deep percolation. There is also stream seepage (298,000 AF/year), as well as other recharge which includes recharge from canals, reservoirs, and MAR projects (165,00 AF/year), and subsurface inflows (204,000 AF/year) from the Sierra Nevada Mountains and the neighboring subbasins of Cosumnes, Modesto, South American, Solano, East Contra Costa, and Tracy.

The projected water budget has greater outflows than inflows, resulting in an average annual decline in groundwater storage of 30,000 AF/year. Figure 2-117 summarizes the average projected groundwater inflows and outflows in the Eastern San Joaquin Subbasin.

Figure 2-117: Projected Average Annual Water Budget Estimates – Groundwater System As seen previously in Table 2-17 for the historical calibration, Table 2-18 shows the projected conditions water demands, supplies, and change in groundwater storage averaged based on the San Joaquin Valley Water Year Hydrologic Classification or water year type. As expected, in wet years there is more precipitation and surface water to meet more of the water demand, reducing the need for groundwater pumping and increasing groundwater storage.

However, in dry years, more groundwater is pumped to meet the demand not met by surface water or precipitation, which leads to a decrease of groundwater storage. Unlike the historical calibration, the 55-year period allows for enough of each water year type to calculate meaningful averages, and the changes in supplies and demands are consistent with expectations for each water year type.

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Table 2-18: Average Annual Values for Key Components of Projected Water Budget by Year Type Water Year Type (San Joaquin River Index)
Component Wet Above
Normal
Below
Normal Dry Critical 55-Year
Number of Years1 19 7 3 10 16 55
Precipitation, AF/year
(Precipitation, inches)
1,402,000
(22.0)
987,000
(15.5)
895,000
(14.0)
772,000
(12.1)
662,000
(10.4)
992,000
(15.6)
Water Demand (AF/year)
Ag Demand 1,156,000 1,186,000 1,183,000 1,178,000 1,182,000 1,173,000 Urban Demand 138,000 137,000 137,000 142,000 145,000 140,000 Total Demand2 1,293,000 1,323,000 1,319,000 1,320,000 1,327,000 1,313,000 Water Supply (AF/year)
Total Surface Water
Supply 564,000 562,000 567,000 518,000 460,000 525,000
Agricultural 478,000 476,000 481,000 448,000 407,000 452,000 Urban and Industrial 86,000 86,000 86,000 70,000 53,000 73,000 Total Groundwater
Supply 736,000 769,000 761,000 817,000 883,000 799,000
Agricultural 685,000 719,000 709,000 740,000 787,000 732,000 Urban and Industrial 52,000 52,000 52,000 74,000 94,000 67,000 Total Supply (AF/year)2 1,300,000 1,331,000 1,328,000 1,335,000 1,343,000 1,324,000 Change in
Groundwater Storage
(AF/year)2
165,000 -24,000 -4,000 -125,000 -209,000 -30,000
Notes:
1 List of projected water budget water years by water year type:

Wet: 1969, 1974, 1975, 1978, 1980, 1982, 1983, 1986, 1993, 1995, 1996, 1997, 1998, 2005, 2006, 2011, 2017, 2019, 2023 Above Normal: 1970, 1973, 1979, 1984, 1999, 2000, 2010
Below Normal: 1971, 2003, 2018
Dry: 1972, 1981, 1985, 2001, 2002, 2004, 2009, 2012, 2016, 2020 Critical: 1976, 1977, 1987, 1988, 1989, 1990, 1991, 1992, 1994, 2007, 2008, 2013, 2014, 2015, 2021, 2022 2 Summations in table may not match the numbers in the table. This is due to the rounding of model results.

2.4.5.4 Projected Water Budget with Climate Change Estimates (ESJWRM PCBL-CC Version 3.0) The projected water budget with climate change is used to estimate future baseline conditions of supply, demand, and aquifer response to Plan implementation, with the additional effects of climate change on available water supply and increasing agricultural demand. The projected conditions scenario with climate change in the ESJWRM is used to evaluate the water budget assuming a 2040 level of development and using hydrology from water years 1969-2023, adjusted for climate change impacts.

Subsequent to completion and submittal of the GSP in January of 2020, refinements and enhancements were made during two major updates to the historical data for the updated historical ESJWRM, which in turn, required updates to the projected conditions baseline ESJWRM. As in all previous sections, ESJWRM Version 3.0 water budgets are included in the following section. This projected water budget with climate change updates and the associated results are documented in Appendix 2-C of this revised GSP.

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Average annual surface water inflows to the Eastern San Joaquin Subbasin’s stream system total an average of just under 6.0 MAF/year in the projected conditions with climate change scenario. Under projected conditions with climate change, stream inflows of 4.9 MAF/year are augmented by stream gains from groundwater of 115,000 AF/year and runoff of precipitation to the stream system (753,000 AF/year) and return flow of applied water to the stream system (112,000 AF/year). Of these inflows, it is anticipated that 340,000 AF/year will be distributed to local growers to meet agricultural demand as surface water diversions and the remaining amount will leave the system in the form of San Joaquin River and Mokelumne River outflows (5.1 MAF/year), stream seepage (420,000 AF/year), and riparian intake from streams (40,000 AF/year).

Figure 2-115 summarizes the average projected inflows and outflows in the Eastern San Joaquin Subbasin stream system.

Figure 2-118: Projected Average Annual Water Budget Estimates with Climate Change – Stream System
The land surface water budget for the projected conditions with climate change scenario has annual average inflows and outflows of 2,520,000 AF/year. Inflows consist of precipitation (1,087,000 AF/year), surface water supply (525,000 AF/year), groundwater supply (879,000 AF/year), and riparian intake from streams (29,000 AF/year). The balance of this is the summation of average annual evapotranspiration (1,384,000 AF/year), runoff of precipitation to the stream system (753,000 AF/year), return flow of applied water to the stream system (112,000 AF/year), deep percolation (268,000 AF/year), and other flows due to land expansion and temporary storage in the root-zone and unsaturated (vadose) zones (5,000 AF/year). A summary of these flows can be seen below in Figure 2-116.

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Figure 2-119: Projected Average Annual Water Budget Estimates with Climate Change – Land Surface System
Figure 2-120 below shows how effects due to climate change are reflected by increases to groundwater pumping (879,000 AF/year) relative to the project conditions scenario. Subsurface outflow to neighboring subbasins (111,000 AF/year) and stream gain from groundwater (53,000 AF/year) bring the total Subbasin discharges to 1,043,000 AF/year.

Under projected conditions with climate change, the groundwater system of the Eastern San Joaquin Subbasin experiences an average of 1,044,000 AF/year of inflows each year, of which 268,000 AF/year is deep percolation.

There is also stream seepage (330,000 AF/year), as well as other recharge which includes recharge from canals, reservoirs, and MAR projects (168,00 AF/year), and subsurface inflows (222,000 AF/year) from the Sierra Nevada Mountains and the neighboring subbasins of Cosumnes, Modesto, South American, Solano, East Contra Costa, and Tracy.

The projected water budget has greater outflows than inflows, resulting in an average annual decline in groundwater storage of 56,000 AF/year. Figure 2-120 summarizes the average projected groundwater inflows and outflows in the Eastern San Joaquin Subbasin.

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Figure 2-120: Projected Average Annual Water Budget Estimates with Climate Change – Groundwater System
Table 2-19 shows the projected conditions with climate change’s water demands, supplies, and change in groundwater storage averaged based on the San Joaquin Valley Water Year Hydrologic Classification or water year type. As expected, in wet years there is more precipitation and surface water to meet more of the water demand, reducing the need for groundwater pumping and increasing groundwater storage. However, in dry years, more groundwater is pumped to meet the demand not met by surface water or precipitation, which leads to a decrease of groundwater storage.

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Table 2-19: Average Annual Values for Key Components of Projected Conditions with Climate Change Water Budget by Year Type
Water Year Type (San Joaquin River Index)
Component Wet Above
Normal
Below
Normal Dry Critical 55-Year
Number of Years1 19 7 3 10 16 55
Precipitation, AF/year
(Precipitation, inches)
1,547,000
(24.3)
1,124,000
(17.6)
952,000
(14.9)
829,000
(13.0)
712,000
(11.2)
1,087,000
(17.1)
Water Demand (AF/year)
Ag Demand 1,238,000 1,261,000 1,262,000 1,258,000 1,263,000 1,253,000 Urban Demand 138,000 137,000 136,000 142,000 145,000 139,000 Total Demand2 1,376,000 1,398,000 1,398,000 1,400,000 1,408,000 1,392,000 Water Supply (AF/year)
Total Surface Water
Supply 564,000 562,000 566,000 518,000 459,000 525,000
Agricultural 478,000 476,000 481,000 448,000 407,000 452,000 Urban and Industrial 86,000 86,000 85,000 69,000 53,000 73,000 Total Groundwater
Supply 818,000 844,000 841,000 897,000 964,000 879,000
Agricultural 768,000 795,000 790,000 821,000 869,000 812,000 Urban and Industrial 52,000 52,000 52,000 74,000 94,000 68,000 Total Supply (AF/year)2 1,382,000 1,406,000 1,407,000 1,415,000 1,423,000 1,404,000 Change in
Groundwater Storage
(AF/year)2
139,000 -55,000 -39,000 -150,000 -233,000 -56,000
Notes:
1 List of projected water budget water years by water year type:

Wet: 1969, 1974, 1975, 1978, 1980, 1982, 1983, 1986, 1993, 1995, 1996, 1997, 1998, 2005, 2006, 2011, 2017, 2019, 2023 Above Normal: 1970, 1973, 1979, 1984, 1999, 2000, 2010
Below Normal: 1971, 2003, 2018
Dry: 1972, 1981, 1985, 2001, 2002, 2004, 2009, 2012, 2016, 2020 Critical: 1976, 1977, 1987, 1988, 1989, 1990, 1991, 1992, 1994, 2007, 2008, 2013, 2014, 2015, 2021, 2022 2 Summations in table may not match the numbers in the table. This is due to the rounding of model results.

2.4.6 Projected Water Budget with Demand Reduction Estimates (ESJWRM PCBL-DR Version

3.0)
Sustainable yield is defined for SGMA purposes as “the maximum quantity of water, calculated over a base period representative of long-term conditions in the basin and including any temporary surplus, that can be withdrawn annually from a groundwater supply without causing an undesirable result.” (CWC §10721(w)). Groundwater pumping under sustainable conditions for the Eastern San Joaquin Subbasin was calculated through development of an ESJWRM sustainable conditions scenario in which the goal was to generate a long-term (55-year) change in Subbasin groundwater storage of zero, a conservative approach, as a change in storage of greater than zero could occur without causing undesirable results. From 2040, the 55 years of long-term hydrology was applied and various scenarios were run to see what level of groundwater production resulted in a long-term change in storage of, or very close to, zero.

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The sustainable conditions scenario is based on the projected conditions scenario (see Section 2.4.4.3 and Figure 2-117) modified by lowering groundwater production across the model domain.

In practice, Subbasin overdraft could be addressed through reduced groundwater production, increased recharge, or a combination of the two; focusing on groundwater production is just for simulation purposes to calculate the Subbasin production under sustainable conditions. The sustainable conditions scenario estimates future conditions of supply, demand, and the resulting aquifer response to implementation of sustainable conditions in the Subbasin. Under sustainable conditions, groundwater pumping activities in the Subbasin are not anticipated to create changes in groundwater inflow that could impact GSP implementation in neighboring subbasins.

There are uncertainties associated with projections in the ESJWRM scenarios due to the sequence of the hydrologic period, population projections, future cropping patterns, and irrigation practices and technologies, as well as uncertainties inherent in the representation of the physical groundwater and surface water system by the model.

Therefore, to account for these uncertainties, a range of assumptions (from high-end estimates to low-end estimates) are used in running model scenarios to estimate the production under sustainable conditions and an initial estimate of the adjustment that would be required to achieve the production under sustainable conditions over the 55-year planning period. These assumptions will be honed over time in updates to this Plan and refinements to the ESJWRM as described in Section 7.4.1.

The results of the Subbasin ESJWRM Projected Condition BaseLine with Demand Reduction (PCBL-DR) are summarized below. Detailed assumptions and results for the PCBL-DR are included in Appendix 2-C of this updated GSP. As with the PCBL, the projected conditions with demand reduction scenario of the ESJWRM assumes a 2040 level of development and hydrology from water years 1969-2023.

2.4.6.1 Land and Water Use Water Budget
The land and water use budget includes two different versions, agricultural and urban, and represents the balance of the model-calculated water demands with the water supplied. Both the agricultural and urban versions include the same components that make up the water balance:
• Inflows:
o Groundwater pumping
o Surface water deliveries
o Shortage (if applicable)
• Outflows:
o Demand (either agricultural or urban)
o Surplus (if applicable)
The average annual PCBL-DR Version 3.0 water demand for the Subbasin within the 55-year simulation period is 1,199 thousand acre-feet per year (TAFY), consisting of approximately 1,059 TAFY of agricultural demand and 140 TAFY of urban demand. This demand is met by an annual average of 526 TAFY of surface water deliveries (452 TAFY of agricultural and 73 TAFY of urban deliveries) and is supplemented by 693 TAFY of groundwater production (628 TAFY of agricultural and 65 TAFY of urban pumping). Due to uncertainties in the estimation of projected agricultural demand and historical supply records, there is 21 TAFY of surplus in the Subbasin-scale agricultural water supply, which is insignificant relative to the total volume of water use. Shortage and surplus represent a misalignment between the reported, estimated, or assumed water supply (groundwater pumping and surface water deliveries) and the calculated demands. In the projected conditions, there are uncertainties in the assumptions and parameters used for both monthly supply and demand estimates and/or calculations, resulting in misalignments, which is reported as shortage or surplus. These annual averages are shown in Table 2-20. The annual land and water use budgets across EXHIBIT 1
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the ESJ Subbasin are shown in Figure 2-121 and Figure 2-122 for the Subbasin as a whole, showing the agricultural and urban, respectively, demands plotted with water supplies.

Table 2-20 also includes the PCBL Version 3.0 results and a demand reduction benefit calculated as the PCBL-DR Version 3.0 results minus the PCBL Version 3.0 results. For urban areas, the 15% reduction in urban demand that was applied to the PCBL-DR Version 3.0 across all major agencies in the Subbasin is reflected in the reduction in urban demand of 16 TAFY compared to the PCBL Version 3.0. For agricultural areas, the PCBL-DR Version 3.0 has 26 thousand acres less of agricultural area, which results in 95 TAFY reduction in agricultural demand compared the PCBL Version 3.0. This represents a comparable reduction in agricultural groundwater pumping of 93 TAFY.

Table 2-20: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL Version 3.0 and PCBL-DR Version 3.0
Annual Average
Land and Water Use Budget Component PCBL Version

3.0 PCBL-DR
Version 3.0
DR Benefit
(PCBL-DR
Version 3.0
minus PCBL
Version 3.0)
Agricultural Area (thousand acres) 365 340 -26
Agricultural Demand (TAFY) 1,153 1,059 -95
Agricultural Groundwater Pumping (TAFY) 721 628 -93
Agricultural Surface Water Deliveries (TAFY) 452 452 0
Agricultural Surplus (TAFY)
1 19 21 2
Urban Area (thousand acres) 129 129 0
Urban Demand (TAFY) 156 140 -16
Urban Groundwater Pumping (TAFY) 67 64 -3
Urban Surface Water Deliveries (TAFY) 73 73 0
Urban Shortage (TAFY)
1 16 2 -14
1 Shortage and surplus represent a misalignment between the reported, estimated or assumed water supply (groundwater pumping and surface water deliveries) and the calculated demands. In the historical model, this can occur when there are inaccuracies in the reported water supplies or uncertainties in the methodology and/or parameters used to calculate the demand. In the projected conditions, there are uncertainties in the assumptions and parameters used for both monthly supply and demand estimates and/or calculations, resulting in misalignments, which is reported as shortage or surplus.

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Figure 2-121: ESJ Subbasin Projected Agricultural Demand in the PCBL-DR Version 3.0 Figure 2-122: ESJ Subbasin Projected Urban Demand in the PCBL-DR Version 3.0 EXHIBIT 1
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2.4.6.2 Hydrologic Groundwater Water Budget
The primary components of the groundwater budget are the same as represented in the historical model.

Corresponding to the major hydrologic processes affecting groundwater flow in the Subbasin, these are:
• Inflows:
o Deep percolation (from rainfall and irrigation applied water) o Gain from stream (or recharge due to stream seepage)
o Boundary inflow (from surrounding groundwater subbasins and the Sierra Nevada Mountains) o Other Recharge (from other sources such as irrigation canal seepage, managed aquifer recharge projects, and reservoir seepage)
• Outflows:
o Groundwater pumping
o Loss to stream (or outflow to streams and rivers)
o Boundary outflow (to surrounding groundwater subbasins) o Change in groundwater storage (can be either an inflow or outflow) Pumping in the PCBL-DR Version 3.0 remains the largest component in the groundwater budget with an annual average 704 TAFY. The PCBL-DR Version 3.0 offsets this pumping with 247 TAFY of deep percolation, a net gain from stream of 211 TAFY, 165 TAFY of other recharge, and a total subsurface inflow of 81 TAFY. The cumulative change in groundwater storage can be calculated from the average annual change in groundwater storage. Due to inherent uncertainties in model input data, calculations, and calibration, all budget components have a degree of uncertainty. Given this uncertainty, the projected long-term average annual the groundwater storage deficit in ESJ Subbasin in the PCBL-DR Version 3.0 is -200 AFY, with the negative sign actually indicating an absence of groundwater overdraft and an increase in storage over the 55 years of the PCBL-DR Version 3.0. These annual averages are shown in Table 2-21. The groundwater budget, with cumulative change in storage, is shown for the ESJ Subbasin in Figure 2-123.

Table 2-21 also includes the PCBL Version 3.0 results and a demand reduction benefit calculated as PCBL-DR Version

3.0 results minus the PCBL Version 3.0 results. The simulated results indicate that the demand reduction may resolve the PCBL Version 3.0 Subbasin overdraft condition when impacts due to climate change are not included. Without the demand reduction, the modeling shows an average overdraft of 30 TAFY over the 55 years of the PCBL Version 3.0 simulation. With the demand reduction in place, the modeling shows approximately 0 TAFY in projected overdraft on average in the PCBL-DR Version 3.0. The PCBL-DR Version 3.0 shows an average increase of 30 TAFY of groundwater in storage when compared to the PCBL.

Compared to PCBL Version 3.0, the PCBL-DR Version 3.0 has 95 TAFY less groundwater pumping due to the percentage reduction in urban per capita water use and agricultural areas, and 29 TAFY less stream seepage into the groundwater system due to higher groundwater levels. Other hydrologic groundwater budget component differences are small between the PCBL Version 3.0 and PCBL-DR Version 3.0.

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Table 2-21: ESJ Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between PCBL Version 3.0 and PCBL-DR Version 3.0
Annual Average
Hydrologic Groundwater Budget
Component PCBL
Version 3.0

PCBL-DR
Version 3.0
DR Benefit
(PCBL-DR
Version 3.0
minus PCBL
Version 3.0)
Deep Percolation (TAF) 270 247 -23
Other Recharge (TAF) 165 165 0
Net Stream Seepage (TAF) 240 211 -29
Net Boundary Inflow (TAF) 94 81 -13
Groundwater Pumping (TAF) 799 704 -95
Change in Groundwater Storage (TAF) -30 0 30
Figure 2-123: ESJ Subbasin Projected Hydrologic Groundwater Budget in PCBL-DR Version 3.0 The sustainable conditions scenario results in groundwater outflows almost equal to groundwater inflows, bringing the long-term (55-year) average change in groundwater storage to close to zero. Based on this analysis, to achieve a simulated long-term average change in storage of 0 AFY, the Subbasin-wide pumping would be approximately is 704,000 AF/year ± 10 percent. This assumes that hydrology and surface water conditions continue as modeled and no projects are implemented.

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In order to achieve a net-zero change in groundwater storage over a 55-year planning period, approximately 95,000 AF/year of direct or in lieu groundwater recharge and/or reduction in agricultural and urban groundwater pumping would need to be implemented in the Eastern San Joaquin Subbasin to reduce the projected groundwater pumping to the sustainable conditions level, without consideration to impacts of climate change. This number (95,000 AF/year) is larger than the estimated annual overdraft of the projected conditions scenario (30,000 AF/year) due to the integrated nature of a groundwater subbasin. As efforts are made to reach sustainability in a subbasin, flows to and from neighboring basins and flows to and from streams may vary due to proposed management actions resulting in increased groundwater levels, creating the need for additional recharge or pumping reduction greater than the overdrafted amount.

2.4.7 Projected Water Budget with Climate Change and Demand Reduction Estimates (ESJWRM PCBL-CC-DR Version 3.0)

2.4.7.1 Land and Water Use Water Budget
To assess the impact of climate change on the sustainable conditions run, climate change impacts, described in Section

2.4.4.4, were incorporated into the PCBL-DR scenario.

The average annual PCBL-CC-DR Version 3.0 water demand for the Subbasin within the 55-year simulation period is 1,214 TAFY, consisting of approximately 1,074 TAFY of agricultural demand and 140 TAFY of urban demand. This demand is met by an annual average of 526 TAFY of surface water deliveries (453 TAFY of agricultural and 73 TAFY of urban deliveries) and is supplemented by 702 TAFY of groundwater production (637 TAFY of agricultural and 65 TAFY of urban pumping). Due to uncertainties in the estimation of projected agricultural demand and historical supply records, there is about 16 TAFY of surplus in the Subbasin scale agricultural water use budget, which is insignificant relative to the total volume of water use. Shortage and surplus represent a misalignment between the reported, estimated, or assumed water supply (groundwater pumping and surface water deliveries) and the calculated demands.

In the projected conditions, there are uncertainties in the assumptions and parameters used for both monthly supply and demand estimates and/or calculations, resulting in misalignments, which is reported as shortage or surplus. These annual averages are shown in Table 2-22. The annual land and water use budgets across the ESJ Subbasin are shown in Figure 2-124 and Figure 2-125 for the Subbasin as a whole, showing the agricultural and urban, respectively, demands plotted with water supplies.

Table 2-22 also includes the PCBL-CC Version 3.0 results and a demand reduction benefit calculated as PCBL-CCDR Version 3.0 results minus PCBL-CC Version 3.0 results. For urban areas, the 15% reduction in urban demand that applied to the PCBL-CC-DR Version 3.0 across all major agencies in the Subbasin is reflected in the reduction in urban demand of 17 TAFY compared to the PCBL-CC Version 3.0. For agricultural areas, the PCBL-CC-DR Version 3.0 has 44 thousand acres less agricultural area, which results in 166 TAFY less agricultural demand compared to the PCBLCC. This represents a comparable reduction in agricultural groundwater pumping of 164 TAFY.

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Table 2-22: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBLCC Version 3.0 and PCBL-CC-DR Version 3.0 Annual Average
Land and Water Use Budget Component PCBL-CC
Version 3.0

PCBL-CC-DR
Version 3.0
DR Benefit
(PCBL-CC-DR
Version 3.0
minus PCBLCC Version 3.0)
Agricultural Area (thousand acres) 365 321 -44
Agricultural Demand (TAF) 1,240 1,074 -166
Agricultural Groundwater Pumping (TAF) 801 637 -164
Agricultural Surface Water Deliveries (TAF) 452 453 1
Agricultural Surplus (TAF)1
14 16 2
Urban Area (thousand acres) 129 129 0
Urban Demand (TAF) 156 140 -16
Urban Groundwater Pumping (TAF) 67 65 -3
Urban Surface Water Deliveries (TAF) 73 73 0
Urban Shortage (TAF)1
16 2 -14
1 Shortage and surplus represent a misalignment between the reported, estimated or assumed water supply (groundwater pumping and surface water deliveries) and the calculated demands. In the historical model, this can occur when there are inaccuracies in the reported water supplies or uncertainties in the methodology and/or parameters used to calculate the demand. In the projected conditions, there are uncertainties in the assumptions and parameters used for both monthly supply and demand estimates and/or calculations, resulting in misalignments, which is reported as shortage or surplus.

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Figure 2-124: ESJ Subbasin Projected Agricultural Demand in the PCBL-CC-DR Version 3.0 EXHIBIT 1
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Figure 2-125: ESJ Subbasin Projected Urban Demand in the PCBL-CC-DR Version 3.0

2.4.7.2 Hydrologic Groundwater Water Budget
Pumping in the PCBL-CC-DR Version 3.0 remains the largest component in the groundwater budget with an annual average 713,200 AFY. The PCBL-CC-DR Version 3.0 offsets this pumping with 233,600 AFY of deep percolation, a net gain from stream of 223,200, 167,700 AFY of other recharge, and a total subsurface inflow of 88,600 AFY annually.

The cumulative change in groundwater storage can be calculated from the annual change in groundwater storage. Due to inherent uncertainties in model input data, calculations, and calibration, all budget components have a degree of uncertainty. Even with this uncertainty, the projected long-term average annual the groundwater storage deficit in ESJ Subbasin in the PCBL-CC-DR Version 3.0 is 0 AFY. These annual averages are shown in Table 2-23. The groundwater budgets, with average cumulative change in storage, are shown for the ESJ Subbasin in Figure 2-126.

Table 2-23 also includes the PCBL-CC results and a demand reduction benefit calculated as the PCBL-CC-DR Version

3.0 results minus the PCBL-CC results. The results indicate that the demand reduction will resolve the PCBL-CC Subbasin overdraft condition when impacts due to climate change are included. Without the demand reduction, the modeling shows an average overdraft of 56,200 AFY over the 55 years of the PCBL-CC simulation. With the demand reduction in place, the modelling shows a projected overdraft of 0 AFY on average in the PCBL-CC-DR Version 3.0.

The PCBL-CC-DR Version 3.0 shows an average increase of 56,200 AFY of groundwater in storage when compared to the PCBL-CC.

Compared to the PCBL-CC, with the demand reduction modeled, the PCBL-CC-DR Version 3.0 has 166,200 AFY less groundwater pumping due to the percentage reduction in urban per capita water use and agricultural areas, and 53,000 AFY less stream seepage into the groundwater system due to higher groundwater levels. Other hydrologic groundwater budget component differences are small between the PCBL-CC and PCBL-CC-DR Version 3.0 simulations.

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Table 2-23: ESJ Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between the PCBL-CC and the PCBL-CC-DR Version 3.0
Annual Average
Hydrologic Groundwater Budget
Component

PCBL-CC PCBL-CC-DR
Version 3.0
DR Benefit
(PCBL-CC-DR
Version 3.0
minus PCBLCC)
Deep Percolation (AF) 268,000 233,600 -34,400
Other Recharge (AF) 168,100 167,700 -400
Net Stream Seepage (AF) 276,200 223,200 -53,000
Net Boundary Inflow (AF) 110,900 88,600 -22,300
Groundwater Pumping (AF) 879,400 713,200 -166,200
Change in Groundwater Storage (AF) -56,200 0 56,200
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Figure 2-126: ESJ Subbasin Projected Hydrologic Groundwater Budget in the PCBL-CC-DR Version

3.0 The sustainable conditions scenario with climate change results in groundwater outflows almost equal to groundwater inflows, bringing the long-term (55-year) average change in groundwater storage to close to zero. Based on this analysis, to achieve a simulated long-term average change in storage of 0 AFY, the Subbasin-wide pumping would be approximately is 713,000 AF/year ± 10 percent. This assumes that hydrology and surface water conditions continue as modeled and no projects are implemented.

In order to achieve a net-zero change in groundwater storage over a 55-year planning period, approximately 166,000 AF/year of direct or in lieu groundwater recharge and/or reduction in agricultural and urban groundwater pumping would need to be implemented in the Eastern San Joaquin Subbasin to reduce the projected groundwater pumping to the sustainable conditions level, considering the of impacts of climate change.

2.4.8 Projected Water Budget with PMAs Estimates (ESJWRM PCBL-PMA Version 3.0) The results of the Subbasin ESJWRM Projected Condition BaseLine with Category A Projects and Management Actions (PCBL-PMA) are summarized below. Detailed results for the PCBL-PMA are included in Appendix 2-C of this updated GSP. As with the PCBL, the projected conditions with projects and management actions scenario of the ESJWRM assumes a 2040 level of development and hydrology from water years 1969-2023. A summary of the 12 Category A PMAs simulated as additional diversions in the PCBL-PMA model is provided in Table 2-24. along with fractions for recoverable loss (i.e., percolation or canal seepage), non-recoverable loss (i.e., evaporation), and delivery (i.e., amount delivered is equal to the total amount minus the recoverable and non-recoverable losses). One PMA was EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 2-201
Basin Setting November 2024
already included in the PCBL as Diversion 55 and is also included in Table 2-24. The remaining 65 PCBL diversions are summarized in the projected documentation (Appendix 2-C).

City of Stockton’s Advanced Metering Infrastructure project was added as a Category A project during the public comment period of the 2024 GSP Amendment. Therefore, it is not included in the PMA simulation results shown in the 2024 GSP Amendment. It will be simulated in future iterations of ESJWRM PCBL-PMA. Appendix 2-C details documentation on only the 12 Category A PMAs that were simulated as part of the 2024 GSP Amendment.

2.4.8.1 Land and Water Use Water Budget
The land and water use budget includes two different versions, agricultural and urban, and represents the balance of the model-calculated water demands with the water supplied. Both the agricultural and urban versions include the same components that make up the water balance:
• Inflows:
o Groundwater pumping
o Surface water deliveries
o Shortage (if applicable)
• Outflows:
o Demand (either agricultural or urban)
o Surplus (if applicable)
The average annual PCBL-PMA Version 3.0 water demand for the Subbasin within the 55-year simulation period is 1,315 TAFY, consisting of approximately 1,153 TAFY of agricultural demand and 162 TAFY of urban demand. This demand is met by an annual average of 572 TAFY of surface water deliveries (493 TAFY of agricultural and 79 TAFY of urban deliveries) and is supplemented by 755 TAFY of groundwater production (687 TAFY of agricultural and 68 TAFY of urban pumping). Due to uncertainties in the estimation of projected agricultural demand and historical supply records, there is 28 TAFY of surplus in the Subbasin-scale agricultural water supply, which is insignificant relative to the total volume of water use. Shortage and surplus represent a misalignment between the reported, estimated, or assumed water supply (groundwater pumping and surface water deliveries) and the calculated demands. In the projected conditions, there are uncertainties in the assumptions and parameters used for both monthly supply and demand estimates and/or calculations, resulting in misalignments, which is reported as shortage or surplus. These annual averages are shown in Table 2-25
Table 2-25 also includes the PCBL Version 3.0 results and a Category A projects benefit calculated as the PCBL-PMA Version 3.0 results minus the PCBL Version 3.0 results. The PCBL-PMA Version 3.0 has an average of 41 TAFY more surface water for agricultural purposes and 6 TAFY more surface water for urban areas compared to the PCBL Version

3.0. For urban areas, this represents a reduction in groundwater pumping of 600 AFY. For agricultural areas, the increased surface water results in 34 TAFY less groundwater pumping, a number smaller than the amount of surface water provided due to a mismatch between the Category A water supplied and model-calculated agricultural demand on a monthly basis.

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Table 2-24: Summary of ESJWRM Category A Projects Surface Water Deliveries ID Description Diversion Delivery Area Primary Fraction Average Annual Location Use
RL* NL** Delivery
Diversion***
(acre- feet)
55 OID In-lieu and Direct
Recharge Project
Import (outside
of ESJWRM)
Landowners outside of OID’s
eastern boundary Ag 0% 0% 100% 3,000
67 Stockton East WD Lake
Grupe In-Lieu Recharge Calaveras River
Approximately 1,750 acres
of orchards surrounding
Lake Grupe in SEWD
Ag 0% 0% 100% 4,300
68 Stockton East WD Surface
Water Implementation
Expansion
Import (outside
of ESJWRM)
Approximately 6,750 acres
adjacent to surface water
conveyance systems in
SEWD
Ag 0% 0% 100% 13,300
69 Stockton East WD West
Groundwater Recharge Basin
Import (outside
of ESJWRM)
Recharge basin near SEWD
water treatment plant Recharge 100% 0% 0% 10,200
70 Central San Joaquin WCD
Capital improvement Program
Import (outside
of ESJWRM) CSJWCD Ag 15% 2% 83% 20,500
71 Long-term Water Transfer to
Stockton East WD for M&I
Import (outside
of ESJWRM)
City of Stockton area urban
users
Urban 0% 0% 100% 12,200
72 City of Lodi White Slough
Water Pollution Control
Facility Expansion
Import (outside
of ESJWRM)
890 acres of agricultural land
surrounding White Slough
Pollution Control Facility
Ag 4% 2% 94% 3,700
73 North San Joaquin WCD
South System Modernization
Mokelumne
River NSJWCD South System Ag 0% 0% 100% 6,900
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ID Description Diversion Delivery Area Primary Fraction Average Annual Location Use
RL* NL** Delivery
Diversion***
(acre- feet)
74 North San Joaquin WCD
Tecklenburg Recharge
Project
Mokelumne
River
Recharge basin located in
NSJWCD South System Recharge 100% 0% 0% 1,300
75 North San Joaquin WCD
South System Groundwater
Banking
with EBMUD
Mokelumne
River NSJWCD South System Ag 0% 0% 100% 2,800
76 North San Joaquin WCD
North System
Modernization/Lasko
Recharge
Mokelumne
River NSJWCD North System Ag 50% 0% 50% 4,000
77 City of Stockton Delta Water
Treatment Plant Groundwater
Recharge Improvements
Project Geotechnical
Investigation
Import (outside
of ESJWRM)
Recharge basin adjacent to
Delta Water Treatment Plant Recharge 100% 0% 0% 5,000
82 North San Joaquin WCD
Private Pump Partnerships
Mokelumne
River
Riparian areas along
Mokelumne River within
NSJWCD
Recharge 50% 0% 50% 3,000
*RL = Recoverable Loss (canal seepage or recharge)
**NL = Non-Recoverable Loss (evaporation)
*** Averages calculated only for years with diversions occurring (i.e., non-zero average) EXHIBIT 1
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Table 2-25: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL Version 3.0 and PCBL-PMA Version 3.0
Annual Average
Land and Water Use Budget Component PCBL Version

3.0 PCBL-PMA
Version 3.0
PMA Benefit
(PCBL-PMA
Version 3.0
minus PCBL
Version 3.0)
Agricultural Area (thousand acres) 365 365 0
Agricultural Demand (TAFY) 1,153 1,153 0
Agricultural Groundwater Pumping (TAFY) 721 687 -34
Agricultural Surface Water Deliveries (TAFY) 452 493 41 Agricultural Surplus (TAFY)
1 19 28 8
Urban Area (thousand acres) 129 129 0
Urban Demand (TAFY) 156 162 6
Urban Groundwater Pumping (TAFY) 67 68 1
Urban Surface Water Deliveries (TAFY) 73 79 6
Urban Shortage (TAFY)
1 16 16 0
1 Shortage and surplus represent a misalignment between the reported, estimated or assumed water supply (groundwater pumping and surface water deliveries) and the calculated demands. In the historical model, this can occur when there are inaccuracies in the reported water supplies or uncertainties in the methodology and/or parameters used to calculate the demand. In the projected conditions, there are uncertainties in the assumptions and parameters used for both monthly supply and demand estimates and/or calculations, resulting in misalignments, which is reported as shortage or surplus.

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Figure 2-127: ESJ Subbasin Projected Agricultural Demand in the PCBL-PMA Figure 2-128: ESJ Subbasin Projected Urban Demand in the PCBL-PMA EXHIBIT 1
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2.4.8.2 Hydrologic Groundwater Budget
The primary components of the groundwater budget are the same as represented in the historical model.

Corresponding to the major hydrologic processes affecting groundwater flow in the Subbasin, these are:
• Inflows:
o Deep percolation (from rainfall and irrigation applied water) o Gain from stream (or recharge due to stream seepage)
o Boundary inflow (from surrounding groundwater subbasins and the Sierra Nevada Mountains) o Other Recharge (from other sources such as irrigation canal seepage, managed aquifer recharge projects, and reservoir seepage)
• Outflows:
o Groundwater pumping
o Loss to stream (or outflow to streams and rivers)
o Boundary outflow (to surrounding groundwater subbasins) o Change in groundwater storage (can be either an inflow or outflow) Pumping in the PCBL-PMA Version 3.0 remains the largest component in the groundwater budget with an annual average 766 TAFY. The PCBL-PMA Version 3.0 offsets this pumping with 275 TAFY of deep percolation, a net gain from stream of 223 TAFY, 184 TAFY of other recharge, and a total subsurface inflow of 75 TAFY. The cumulative change in groundwater storage can be calculated from the annual change in groundwater storage. Due to inherent uncertainties in model input data, calculations, and calibration, all budget components have a degree of uncertainty.

Given this uncertainty, the projected long-term average annual the groundwater storage deficit in ESJ Subbasin in the PCBL-PMA Version 3.0 is 9 TAFY, indicating that some groundwater overdraft is still occurring even with the Category A projects. These annual averages are shown in Table 2-26. The groundwater budgets, with average cumulative change in storage, are shown for the ESJ Subbasin in Figure 2-129.

Table 2-26 also includes the PCBL Version 3.0 results and a Category A projects benefit calculated as the PCBL-PMA Version 3.0 results minus the PCBL Version 3.0 results. The results indicate that the Category A projects will resolve the PCBL Version 3.0 Subbasin overdraft condition when impacts due to climate change are not included. Without projects, the modeling shows an average overdraft of 30 TAFY over the 55 years of the PCBL Version 3.0 simulation.

With Category A projects in place, the modelling shows a projected overdraft of -9 TAFY on average in the PCBL-PMA Version 3.0. The PCBL-PMA Version 3.0 shows an average increase of 21 TAFY of groundwater in storage when compared to the PCBL Version 3.0. Compared to the PCBL Version 3.0, with Category A projects modeled, the PCBLPMA Version 3.0 has 33 TAFY less groundwater pumping due to the new in-lieu recharge projects, 19 TAFY more recharge (both direct recharge projects and canal seepage losses for the in-lieu recharge projects), and 17 TAFY less stream seepage into the groundwater system due to higher groundwater levels. Other hydrologic groundwater budget component differences are small between the PCBL Version 3.0 and PCBL-PMA Version 3.0 simulations.

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Table 2-26: ESJ Hydrologic Groundwater Budget Annual Average Comparison Between the PCBL (Version 3.0) and the PCBL-PMA (Version 3.0)
Annual Average
Hydrologic Groundwater Budget
Component PCBL
Version 3.0

PCBL-PMA
Version 3.0
PMA Benefit
(PCBL-PMA
Version 3.0
minus PCBL
Version 3.0)
Deep Percolation (TAF) 270 275 6
Other Recharge (TAF) 165 184 19
Net Stream Seepage (TAF) 240 223 -17
Net Boundary Inflow (TAF) 94 75 -19
Groundwater Pumping (TAF) 799 766 -33
Change in Groundwater Storage (AF) -30 -9 21
Figure 2-129: ESJ Subbasin Projected Hydrologic Groundwater Budget in the PCBL-PMA Version

3.0 EXHIBIT 1
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Basin Setting November 2024

2.4.9 Projected Water Budget with Climate Change and PMAs Estimates (ESJWRM PCBL-CCPMA Version 3.0) The results of the Subbasin ESJWRM Projected Condition BaseLine with Climate Change and Category A Projects and Management Actions (PCBL-CC-PMA) are summarized below. Detailed results for the PCBL-CC- PMA are included in Appendix 2-C of this revised GSP. As with the PCBL-CC, the projected conditions with climate change and projects and management actions scenario of the ESJWRM assumes a 2040 level of development and hydrology from water years 1969-2023 with the 2070 Central Tendency climate change dataset. A summary of the 13 Category A PMAs simulated as additional diversions in the PCBL-CC- PMA model is provided in Table 2-24, along with fractions for recoverable loss (i.e., percolation or canal seepage), non-recoverable loss (i.e., evaporation), and delivery (i.e., amount delivered is equal to the total amount minus the recoverable and non-recoverable losses).

2.4.9.1 Land and Water Use Water Budget
The average annual PCBL-CC-PMA Version 3.0 water demand for the Subbasin within the 55-year simulation period is 1,401 TAFY, consisting of approximately 1,238 TAFY of agricultural demand and 162 TAFY of urban demand. This demand is met by an annual average of 572 TAFY of surface water deliveries (493 TAFY of agricultural and 79 TAFY of urban deliveries) and is supplemented by 835 TAFY of groundwater production (767 TAFY of agricultural and 68 TAFY of urban pumping). Due to uncertainties in the estimation of projected agricultural demand and historical supply records, there is about 22 TAFY of surplus in the Subbasin scale agricultural water use budget, which is insignificant relative to the total volume of water use. Shortage and surplus represent a misalignment between the reported, estimated, or assumed water supply (groundwater pumping and surface water deliveries) and the calculated demands.

In the projected conditions, there are uncertainties in the assumptions and parameters used for both monthly supply and demand estimates and/or calculations, resulting in misalignments, which is reported as shortage or surplus. These annual averages are shown in Table 2-27. The annual land and water use budgets across the ESJ Subbasin are shown in
EXHIBIT 1
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Figure 2-130 and Figure 2-131 for the Subbasin as a whole, showing the agricultural and urban, respectively, demands plotted with water supplies.

Table 2-27 also includes the PCBL-CC Version 3.0 results and a Category A projects benefit calculated as the PCBLCC-PMA Version 3.0 results minus the PCBL-CC Version 3.0 results. The PCBL-CC-PMA Version 3.0 has an average of 41 TAFY more surface water for agricultural purposes and 6 TAFY more surface water for urban areas compared to the PCBL-CC Version 3.0. For urban areas, this represents a reduction in groundwater pumping of 600 AFY. For agricultural areas, the increased surface water results in 34 TAFY less groundwater pumping, a number smaller than the amount of surface water provided due to a mismatch between the Category A water supplied and model-calculated agricultural demand on a monthly basis.

Differences between the amount of surface water supplied for PCBL-PMA Version 3.0 and PCBL-CC-PMA Version 3.0 are due to differences in the amount of surface water available in streams impacted by climate change. These differences are small (less than 200 AFY) between results in Table 2-25 and Table 2-27.

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Table 2-27: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBLCC Version 3.0 and PCBL-CC-PMA Version 3.0 Annual Average
Land and Water Use Budget Component PCBL-CC
Version 3.0

PCBL-CC-PMA
Version 3.0
PMA Benefit
(PCBL-CC-PMA
Version 3.0
minus PCBLCC Version 3.0)
Agricultural Area (thousand acres) 365 365 0
Agricultural Demand (TAF) 1,240 1,238 -1
Agricultural Groundwater Pumping (TAF) 801 767 -34
Agricultural Surface Water Deliveries (TAF) 452 493 41
Agricultural Surplus (TAF)1 14 22 8
Urban Area (thousand acres) 129 129 0
Urban Demand (TAF) 156 162 6
Urban Groundwater Pumping (TAF) 67 68 1
Urban Surface Water Deliveries (TAF) 73 79 6
Urban Shortage (TAF)1 16 16 0
1 Shortage and surplus represent a misalignment between the reported, estimated or assumed water supply (groundwater pumping and surface water deliveries) and the calculated demands. In the historical model, this can occur when there are inaccuracies in the reported water supplies or uncertainties in the methodology and/or parameters used to calculate the demand. In the projected conditions, there are uncertainties in the assumptions and parameters used for both monthly supply and demand estimates and/or calculations, resulting in misalignments, which is reported as shortage or surplus.

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Figure 2-130: ESJ Subbasin Projected Agricultural Demand in the PCBL-CC-PMA Version 3.0 Figure 2-131: ESJ Subbasin Projected Urban Demand in the PCBL-CC-PMA Version 3.0 EXHIBIT 1
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2.4.9.2 Hydrologic Groundwater Budget
Pumping in the PCBL-CC-PMA Version 3.0 remains the largest component in the groundwater budget with an annual average 846 TAFY. The PCBL-CC-PMA Version 3.0 offsets this pumping with 274 TAFY of deep percolation, a net gain from stream of 260 TAFY, 187 TAFY of other recharge, and a total subsurface inflow of 91 TAFY annually. The cumulative change in groundwater storage can be calculated from the annual change in groundwater storage. Due to inherent uncertainties in model input data, calculations, and calibration, all budget components have a degree of uncertainty. Given this uncertainty, the projected long-term average annual groundwater storage deficit in ESJ Subbasin in the PCBL-CC-PMA Version 3.0 is 34 TAFY, indicating that groundwater overdraft is still occurring even with the Category A projects due to the impacts climate change on the Subbasin. These annual averages are shown in Table 2-28. The groundwater budgets, with average cumulative change in storage, are shown for the ESJ Subbasin in Figure 2-132.

Table 2-28 also includes the PCBL Version 3.0 results and a Category A projects benefit calculated as the PCBL-PMA Version 3.0 results minus the PCBL Version 3.0 results. While the groundwater storage deficit in the PCBL Version 3.0 is projected to be corrected through the implementation of Category A projects as seen in PCBL-PMA Version 3.0, the modeling shows that when climate change is factored in for the PCBL-CC-PMA Version 3.0, there is still additional work (e.g., projects and/or management actions) that may need to be done to maintain subbasin sustainability. The PCBL-CC Version 3.0 has a projected overdraft of 56 TAFY. When projects are added in, as simulated in PCBL-CCPMA Version 3.0, this overdraft amount is reduced to 34 TAFY.

Compared to the PCBL-CC Version 3.0, with Category A projects modeled, the PCBL-CC-PMA Version 3.0 has 34 TAFY less groundwater pumping due to the new in-lieu recharge projects, 19 TAFY more recharge (both direct recharge projects and canal seepage losses for the in-lieu recharge projects), and 17 TAFY less stream seepage into the groundwater system due to higher groundwater levels. Other hydrologic groundwater budget component differences are small between the PCBL-CC Version 3.0 and PCBL-CC-PMA Version 3.0 simulations.

Table 2-28: ESJ Hydrologic Groundwater Budget Annual Average Comparison Between the PCBLCC and the PCBL-CC-PMA Version 3.0 Annual Average
Hydrologic Groundwater Budget
Component

PCBL-CC PCBL-CC-PMA
Version 3.0
PMA Benefit
(PCBL-CCPMA Version

3.0 minus

PCBL-CC)
Deep Percolation (AF) 268 274 6
Other Recharge (AF) 168 187 19
Net Stream Seepage (AF) 276 260 -17
Net Boundary Inflow (AF) 111 91 -20
Groundwater Pumping (AF) 879 846 -34
Change in Groundwater Storage (AF) -56 -34 22
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Figure 2-132: Eastern San Joaquin Subbasin Projected Hydrologic Groundwater Budget in the

PCBL-CC-PMA
For a comparison of the PCBL water budget results with and without PMAs and with and without climate change, please see Appendix 2-C of this updated GSP.

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3. SUSTAINABLE MANAGEMENT CRITERIA
Several requirements of Groundwater Sustainability Plans (GSPs) fall under the heading of “Sustainable Management Criteria”. These criteria include:
• Sustainability Goal
• Undesirable Results
• Minimum Thresholds
• Measurable Objectives
The Eastern San Joaquin (ESJ) GSP developed these criteria based on information about the Subbasin developed in the hydrogeologic conceptual model (Section 2.1), the descriptions of historical and current groundwater conditions (Section 2.2 and 2.3, respectively), the water budget (Section 2.4), and input from stakeholders during the GSP development process (Section 1.3.4). The sustainable management criteria were developed by working with the Eastern San Joaquin Groundwater Authority Board of Directors (ESJGWA Board), Advisory Committee, and Groundwater Sustainability Workgroup (Workgroup) over several months in 2018 and into 2019 and were revised to address Recommended Corrective Actions (RCAs) presented by the California Department of Water Resources (DWR) in their July 6, 2023 determination letter approving the 2022 Eastern San Joaquin GSP.

This amended GSP considers the six sustainability indicators defined by the Sustainable Groundwater Management Act (SGMA) in the development of sustainable management criteria. SGMA allows several pathways to meet the distinct local needs of each groundwater basin, including development of sustainable management criteria, usage of other sustainability indicators as a proxy, and identification of indicators as not being applicable to the basin. This GSP relies on groundwater levels as a proxy for minimum thresholds and measurable objectives for reduction in groundwater storage and eliminates seawater intrusion as an applicable sustainability criterion.

3.1 SUSTAINABILITY GOAL
The California Water Code (Water Code) defines sustainable groundwater management as “the management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results” (CA Water Code §10721). The planning and implementation horizon includes a 20-year implementation period until 2040 where sustainability is achieved and a 50-year planning period where pumping is maintained within the sustainable yield. The sustainability goal reflects this requirement and succinctly states the Groundwater Sustainability Agencies’ (GSAs’) objectives and desired conditions of the Subbasin.

The sustainability goal description for the Eastern San Joaquin Subbasin is to maintain an economically-viable groundwater resource for the beneficial use of the people of the Eastern San Joaquin Subbasin by operating the Subbasin within its sustainable yield or by modification of existing management to address future conditions. This goal will be achieved through the implementation of a mix of supply and demand type projects consistent with the GSP implementation plan (see Chapter 6: Projects and Management Actions and Chapter 7: Plan Implementation).

Groundwater levels in the Subbasin may continue to decline during the implementation period. However, as projects are implemented and basin operations are modified, sustainable groundwater management will be achieved, and levels will stabilize on a long-term average basis. The Subbasin will be managed to prevent undesirable results throughout the implementation period, despite the possible decline of groundwater elevations. This sustainability goal is supported by locally-defined minimum thresholds that will avoid undesirable results. Demonstration of stable groundwater levels on a long-term average basis combined with the absence of undesirable results will ensure the Subbasin is operating within its sustainable yield (see Section 2.4.6) and the sustainability goal will be achieved.

An explanation of how the goal will be achieved is included in Chapter 6: Projects and Management Actions.

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Sustainable Management Criteria November 2024
Sustainable Management Criteria Definitions
• Undesirable Results – Significant and unreasonable negative impacts associated with each sustainability indicator, avoidance of which is used to guide development of GSP components • Minimum Threshold – Quantitative threshold for each sustainability indicator used to define the point at which undesirable results may begin to occur
• Measurable Objective – Quantitative target that establishes a point above the minimum threshold that allows for a range of active management in order to prevent undesirable results • Interim Milestones – Targets set in increments of 5 years over the implementation period of the GSP to put the basin on a path to sustainability
• Margin of Operational Flexibility – The range of active management between the measurable objective and the minimum threshold
See Figure 3-1 for a graphic that demonstrates the relationship between the Sustainable Management Criteria terms.

Figure 3-1: Sustainable Management Criteria Definitions Graphic (Groundwater Levels Example) EXHIBIT 1
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Sustainable Management Criteria November 2024

3.2 UPDATES TO SUSTAINABILITY INDICATORS
The Eastern San Joaquin Groundwater Authority (ESJGWA) received a Consultation Initiation Letter (Letter) on November 18, 2021 (Appendix 3-A) from DWR. The Letter identified two potential deficiencies with the Eastern San Joaquin Groundwater Subbasin (Subbasin) GSP which precluded DWR’s approval, as well as potential corrective actions to address each potential deficiency. The Letter thus initiated consultation between DWR, the Plan Manager, and the Subbasin’s GSAs regarding the amount of time needed to address the potential deficiencies and corrective actions. A subsequent meeting with DWR was held on April 4, 2022 to discuss the Subbasin’s proposed approach to addressing the identified deficiencies. Revisions to the sustainability indicators and sustainable management criteria were subsequently incorporated into the 2020 Eastern San Joaquin GSP and a revised GSP submitted to DWR on July 27, 2022. In a July 6, 2023 letter, DWR staff concluded that the GSAs had taken sufficient actions to correct deficiencies identified by DWR and approved the 2022 Plan (see Appendix 3-B).

In their July 2023 letter, DWR identified the eight RCAs for the GSAs to consider during preparation of its 5-year Periodic Evaluation. Per DWR’s October 2023 guidance entitled Groundwater Sustainability Plan Implementation: A Guide to Annual Reports, Periodic Evaluations, & Plan Amendments, “Plan Amendments are completed at the discretion of the GSAs. SGMA and the GSP Regulations do not establish when an amendment is required, nor do they describe what components of the Plan should be amended. In general, however, the more significant or material a change to a GSP or its implementation, the more likely a Plan Amendment is warranted.” As the 2024 ESJ Subbasin Periodic Evaluation and associated consideration of DWR’s RCAs as contained in their July 2023 determination letter resulted in substantive changes to both sustainable management criteria (SMC) and representative monitoring networks (RMNs), the ESJ GSAs have opted to amend their 2022 GSP. This amended GSP chapter incorporates the responses and associated work to address DWR’s eight RCAs, reflecting changes made to the Subbasin sustainability indicators and SMC. Documentation of modifications made to Subbasin sustainability indicators and SMC and additional explanation as to how the Subbasin sustainability indicators and SMC were determined can be found in the appendices as follows:
• RCA No. 1(a) through 1(d) addressed in Appendix 3-C
• RCA No. 2 addressed in Appendix 3-D
• RCA No. 3 addressed in Appendix 3-E
• RCA No. 4 addressed in Appendix 3-E
• RCA No. 5 addressed in Appendix 3-F
• RCA No. 6 addressed in Appendix 3-G
• RCA No. 7 addressed in Appendix 3-F
• RCA No. 8 addressed in Appendix 3-F

3.3 REVISED SUSTAINABILITY INDICATORS

3.3.1 Chronic Lowering of Groundwater Levels

3.3.1.1 Undesirable Results

3.3.1.1.1 Description of Undesirable Results
SGMA defines undesirable results related to chronic lowering of groundwater as:

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Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon. Overdraft during a period of drought is not sufficient to establish a chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reductions in groundwater levels or storage during a period of drought are offset by increases in groundwater levels or storage during other periods.

An undesirable result for chronic lowering of groundwater levels in the Eastern San Joaquin Subbasin is experienced if sustained groundwater levels are too low to satisfy beneficial uses within the Subbasin over the planning and implementation horizon of this GSP (see Section 1.3.1 for a discussion of beneficial uses and users). Potential impacts and the extent to which they are considered significant and unreasonable were determined by the ESJGWA Board with input by the Advisory Committee, Workgroup, Project Management Committee, and members of the public. During development of and revisions to the GSP, potential undesirable results identified by stakeholders included a significant and unreasonable:
• Number of wells going dry
• Reduction in the pumping capacity of existing wells
• Increase in pumping costs due to greater lift
• Need for deeper well installations or lowering of pumps • Adverse impacts to environmental uses and users, including interconnected surface waters and groundwater dependent ecosystems (GDEs)

3.3.1.1.2 Identification of Undesirable Results
An undesirable result is considered to occur during GSP implementation when at least 25 percent of representative monitoring wells used to monitor groundwater levels (5 of 2110 wells in the Subbasin) fall below their minimum level thresholds for two consecutive years.

Two consecutive years of minimum threshold exceedances are used to determine if an undesirable result has occurred and to establish a pattern rather than indicate an isolated event. The lowering of groundwater levels during dry or critically-dry years is not considered to be unreasonable unless the levels do not rebound to above the thresholds following wet conditions or are otherwise mitigated through adaptive management or implementation of projects and management actions. While statistically, three data points are required to establish a trend, three years of exceedances was felt to be too extreme, whereas a single exceedance was not sufficient to establish a trend. Therefore, the two consecutive years was selected as part of this definition.

At least 25 percent of representative monitoring wells used to monitor groundwater levels falling below their minimum thresholds for two consecutive years was presented to the Eastern San Joaquin Technical Advisory Committee (ESJ TAC) during the April 10, 2019 meeting and was approved by the Eastern San Joaquin Groundwater Authority (ESJGWA) Board during the May 8, 2019 meeting. The 2020 GSP used the Eastern San Joaquin Water Resources Model (ESJWRM) results under the projected conditions baseline scenario to evaluate impacts associated minimum threshold exceedances. The model results considered in determining that a 25 percent exceedance threshold were sufficient to determine that undesirable results would occur subbasin-wide (e.g., were not a localized event). The 25% exceedance threshold was further evaluated in response to DWR’s comments in their 2022 Determination letter, specifically as it relates to both domestic and municipal supply wells and GDEs in the Subbasin. See Appendix 1-G for 10 Three wells have been added to the representative monitoring network for groundwater levels since the 2020 GSP. One well has historical data (01S10E04C001M) and SMC have been established for that well. The other two were newly constructed under the TSS program and do not have established SMC as of this Amended GSP due to a lack of data.

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analyses around potential domestic and public supply well impacts and GDE impacts associated with the 25 percent exceedance portion of the definition of undesirable results.

3.3.1.1.3 Potential Causes of Undesirable Results
The Eastern San Joaquin Subbasin is currently designated as a critically overdrafted subbasin by DWR, a designation originally placed on the Subbasin in 1980 (CA DWR, 1980). The Subbasin has experienced undesirable results related to chronic lowering of groundwater levels in the past, which resulted in the deepening of wells. These historical undesirable results, as well as the widespread deepening of Subbasin wells, were identified through anecdotal data provided by GSAs and through review of prior planning documents, including the 2014 Eastern San Joaquin Integrated Regional Water Management Plan (ESJ IRWMP), which indicates that water levels fell to “unprecedented levels” in the fall of 1992, and that “many private groundwater users were forced to modify or deepen wells during the prolonged 1986-1992 drought period” (Eastern San Joaquin County GBA, 2014). Due to these prior efforts to mitigate low groundwater levels, undesirable results in the Subbasin were remedied. Each ESJGWA member GSA indicated, through multiple meetings, that no current undesirable results exist in their GSA, largely citing these prior large-scale well-deepening efforts and significant undertakings to augment surface water supplies.

Future undesirable results could result from insufficient groundwater recharge and/or offset or delays in implementation of GSP programs or projects due to increased demand or regulatory, permitting, or funding obstacles.

3.3.1.1.4 Potential Effects of Undesirable Results
If groundwater levels were to cause undesirable results, effects could include de-watering of a subset of the existing groundwater infrastructure, starting with the shallowest wells, which are generally domestic wells, and adverse effects on GDEs, to the extent connected with the production aquifer. Lowering levels to this degree could necessitate changes in irrigation practices and crops grown and could cause adverse effects to property values and the regional economy.

Additionally, undesirable results due to declining groundwater levels could adversely affect current and projected municipal uses translating into increased costs for potable water supplies.

Potential effects of undesirable results related to GDEs is an area that has been identified as a data gap requiring further study, including through future shallow groundwater monitoring efforts discussed in Section 4.7. However, current databases were used in updated mapping of GDEs and the associated analysis of potential impacts as a result of the undesirable results definition for this sustainability parameter. See Appendix 1-G for more information.

3.3.1.2 Minimum Thresholds
The minimum thresholds for chronic lowering of groundwater levels are the shallower at each representative monitoring well site of the following:
• 2015 groundwater level low with a buffer of 100 percent of historical range applied, or • The 10th percentile domestic well total depth of wells within a 3-mile radius of the monitoring well.11,12 As a starting point, a potential minimum threshold was considered for each representative monitoring well based on groundwater level data collected in 2015, if available. A buffer was subtracted from the minimum 2015 groundwater elevation. The buffer was calculated by finding the difference between the minimum and maximum groundwater level over the historical record for each representative monitoring well. The addition of the buffer provides a range of 11 A radius of 2 miles was used for well 03N07E21L003 to reflect domestic well depths in close proximity to the Mokelumne River.
12 In municipalities with ordinances requiring the use of City water (water provided by the City’s municipal wells), the 10th percentile municipal well depth is used in place of the 10th percentile domestic well depth criteria.

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operational flexibility in which groundwater levels may continue to decline during implementation of projects and management actions until sustainable yield is reached. The buffer allows for flexibility to account for natural fluctuations in groundwater levels but avoids significant and unreasonable impacts to groundwater levels.

The ESJGWA Board determined that dewatering of domestic wells and impacts to small community drinking water systems may be a potential undesirable result that could be used to confirm the adequacy of the minimum threshold methodology. Domestic wells and those associated with small community water systems are generally shallower than agricultural and municipal wells and thus more sensitive to undesirable effects such as dry wells. Additionally, the loss of a domestic well usually results in a loss of water for consumption, cooking, and sanitary purposes, which can often have substantial impacts on the users of the water and can be financially difficult for the well owner to replace. The 10th percentile domestic well depth (i.e., the depth of the top 10th percent most shallow well) was examined within a radius around the monitoring well representative of local conditions. A radius of 3 miles around each representative monitoring well was used to identify the 10th percentile domestic well construction depth. For representative monitoring well 03N07E21L003, a 2-mile radius was used due to variations in groundwater levels due to its proximity to the Mokelumne River. The 3-mile radius around each representative monitoring well (including the 2-mile radius of monitoring well 03N07E21L003 and the two additional radii that do not contain representative monitoring wells), includes over 4,000 domestic wells, 165 public supply wells and 58 community water systems in the Subbasin. In cases where the 10th percentile domestic well depth was shallower than the historical drought low with the buffer, that value was developed as the minimum threshold to prevent undesirable results associated with dewatering wells in the Subbasin.

Domestic and public water system well data were retrieved from the Online System for Well Completion Reports (OSWCR) database, which is sparsely populated with information on total casing depth, screening intervals, and the age of the well. The 10th percentile well depth was chosen due to the uncertainty in the database and to account for the fact that domestic wells (predominantly) may have been drilled to a very shallow depth prior to the current well drilling standards enforced by local jurisdictions and/or have reached the end of their lifecycle. The 10th percentile domestic well depth for groundwater levels is protective of approximately 90 percent of the domestic wells in the OSWCR dataset and is used as a criterion for determining if a decline in groundwater levels is significant and unreasonable under SGMA. In municipalities with ordinances requiring the use of City water (water provided by the City’s municipal wells), the 10th percentile municipal well depth is used in place of the 10th percentile domestic well depth criteria.

Figure 3-2 shows the location of groundwater level representative monitoring wells throughout the Eastern San Joaquin Subbasin. This updated representative monitoring network includes two new multi-completion wells constructed in 2021 by DWR under the Technical Support Services (TSS) program. Table 3-1 lists the corresponding numeric minimum thresholds at each representative monitoring well and the basis. Additional data on the monitoring wells and minimum thresholds, including hydrographs of historical observed data and domestic well analysis, are provided in Appendix 3-H and 3-I.

The basis for design and selection of the SMCs is the lowest drought-related groundwater conditions observed. The ESJGWA and GSAs focused the GSP goals on the long-term sustainability of the Subbasin and implementation of projects that would help all beneficial users to have a reliable and resilient water supply, even in time of drought, and provide the ability to respond to climate change. The ESJGWA and GSAs are supportive of ongoing agricultural, urban, and industrial water conservation efforts and of achieving the highest levels of water use efficiency technically achievable. It should be noted that water conservation programs have been successful in reducing urban and agricultural water demands such that those demands have become “hardened” and are less able to be reduced in time of drought without real impacts to the quality of life or economy. GSP projects and management actions are designed to reduce overdraft, and to provide sustainable supplies through a drought without severe impacts to quality of life or the economy.

For the two new multi-completion wells have been added to the representative monitoring network for groundwater levels, and for any new monitoring wells that may be added to the representative monitoring network in the future, SMCs for these new wells will be established after at least four years of data have been collected, including data for at EXHIBIT 1
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least one wet year and one dry or critical year during that time period. If wet and dry/critical years do not occur during this initial period, then additional years of data collection may be required before establishing SMCs.

Minimum thresholds for these and other new wells that may be constructed in the future will be established based on adjusted recent groundwater levels from a dry/critical year. The adjustment of groundwater levels is the difference in simulated groundwater levels in ESJWRM between Water Year 2015 (a dry year) and the recent dry/critical year when groundwater level observations are measured. The calculation for the minimum threshold is:

𝑀𝑖𝑛𝑖𝑚𝑢𝑚 𝑇ℎ𝑟𝑒𝑠ℎ𝑜𝑙𝑑
= 𝑂𝑏𝑠𝑒𝑟𝑣𝑒𝑑 𝑅𝑒𝑐𝑒𝑛𝑡 𝐷𝑟𝑦/𝐶𝑟𝑖𝑡𝑖𝑐𝑎𝑙 𝐺𝑊𝐿 − (𝑆𝑖𝑚𝑢𝑙𝑎𝑡𝑒𝑑 𝑅𝑒𝑐𝑒𝑛𝑡 𝐷𝑟𝑦 𝑌𝑒𝑎𝑟 𝐺𝑊𝐿𝑠 − 𝑆𝑖𝑚𝑢𝑙𝑎𝑡𝑒𝑑 2015 𝐺𝑊𝐿𝑠)
As a hypothetical example, suppose Water Year 2027 is a critical year and the observed groundwater elevation for Well A is 75 feet mean sea level (msl) in 2027. Assuming that the simulated groundwater elevations in ESJWRM at Well A increase by 8 feet between 2015 and 2027. The minimum threshold would be 75 feet minus 8 feet, or 67 feet msl. In the absence of historical data, this methodology is meant to estimate historical conditions as closely as possible.

The GSP was not targeted toward emergency responses to drought or the short-term impacts associated with drought since this is the focus of the County Office of Emergency Services (OES) and a requirement for the water purveyors.

In addition, the prevailing urban water management plans (UWMPs) and agricultural water management plans (AWMPs) identify water conservation goals and demand reduction targets, including water shortage contingency plans, and the ESJGWA and GSAs are supportive of those plans (and the drought contingency responses) and will encourage the lead agencies for those plans to implement actions and programs consistent with local and state requirements. The ESJGWA will work to better coordinate with the OES and urban purveyors to support emergency drought response efforts. The ESJGWA and GSP development has included representatives from the urban suppliers and will continue to seek opportunities to engage with OES, the urban purveyors and to work to identify mutual goals, objectives and project opportunities.

Additionally, the ESJGWA and GSAs will evaluate other programs as part of an adaptive management strategy (including a demand reduction strategy), and along with an annual evaluation of Subbasin conditions, will continue outreach efforts to domestic well owners and small water systems regarding information related to forecasted water levels with and without project implementation to inform subsequent investments decisions for well improvement and replacement; produce and distribute current and forecasted groundwater level information to well permit applicants to inform the permitting process; review well standards to evaluate opportunities to establish standards to better reflect current and forecasted groundwater level conditions; and actively promote small systems interties and/or consolidation of their systems to achieve supply reliability.

If drinking water impacts are observed during GSP implementation as a result of the established minimum thresholds, the ESJGWA will evaluate the need to revise the minimum threshold methodology and/or implement additional projects or management actions, such as the Subbasin’s domestic well mitigation program (Appendix 3-J) to mitigate such impacts (as described in Appendix 3-C). The ESJGWA and GSAs will evaluate other programs as part of the adaptive management strategy, and annual program evaluation and reporting.

The future amendments to the Subbasin GSP will more closely evaluate and include information on UWMP water shortage contingency plans, and the ESJGWA will coordinate with the County OES to support emergency drought responses and plans.

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Figure 3-2: Location of Representative Monitoring Wells for Groundwater Levels EXHIBIT 1
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Table 3-1: Minimum Thresholds for Chronic Lowering of Groundwater Levels Narrative Description
The minimum threshold is set at the 2015 groundwater level low with a buffer of 100 percent of historical range applied, or the 10th percentile domestic well depth, whichever is shallower. In municipalities with ordinances requiring the use of City water, the 10th percentile municipal well depth is used in place of the 10th percentile domestic well depth criteria.

Numeric Minimum Thresholds
GSA Well is Located
in1 Well ID Minimum Threshold (feet mean sea level [MSL]) Basis for Threshold CSJWCD 01S09E05H002 -49.8 10ᵗʰ percentile domestic well depth CSJWCD 01N07E14J002 -93.9 2015 groundwater level with a buffer of 100 percent of historical range
City of Lodi Lodi City Well #2 -34.4 2015 groundwater level with a buffer of 100 percent of historical range
City of Manteca Manteca 18 -19.0 2015 groundwater level with a buffer of 100 percent of historical range
City of Stockton Swenson-3 -26.6 2015 groundwater level with a buffer of 100 percent of historical range
Eastside GSA 01S10E26J001M 43.7 2015 groundwater level with a buffer of 100 percent of historical range
Eastside GSA 01S10E04C001M 54.7 2015 groundwater level with a buffer of 100 percent of historical range
LCWD 02N08E15M002 -124.1 10ᵗʰ percentile domestic well depth LCSD #3 Bear Creek -73.8 2015 groundwater level with a buffer of 100 percent of historical range
NSJWCD 04N07E20H003M -80.5 2015 groundwater level with a buffer of 100 percent of historical range
NSJWCD 03N07E21L003 -94.0 2015 groundwater level with a buffer of 100 percent of historical range
NSJWCD NSJWCD-012 TBD New SMC methodology
OID Hirschfeld (OID-8) 7.9 2015 groundwater level with a buffer of 100 percent of historical range
OID Burnett (OID-4) 60.8 2015 groundwater level with a buffer of 100 percent of historical range
SDWA 02S07E31N001 0.8 2015 groundwater level with a buffer of 100 percent of historical range
SSJ GSA 02S08E08A001 0.6 2015 groundwater level with a buffer of 100 percent of historical range
SEWD 02N07E03D001 -113.7 10ᵗʰ percentile domestic well depth SEWD 01N09E05J001 -86.8 10ᵗʰ percentile domestic well depth SEWD 02N07E29B001 -130.1 10ᵗʰ percentile domestic well depth SEWD SEWD-012 TBD New SMC methodology
WID 04N05E36H003 -31.1 2015 groundwater level with a buffer of 100 percent of historical range
WID 03N06E05N003 -35.1 2015 groundwater level with a buffer of 100 percent of historical range
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WID 04N05E24J004 -31.2 2015 groundwater level with a buffer of 100 percent of historical range
1 Acronyms defined: Central San Joaquin Water Conservation District (CSJWCD), Eastside San Joaquin GSA (Eastside GSA), Linden County Water District (LCWD), Lockeford Community Services District (LCSD), North San Joaquin Water Conservation District (NSJWCD), Oakdale Irrigation District (OID), South Delta Water Agency (SDWA), South San Joaquin GSA (SSJ GSA), Stockton East Water District (SEWD), Woodbridge Irrigation District (WID). 2 New multi-completion well constructed in 2021 under the DWR Technical Support Services (TSS) program.

3.3.1.3 Measurable Objectives and Interim Milestones
Measurable objectives are quantitative goals that reflect the desired Subbasin condition and allow the Subbasin to achieve its sustainability goal. The measurable objective is set to allow a reasonable margin of operational flexibility between minimum thresholds to allow for active management of the Subbasin during dry periods without reaching the minimum threshold. The margin of operational flexibility is intended to accommodate droughts, climate change, conjunctive use operations, or other groundwater management activities. The margin of operational flexibility is defined as the difference between the minimum threshold and the measurable objective. The measurable objective for chronic lowering of groundwater levels is defined as the 2015 groundwater level low values.

Table 3-2 lists the measurable objectives for each representative monitoring well. The margin of operational flexibility is defined at each well as the difference between the minimum and maximum groundwater level over the historical record for that well.

Table 3-2: Measurable Objective for Chronic Lowering of Groundwater Levels Narrative Description
The measurable objective is set at the 2015 groundwater level low.

Numeric Measurable Objectives
GSA Well is Located in Well ID Measurable Objective (feet MSL)
CSJWCD 01S09E05H002 -8.6
CSJWCD 01N07E14J002 -49.9
City of Lodi Lodi City Well #2 0.6
City of Manteca Manteca 18 2.8
City of Stockton Swenson-3 -19.3
Eastside GSA 01S10E26J001M 81.7
Eastside GSA 01S10E04C001M 76.4
LCWD 02N08E15M002 -63.2
LCSD #3 Bear Creek -51.8
NSJWCD 04N07E20H003M -35.5
NSJWCD 03N07E21L003 -51.5
NSJWCD NSJWCD-011 TBD
OID Hirschfeld (OID-8) 31.5
OID Burnett (OID-4) 79.7
SDWA 02S07E31N001 12.3
SSJ GSA 02S08E08A001 24.0
SEWD 02N07E03D001 -61.7
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Narrative Description
The measurable objective is set at the 2015 groundwater level low.

Numeric Measurable Objectives
GSA Well is Located in Well ID Measurable Objective (feet MSL)
SEWD 01N09E05J001 -22.6
SEWD 02N07E29B001 -80.4
SEWD SEWD-011 TBD
WID 04N05E36H003 -5.1
WID 03N06E05N003 -14.1
WID 04N05E24J004 -6.2

1. New multi-completion well constructed in 2021 under the DWR Technical Support Services (TSS) program.

Similar to minimum thresholds, for the two new multi-completion wells have been added to the representative monitoring network for groundwater levels, and for any new monitoring wells that may be added to the representative monitoring network in the future, measurable objectives for these new wells will be established after at least four years of data have been collected, including data for at least one wet year and one dry or critical year during that time period.

If wet and dry/critical years do not occur during this initial period, then additional years of data collection may be required before establishing SMCs.

For new wells lacking sufficient historical data, measurable objectives will be established from an adjustment in groundwater levels from a wet year. The adjustment will add the difference in simulated groundwater levels from ESJWRM between Water Year 2011 (a wet year) and a recent wet year when groundwater level observations are collected. The calculation for measurable objectives is:

𝑀𝑒𝑎𝑠𝑢𝑟𝑎𝑏𝑙𝑒 𝑂𝑏𝑗𝑒𝑐𝑡𝑖𝑣𝑒𝑠
= 𝑂𝑏𝑠𝑒𝑟𝑣𝑒𝑑 𝑅𝑒𝑐𝑒𝑛𝑡 𝑊𝑒𝑡 𝐺𝑊𝐿 + (𝑆𝑖𝑚𝑢𝑙𝑎𝑡𝑒𝑑 𝑅𝑒𝑐𝑒𝑛𝑡 𝑊𝑒𝑡 𝑌𝑒𝑎𝑟 𝐺𝑊𝐿 − 𝑆𝑖𝑚𝑢𝑙𝑎𝑡𝑒𝑑 2011 𝐺𝑊𝐿𝑠)
As a hypothetical example, suppose Water Year 2026 is a wet year, and the observed groundwater elevation for Well A is 82 feet msl that year. Suppose that the simulated groundwater elevations in ESJWRM at Well A decrease by 15 feet between Water Year 2011 and 2026. The measurable objective would be 82 feet minus negative 15 feet, equaling 97 feet msl.

To assist the Subbasin in reaching the measurable objective for groundwater levels, interim milestones for 2025, 2030, and 2035 were developed to keep implementation on track. Interim milestones are based on achieving the sustainability goal within the 20-year time period provided by SGMA.

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Table 3-3 shows the 5-year milestones, which follow a stepwise trend between the current condition and the measurable objective. Fall 2015 groundwater levels were used to define current conditions where data were available, and the average of fall 2013, fall 2014, and fall 2016 were used where fall 2015 data were not available. For new wells lacking sufficient historical data, interim milestones will be established as appropriate at the time minimum thresholds and measurable objectives are established for the wells. Interim milestones will depend on the date when these other SMC were developed.

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Table 3-3: Interim Milestones for Chronic Lowering of Groundwater Levels Narrative Description
5-year milestones are assumed to remain similar to current for the first 10 years and then follow along a linear trend between the current condition and the measurable objective.

Numeric Interim Milestones
GSA Well is Current Measurable Interim Milestones
Located in Well ID Condition
(feet MSL)
Objective
(feet MSL) 2025 2030 2035
CSJWCD 01S09E05H002 -8.7 -8.6 -8.7 -8.7 -8.7
CSJWCD 01N07E14J002 -49.9 -49.9 -49.9 -49.9 -49.9
City of Lodi Lodi City Well #2 0.61 0.6 0.6 0.6 0.6
City of Manteca Manteca 18 9.1 2.8 9.1 9.1 6.0
City of Stockton Swenson-3 -19.3 -19.3 -19.3 -19.3 -19.3 Eastside GSA 01S10E26J001M 81.7 81.7 81.7 81.7 81.7
Eastside GSA 01S10E04C001M 78.0 76.4 78.0 78.0 77.2
LCWD 02N08E15M002 -63.2 -63.2 -63.2 -63.2 -63.2
LCSD #3 Bear Creek -49.3 -51.8 -49.3 -49.3 -50.6
NSJWCD 04N07E20H003M -35.5 -35.5 -35.5 -35.5 -35.5
NSJWCD 03N07E21L003 -51.5 -51.5 -51.5 -51.5 -51.5
NSJWCD NSJWCD-012 TBD TBD TBD TBD TBD
OID Hirschfeld (OID-8) 31.5 31.5 31.5 31.5 31.5
OID Burnett (OID-4) 79.7 79.7 79.7 79.7 79.7
SDWA 02S07E31N001 13.81 12.3 13.8 13.8 13.1
SSJ GSA 02S08E08A001 22.21 24.0 22.2 22.2 23.1
SEWD 02N07E03D001 -61.7 -61.7 -61.7 -61.7 -61.7
SEWD 01N09E05J001 -20.2 -22.6 -20.2 -20.2 -21.4
SEWD 02N07E29B001 -49.81-80.4 -49.8 -49.8 -65.1
SEWD SEWD-012 TBD TBD TBD TBD TBD
WID 04N05E36H003 -5.1 -5.1 -5.1 -5.1 -5.1
WID 03N06E05N003 -14.1 -14.1 -14.1 -14.1 -14.1
WID 04N05E24J004 -6.2 -6.2 -6.2 -6.2 -6.2

1. Current Condition is the average of fall groundwater levels for 2013-2016

2. New multi-completion well, constructed in 2021 under the DWR Technical Support Services (TSS) program.

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3.3.2 Reduction in Groundwater Storage

3.3.2.1 Undesirable Results

3.3.2.1.1 Description of Undesirable Results
The ESJGWA has determined that an undesirable result for the reduction of groundwater storage is experienced if sustained groundwater storage volumes are insufficient to satisfy beneficial uses within the Subbasin over the planning and implementation horizon of this GSP (see Section 1.3.1 for a discussion of beneficial uses and users).

Undesirable results related to groundwater storage in the Subbasin have not occurred historically, are not currently occurring, and are not likely to occur in the future. As discussed in the current and historical groundwater conditions section of this GSP (Section 2.2), there is a large volume (approximately 53 million acre-feet [MAF]) of freshwater in storage. An analysis of groundwater storage using the Eastern San Joaquin Water Resources Model (ESJWRM) Version 1.1 was conducted for the 2020 GSP to evaluate groundwater storage conditions between 1996 and 2015.

The results of this analysis showed a range of fluctuation from 1996 to 2015 of approximately 0.01 percent per year.

The updated ESJWRM Version 3.0 was subsequently used to evaluate the range of fluctuations from 1996 to 2023; the results of this modeling showed a similar result. See Section 2.2.2 for additional quantification of groundwater storage. A discussion of the geology of the Subbasin can be found in Section 2.1. Information on the updated ESJWRM Version 3.0 model can be found in Appendix 2-C.

3.3.2.1.2 Identification of Undesirable Results
An undesirable result occurs when groundwater storage volumes are insufficient to satisfy beneficial uses within the Subbasin. To identify a volume associated with undesirable results, the ESJWRM Version 1.1 was run for the 2020 GSP to estimate the volume of groundwater storage needed to meet beneficial uses. This analysis determined that groundwater demand for beneficial use occurs within the shallowest 23 MAF of the Subbasin, as this is roughly the zone corresponding to the depth at which pumping occurs and is reasonably expected to occur in the future. Based on this analysis, it was estimated that overlying pumpers have limited access equating to approximately the shallowest 23 MAF of groundwater storage in the Subbasin; therefore, the 2020 GSP defined an undesirable result would occur if groundwater storage levels were depleted by 23 MAF. However, if 23 MAF of groundwater were removed from the Subbasin, groundwater levels would have to drop substantially below the MTs set for groundwater levels. As such, impacts would be experienced under the definition of undesirable results for groundwater levels long before the 23 MAF would have been removed from the Subbasin.

Given that the chronic lowering of groundwater levels is directly related to overdraft conditions, if an undesirable result for groundwater levels occurs first, then mitigation will be activated to respond to the undesirable result, effectively making groundwater level SMC already protective of beneficial uses of groundwater noted in the original undesirable result definition. And as groundwater levels are directly measurable and groundwater storage is not, it is reasonable to use groundwater levels as a proxy for reductions in groundwater storage. To evaluate the approximate volume of groundwater that could potentially be removed from storage before impacts associated with groundwater level undesirable results were experienced, additional analyses were conducted using the updated ESJWRM Version 3.0 model. Model scenarios were simulated where various groupings of five representative monitoring network wells dropped to their associated minimum thresholds under the Projected Conditions Baseline with Climate Change (PCBLCC) Version 3.0 scenario. The various well groups were chosen based on proximity to the Subbasin’s groundwater depression area, historical sustainable management criteria performance, and spatial distribution throughout the Subbasin. The resulting reduction in groundwater storage from each of these test scenarios was recorded and found to vary from 10 MAF to 13 MAF. As such, the undesirable result for reductions in groundwater storage was updated to be between 10 to13 MAF. Defining a range in storage for this undesirable result acknowledges the uncertainty associated with the model in terms of storage. As the climate change scenario was used in the analysis, it also allows for consideration of the uncertainty associated with how extreme impacts of climate changes may be and where impacts EXHIBIT 1
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within the Subbasin. Additional detail on the update to the undesirable result for storage can be found in Appendix 3- E.

3.3.2.1.3 Potential Causes of Undesirable Results
While reduction of 23 MAF within the SGMA planning horizon of 2040 is highly unlikely, an event of a catastrophic nature or prolonged and exaggerated increases in the mining of groundwater due to extreme and severe drought or major changes in groundwater management over time could cause a reduction of groundwater storage to a significant and unreasonable level, and it is highly likely that the minimum thresholds established for groundwater levels would have been exceeded before this reduction in groundwater in storage would occur. Based on the analysis contained in Appendix 3-E, between approximately 10 and 13 MAF of groundwater would need to be removed from Subbasin storage to trigger undesirable results relating to groundwater levels. And as groundwater levels are a proxy for change in groundwater storage, these values also trigger undesirable results for the reduction in groundwater storage.

Section 7.4.4 references factors that could affect the availability of surface water, including State Water Resources Control Board (SWRCB) plans to reduce flows available for use by 40-60 percent as part of the Water Quality Control Plan for the Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Estuary (Bay-Delta Plan).

3.3.2.1.4 Potential Effects of Undesirable Results
If groundwater levels were to reach levels causing undesirable results, significant and unreasonable effects could include degradation of produced water quality from groundwater sources; insufficient fresh groundwater to access in drought years; increased cost of access; and reduction in beneficial uses, such as domestic supply and changes to agriculture.

3.3.2.2 Minimum Thresholds
This GSP uses groundwater level minimum thresholds as a proxy for the reduction in groundwater storage sustainability indicator.

GSP regulations allow GSAs to use groundwater levels as a proxy metric for any sustainability indicator provided the GSP demonstrates that there is a significant correlation between groundwater levels and the other metrics. In order to rely on groundwater levels as a proxy, one approach suggested by DWR is to:

Demonstrate that the minimum thresholds and measurable objectives for chronic declines of groundwater levels are sufficiently protective to ensure significant and unreasonable occurrences of other sustainability indicators will be prevented. In other words, demonstrate that setting a groundwater level minimum threshold satisfies the minimum threshold requirements for not only chronic lowering of groundwater levels but other sustainability indicators at a given site (CA DWR, 2017).

Minimum thresholds for groundwater levels will effectively avoid undesirable results for reduction of groundwater storage. The ESJWRM Version 3.0 was run to estimate the reduction in groundwater storage that would occur if the chronic lowering of groundwater levels sustainability indicator undesirable result was triggered. The results of this analysis showed that this scenario would result in a reduction of approximately 10 to 13 MAF of storage.1 Because undesirable results as a result of lowering groundwater levels are anticipated to occur prior to a reduction of 23 MAF, the minimum thresholds for groundwater levels are protective of beneficial uses. Minimum thresholds and measurable 1 Volumes based on ESJWRM Version 3.0 estimates were calculated using multiple scenarios where five representative monitoring wells for groundwater levels reached their minimum thresholds across the Subbasin. Representative monitoring wells considered to exceed their minimum thresholds were selected based on proximity to the Subbasin’s groundwater depression, historical sustainable management criteria performance, and spatial distribution throughout the Subbasin.

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objectives for groundwater levels can therefore be used as a proxy for reduction in groundwater storage, as groundwater levels are sufficiently protective against occurrences of significant and unreasonable reduction in groundwater storage.

3.3.2.3 Measurable Objectives and Interim Milestones
As chronic lowering of groundwater levels is used as a proxy for reduction in groundwater storage, the measurable objectives and interim milestones for the reduction in groundwater storage sustainability indicator are the same measurable objectives and interim milestones as for the chronic lowering of groundwater levels sustainability indicator as set forth in Section 3.3.1.3.

3.3.3 Degraded Water Quality

3.3.3.1 Undesirable Results: Degraded Water Quality

3.3.3.1.1 Description of Undesirable Results
The undesirable result related to degraded water quality is defined in SGMA as:

Significant and unreasonable degraded water quality, including the migration of contaminant plumes that impair water supplies.

An undesirable result for degraded water quality in the Eastern San Joaquin Subbasin is experienced if SGMA-related groundwater management activities cause significant and unreasonable impacts to the long-term viability of domestic, agricultural, municipal, environmental, or other beneficial uses over the planning and implementation horizon of this GSP.

Salinity and chlorides (a component of salinity) are the only water quality constituents for which minimum thresholds are established in the Eastern San Joaquin Subbasin. High salinity in the western portion of the Subbasin has been an area of historical concern, as described in Section 2.2. There is potential for pumping to contribute to the movement of high saline water from the three sources noted by O’Leary et al. (2015): Sacramento-San Joaquin River Delta (Delta) sediments, deep deposits (called connate water), and irrigation return water (see Section 2.2.4.1). Other constituents, including arsenic and nitrate are evaluated in Section 2.2, with monitoring efforts described in Section 4.3. These constituents are managed through existing management and regulatory programs within the Subbasin, such as the Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) and the Irrigated Lands Regulatory Program (ILRP), which focus on improving water quality by managing septic and agricultural sources of salinity and nutrients. Additionally, point-source contaminants are managed and regulated through a variety of programs by the Regional Water Quality Control Board (RWQCB), Department of Toxic Substances Control (DTSC), and the U.S.

Environmental Protection Agency (EPA). Through new monitoring efforts, the GSP will document trends in these constituents and identify opportunities for coordination with existing programs. A description of existing regulations and requirements for these constituents is provided in Section 2.2.4. Through coordination with existing agencies and through additional monitoring, the ESJGWA will know if existing regulations are being met or groundwater pumping activities in the Subbasin are contributing to significant and unreasonable undesirable effects related to degraded water quality.

Total dissolved solids (TDS) was selected for the evaluation of sustainable management criteria for salinity under this sustainability indicator, as historical data for TDS are more widely available in the Eastern San Joaquin Subbasin than other constituents used to measure salinity, such as electrical conductivity (EC) or chloride. This decision was made by the ESJGWA Board based on the greater availability of TDS data in the Subbasin. TDS data are available through existing monitoring programs such as the CV-SALTS program and Groundwater Ambient Monitoring and Assessment (GAMA) Program or through monitoring or regulatory agencies such as United States Geological Survey (USGS), DWR, SWRCB, and the Central Valley Regional Water Quality Control Board (CVRWQCB) Waste Discharge Requirement (WDR) Dairy program. Additionally, GSA members and their affiliates including Cal Water, SJCFCWCD, EXHIBIT 1
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and the cities of Stockton, Lodi, and Manteca, provided TDS data from existing production wells. Chloride was also selected as a sustainability indicator for this sustainable management criterion. Chloride is a component (anion) of salinity and an indicator constituent of saltwater intrusion. Given the proximity of the Subbasin to the Delta, and the identification of Delta sediments as a potential source of salinity (O’Leary et. al, 2015), the use of chloride as an indicator of concern was deemed appropriate.

3.3.3.1.2 Identification of Undesirable Results
Undesirable results occur during GSP implementation when more than 25 percent of representative monitoring wells (3 of 10 sites) exceed the minimum thresholds for water quality for two consecutive years and where these concentrations are the result of groundwater management activities.

In addition to the monitoring of changes in groundwater elevations and the potential for those changes to result in undesirable results relative to groundwater quality, the ESJGWA and GSAs will collaborate and share data with other programs monitoring water quality data to observe both ambient and regulated conditions. Programs for coordination include, but are not limited to, the Irrigated Lands Regulatory Program (ILRP) and Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS), two existing regulatory programs for the monitoring and regulation of nitrate and salts. The ESJGWA, in coordination with the GSAs, will evaluate changes in groundwater quality on a bi-annual basis, in coordination with groundwater level monitoring, to determine if groundwater management has the potential to be a contributing factor to declines in groundwater quality. If so, the GSA(s) will coordinate with responsible regulatory agency(ies) to establish a plan to alleviate or prevent further degradation. Please see Appendix 3-F for additional information as to how the ESJGWA and Subbasin GSAs will coordinate to identify undesirable results and the potential causes of the decline in groundwater quality, and to develop and implement appropriate management actions to address that degradation.

3.3.3.1.3 Potential Causes of Undesirable Results
Elevated TDS concentrations in the Subbasin are the result of natural processes and overlying land use activities (O’Leary et al., 2015). Pumping in excess of recharge has resulted in declining aquifer water levels and led to an increase of salinity in groundwater wells since the 1950s (O’Leary et al., 2015). Within the Subbasin, there are localized concerns related to salinity along with three primary sources of salinity, as discussed in Section 2.2.4 of this GSP. To this end, potential mechanisms for causes of undesirable results include human-induced degradation and changes in water levels that may influence water quality, including:
• Falling groundwater levels which may cause migration of already-degraded groundwater from natural sources, nonpoint sources (salt, nitrate), or a plume from a point source. • Rising groundwater levels creating changes in oxidation potential and mobilization of arsenic. • Rising groundwater levels from recharge operations or reduced pumping that could mobilize nitrates or salts in the vadose zone.

3.3.3.1.4 Potential Effects of Undesirable Results
The potential effects of undesirable results related to degraded groundwater quality include reduction in usable supply of groundwater, increased treatment costs, and required access to alternate supplies, which can be unaffordable for small users. Some water quality issues could potentially cause more impact to agricultural uses than municipal or domestic uses depending on the impact of the constituent of concern to these water use sectors. Water quality degradation may cause potential changes in irrigation practices or crops grown, adverse effects to property values, and other economic effects.

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3.3.3.2 Minimum Thresholds
There are two constituents of concern for the Eastern San Joaquin Subbasin – Total Dissolved Solids (TDS) and chloride (representative of salinity). The minimum threshold for degraded water quality at all representative monitoring well locations is 1,000 milligrams per liter (mg/L) TDS, 250 mg/L chloride, or the groundwater concentration of those constituents as measured in 2015 at that representative monitoring location, whichever is greater. Figure 3-3 shows the representative monitoring locations for groundwater quality.

Minimum thresholds for this sustainability indicator are focused on addressing the major groundwater quality issue of salinity by monitoring TDS and chloride as representative constituents and preventing future water quality degradation due to pumping. Additional constituents, including nitrate and arsenic, will be monitored for informational purposes through the water quality monitoring network to identify trends and fill data gaps (see Section 0).

The ESJGWA Board selected a minimum threshold of 1,000 mg/L for TDS and 250 mg/L for chloride, or the constituent concentration as measured in 2015 (whichever is greater), based on stakeholder concerns for drinking water and agricultural beneficial uses. The minimum threshold reflects input from agricultural and municipal stakeholders, including local drinking water purveyors and the local agricultural community. A meeting was held in Fall 2018 with GSA representatives in areas impacted by high salinity. Representatives from San Joaquin County, City of Lodi, City of Manteca, City of Stockton, and Cal Water were in attendance. Additionally, members of the Workgroup who represent agribusiness interests provided input on the salinity levels at which crops begin to become impacted by salinity. Subsequent communications with Subbasin GSPs and outreach efforts conducted during the preparation of this Amended GSP have confirmed the same concerns regarding salinity concerns as in 2018.

During preparation of this Amended GSP, the inclusion of seawater intrusion as an applicable sustainability criterion was revisited. After further discussions, it was decided that seawater intrusion was not an appropriate sustainability criterion, but chloride was still a constituent of concern. As such, chloride was added as a constituent of concern to be addressed and managed through the groundwater quality sustainability indicator.

In the development of minimum thresholds, beneficial uses of groundwater as a drinking water supply and as an agricultural supply were considered. For drinking water, the secondary maximum contaminant levels (SMCLs)for TDS and chloride wereconsidered. As noted in Section 2.2, the SWRCB Division of Drinking Water (DDW) has established SMCLs forbothTDSand chloridein drinking water supplies. SMCLs are established for aesthetic reasons such as taste, odor, and color,and are not based on public health concerns. For TDS, the Recommended SMCL is 500 mg/L, anUpper Limit SMCL is 1,000 mg/L, a Short-Term limitis1,500 mg/L(SWRCB, 2017).For chloride, the SMCL is 250 mg/L. For agricultural uses, salinity tolerances of major Subbasin crops were considered. As previously stated in Section 1.2.1, dominant Subbasin crops are fruit and nut trees (primarily almonds, cherries, and walnuts), grapes, and alfalfa (USDA, 2015). Salinity tolerances for Subbasin crops range from 900 mg/L TDS (for almonds) to 4,000 mg/L TDS (for wheat) (Texas A&M AgriLife Extension, 2003, adapted from Ayers and Westcott, 1976; Hoffman, 2010).

Salinity tolerances of major Subbasin crops are shown in EXHIBIT 1
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Table 3-4. Because fruit and nut trees and vineyards collectively cover more than half of the acreage of the Subbasin, the minimum threshold was centered on the salinity impact of these crop types. These crop types have lower salinity tolerances, in the range of 900 to 1,000 mg/L TDS. Standards in this range are considered protective of these crop types and therefore the majority of Subbasin crops. TDS values are estimated based on applied irrigation water electrical conductivity values for a 90 percent crop yield potential (Texas A&M AgriLife Extension, 2003, adapted from Ayers and Westcott, 1976).

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Table 3-4: Salinity Tolerances of Major Subbasin Crops
Crop Type Salinity Tolerance
(mg/L TDS)
Fruit & Nut Trees - Almonds 900
Fruit & Nut Trees - Apples 1,000
Vineyards - Grapes 1,100
Alfalfa 1,400
Grain - Wheat 4,000
Field Crops - Corn 1,100
Truck Crops - Tomatoes 1,500
Rice 1,700
As the overall goal of the groundwater quality sustainable management criteria is to avoid worsening groundwater quality from 2015 conditions through basin management activities, the minimum thresholds for both TDS and chloride were set at the respective constituent’s SMCL (the Upper Limit for TDS) or 2015 groundwater quality concentration, whichever is greater, thereby acknowledging those portions of the Subbasin where degraded groundwater quality existed prior to 2015.

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Figure 3-3: Location of Representative Monitoring Wells for Water Quality Should an existing groundwater quality impairment or new groundwater quality impact be identified as having a direct impact on groundwater users, the ESJGWA and/or GSAs will coordinate with the appropriate regulatory agency(ies) to communicate the situation to those impacted, and will adaptively work with the regulatory agency(ies) to manage the situation. Additionally, the ESJGWA proposes the following program management actions for the Subbasin GSAs to be coordinated through the ESJGWA:

1. Regular Process for coordination
a. The ESJGWA will hold an annual “groundwater water quality state of the basin” meeting or workshop in January and invite the members of the San Joaquin County & Delta Water Quality Coalition (Coalition) to present the results of the monitoring program.
b. The ESJ Technical Advisory Committee (TAC) and Subbasin GSAs will invite participation and ex officio representation from the CVRWQCB staff to receive regular information regarding ILRP, CV-SALTS and any planned updates or amendments to the Central Valley Water Quality Control Plan (Basin Plan).

2. Monitoring
a. The ESJGWA will seek to develop monitoring and data sharing agreements with the Coalition.

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b. ESJGWA staff will work with the local Environmental Health Division and SWRCB Division of Drinking to identify drinking water wells which are nearing or have exceeded MCLs or SMCLs, noting the location, number of wells and the constituents of concern.

3. Data Management. Where possible, the ESJGWA will include the assessment of water quality data collected via other monitoring networks in their annual assessments and will use this information to further evaluate trends and any correlations between groundwater levels, the groundwater level MTs, and observed water quality conditions.

4. Annual Report. Beyond the reporting of data from the GSP groundwater level and water quality monitoring network, the ESJ Annual Report will include an expanded groundwater quality discussion to document:
a. The annual results of the Coalition’s monitoring program b. Known impairments identified by the CVRWQCB pursuant to the Basin Plan c. Wells and locations where MCLs have been exceeded as identified by the SWRCB Division of Drinking Water, consumer confidence reports, or the local Environmental Health Department

3.3.3.3 Measurable Objectives and Interim Milestones
At all representative monitoring well locations, the measurable objective (MO) for degraded water quality for TDS is 600 mg/L TDS. For chloride, the MO is the maximum recent historical measurement (as measured between 2015 and 2023). The TDS MO of 600 mg/L was developed based on the TDS recommended SMCL for drinking water of 500 mg/L with an added 100 mg/L buffer. A MO of 600 mg/L TDS is close to the recommended SMCL of 500 mg/L and significantly below the upper limit SMCL of 1,000 mg/L, and is considered adequate for drinking water and agricultural uses. The chloride MO was set equal to the maximum measured chloride concentration as measured during recent historical conditions (between 2015 and 2023), accounting for fluctuations in constituent concentrations with hydrologic conditions.

Interim milestones for 2025, 2030, and 2035 were developed to keep implementation on track to allow the Subbasin to meet the measurable objective for groundwater quality. Table 3-5 shows the 5-year milestones for TDS, which follow along a linear trend between the current condition (defined as the average TDS concentration between 2015 and 2023) and the measurable objective. Similarly,
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Table 3-6 shows the 5-year milestones for chloride, which follow along a linear trend between the current condition (defined as the average chloride concentration between 2015 and 2023) and the measurable objective. Interim milestones are based on the measurable objective and will be coordinated with projects and management actions. In two cases (for Well 16 and Well 17), current conditions were calculated by averaging TDS values collected from 2012- 2018. Additional detail on the RMN and SMC is included in Appendix 3-F.

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Table 3-5: Measurable Objective and Interim Milestones for Degraded Water Quality for Total Dissolved Solids (mg/L TDS)
Narrative Description
5-year milestones follow along a linear trend between the current condition (average TDS concentration between 2015 and 2023) and the measurable objective.

Numeric Interim Milestones
Well ID Average Chloride Measurable Objective Interim Milestones (2015 - 2023)* (mg/L chloride) 2025 2030 2035
Well 1 445 600 484 523 562
Well 2
(San Joaquin County)
568 600 576 584 592
Well 3 520 600 540 560 580
119-075-01 360 600 420 480 540
Well 15 310 600 383 456 529
Well 16
(City of Manteca)
250 600 338 426 514
Well 17 305 600 379 453 527
Stockton 27 65 600 199 333 467
Stockton SSS8 330 600 398 466 534
Stockton 31 301 600 376 451 526
Stockton 10R 390 600 443 496 549
Well No. 05 227 600 320 413 506
Well No. 07 173 600 280 387 494
Well #2
(Shady Rest Trailer Court)
323 600 392 461 530
WELL NO. 111 610 600 608 605 602
WELL NO. 161
(City of Ripon)
580 600 585 590 595
Swenson-3
2 NA 600 TBD TBD TBD
Lodi City Well #2 190 600 293 396 499
Hirschfeld (OID-8) 200 600 300 400 500
CCWD 010, 011, 0123 NA 600 TBD TBD TBD
NA – Not Available
* Current Condition is the average TDS value for 2015-2023. 1 No recent groundwater quality observations. Reported concentration from nearby WELL NO. 3. (CA3910007_003_003) from January 2015, January 2018, and January 2021.
2 Swenson-3 is currently not accessible, but since it is originally a GWL RMN, it is expected to be accessible going forward. If not, then another well will be selected to replace it. There are no recent groundwater quality observations from this well and the data reported in this table is from nearby well ID CA3910012_030_030 in October 1991. 3 No recent or nearby groundwater quality observations.

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Table 3-6: Measurable Objective and Interim Milestones for Degraded Water Quality for Chloride (mg/L chloride)
Narrative Description
5-year milestones follow along a linear trend between the current condition (average chloride concentration between 2015 and 2023) and the measurable objective.

Numeric Interim Milestones
Well ID Average Chloride Measurable Objective Interim Milestones (2015 - 2023)* (mg/L chloride) 2025 2030 2035
Well 1 34.6 36 35 35 35
Well 2
(San Joaquin County)
73 73 73 73 73
Well 3 34.6 36 35 35 35
119-075-01 26.6 30 27 28 29
Well 15 15.8 17 16 16 16
Well 16
(City of Manteca)

12.83 16 14 15 16
Well 17 15.2 17 16 16 16
Stockton 27 10.34 26 14 18 22
Stockton SSS8 38.5 41 39 40 41
Stockton 31 27.4 51 33 39 45
Stockton 10R 18 20 19 20 21
Well No. 05 14.7 17 15 16 17
Well No. 07 3.5 3.8 4 4 4
Well #2
(Shady Rest Trailer Court)

16.3 33 20 24 28
WELL NO. 111 75.5 83 77 79 81
WELL NO. 161
(City of Ripon)

75.5 83 77 79 81
Swenson-3
2 100 100 100 100 100
Lodi City Well #2 6.2 6.2 6 6 6
Hirschfeld (OID-8) 12 12 12 12 12
CCWD 010, 011, 0123 NA TBD TBD TBD TBD
NA – Not Available
* Current Condition is the average chloride value for 2015-2023. 1 No recent groundwater quality observations. Reported concentration from nearby WELL NO. 3. (CA3910007_003_003) from January 2015, January 2018, and January 2021.
2 Swenson-3 is currently not accessible, but since it is originally a GWL RMN, it is expected to be accessible going forward. If not, then another well will be selected to replace it. There are no recent groundwater quality observations and the reported data is from nearby well ID CA3910012_030_030 in October 1991.
3 No recent or nearby groundwater quality observations.

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3.3.3.4 Monitoring for Additional Constituents
Increased monitoring is needed to identify water quality trends related to additional constituents, including arsenic and nitrate. Arsenic, as well as cations and anions (which include nitrate), will be monitored for informational purposes through the water quality monitoring network (see Section 4.3.2) to identify trends and fill data gaps. Additionally, these constituents are currently regulated in the Subbasin through existing water resources monitoring and management programs, as described in Section 1.2.2. If water quality conditions violate those regulations, or if monitoring efforts indicate concerning trends, the ESJGWA will take steps to coordinate with regulatory agencies and will evaluate establishing minimum thresholds and measurable objectives for these constituents.

Many of the GSAs are drinking water suppliers and are required to provide a consumer confidence report each year.

The ESJGWA will consider requiring GSAs that are drinking water suppliers to notify the ESJGWA if constituents of concern exceed their maximum contaminant level (MCL) to assist in identifying potential trends of concern. While these reports do not reflect the water quality of private well owners, it would provide a basin-wide screen to inform basin groundwater quality conditions.

3.3.4 Seawater Intrusion
Seawater intrusion is not considered an applicable sustainability indicator for the Eastern San Joaquin Subbasin as the Subbasin is not in a coastal area and seawater intrusion is not currently present and is not reasonably expected to occur due to the active management of the ‘X2’ salinity barrier by the State (see Section 2.3.3). The ‘X2’ barrier, where the salinity is approximately 2 parts per thousand (ppt), is located well outside of the Subbasin boundary further downstream in the Delta (Cloern, 2012). (For reference purposes, the salinity of the ocean is about 35 ppt.) Various agencies and regulations, such as the Delta Protection Commission (DPC), Delta Stewardship Council, San Joaquin County & Delta Water Quality Coalition, and State Water Board Resolution No. 2009-011, contribute to managing and maintaining salinity conditions in the Delta region.

3.3.5 Land Subsidence

3.3.5.1 Undesirable Results

3.3.5.1.1 Description of Undesirable Results
The undesirable result related to land subsidence is defined in SGMA as:

Significant and unreasonable land subsidence that substantially interferes with surface land uses.

An undesirable result for land subsidence in the Eastern San Joaquin Subbasin is experienced if the occurrence of land subsidence substantially interferes with beneficial uses of groundwater and infrastructure within the Subbasin over the planning and implementation horizon of this GSP. Critical infrastructure in the Eastern San Joaquin Subbasin has been defined in coordination with the San Joaquin County Department of Public Works and the San Joaquin County Office of Emergency Services as the following infrastructure potentially at risk for interference from land subsidence:
• Major highways, roadways, and bridges
• Canals, pipelines, and levees
• Electrical transmission lines
• Schools
• Fire stations
• Hospitals and other medical facilities
• Law enforcement facilities (police stations, jails, correctional facilities) • Water and wastewater treatment, distribution, and storage facilities • Communication facilities
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The Subbasin is served by an extensive road network, including major interstate highways. The San Joaquin County Department of Public Works maintains the County’s 120-mile network of underground facilities, over 1,600 miles of roadway, 265 bridges, and 364 minor structures. In addition, San Joaquin County supports air service, a deep-water port, transcontinental rail, and commuter trains. Major roadways located within the Subbasin boundary include Interstate 5 (I-5) and multiple State Routes (4, 12, 26, 88, 99, 120). Major bridges in the Subbasin serve both automobile and railroad transport and include the San Joaquin River Bridge, Littlejohns Creek Bridge, Mormon Slough Bridge, and the Union Pacific Mossdale Bridge East.

Service buildings within the Subbasin include fire stations, hospitals, jails and correction facilities, police stations, and wastewater plants. The County also maintains 30 water systems with 52 wells, 3 sewage treatment plants, 9 sewage pumping stations, 68 storm drain pumping stations, and over 300 miles of levees and flood channels. In general, major pipelines that run through the County are in areas south of Lodi and southwest of Tracy along the foothills (outside of the Subbasin boundary).

In addition to identifying critical infrastructure at risk for subsidence impacts, the ESJGWA has worked with OES and the Subbasin GSAs to identify the total subsidence load that critical infrastructure in the Subbasin can tolerate during GSP implementation, and what would be considered an undesirable result. Through input from OES, the critical infrastructure in the Subbasin can generally tolerate a significant amount of uniform settlement due to subsidence across the Subbasin, though the total amount of settlement that can be tolerated is dependent on the design of the specific infrastructure. Differential settlement across facilities in a locale, on the other hand, will result in more damage.

However, it is worth noting that it is less common for subsidence to cause significant local differential sediment. In addition, the San Joaquin County 2017 Local Hazard Mitigation Plan identifies land subsidence as a potential cause for levee breakage; however, the hazard of subsidence is ranked “not likely” to occur. Through input from the Subbasin GSAs, local infrastructure can typically withstand subsidence ranging between 24 and 36 inches (San Joaquin County, 2017).

For the purposes of this Amended GSP, the major canals selected as critical infrastructure are the East Bay Municipal Utility District’s Mokelumne Aqueduct, stretching from the northeast to the western region of the Subbasin; Stockton East’s Mormon Slough and Stockton Diverting Canal in the central region; South San Joaquin Irrigation District’s Main District Canal in the southcentral region, and Oakdale Irrigation District’s North Main Canal in the southeastern corner of the Subbasin. The major roadways considered critical infrastructure include Highway 5 and Highway 99. Figure 3-4 illustrates all the critical infrastructure, including conveyance systems and major roads, across the Subbasin. Most of the minor canals are concentrated in the southern region of the Subbasin and are displayed for reference purposes only.

There are no historical records of significant and unreasonable impacts from subsidence in the Eastern San Joaquin Subbasin (see Figure 2-78). Per InSAR data currently available, 2015-2016 maximum subsidence rates in the Eastern San Joaquin Subbasin ranged from -1.2 inches per year (in/yr) to -2.4 in/yr, and there has been a maximum average subsidence rate of 0.93 in/yr over the last approximately 8 years (2015-2023). Given that approximately 10 years have lapsed since the implementation of SGMA commenced in 2015, and assuming an additional 10 years for achieving significant progress towards the Subbasin’s sustainability goal, it has been assumed that an additional 24 inches of subsidence (-1.2 in/yr times 20 years) can occur until 2040 without experiencing undesirable results relating to inelastic land subsidence. However, if land subsidence becomes an area of concern, the ESJGWA will take actions to understand the causes of the subsidence (including localized hydrogeology and groundwater pumping), consider improved monitoring protocols, and identify the next steps for addressing the potential for undesirable results.

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Figure 3-4: Defined Critical Infrastructure in the Eastern San Joaquin Subbasin

3.3.5.1.2 Identification of Undesirable Results
An undesirable result occurs when subsidence substantially interferes with the beneficial uses of groundwater and surface land uses. Subsidence, as it relates to groundwater use and management, occurs as a result of the compaction of subsurface materials due to the dewatering of fine-grained geologic materials, such as clay, leading to structural collapse and loss of void spaces. Undesirable results would occur when substantial interference with land use and critical infrastructure occurs (including significant damage to canals, pipes, or other water conveyance facilities) as a result of groundwater basin activities (such as pumping) and management.

Undesirable results related to inelastic land subsidence will be identified through data collected from the Subbasin’s representative monitoring network for inelastic land subsidence (using land subsidence data collection efforts conducted by individual GSAs, continuous global positioning system (CGPS) data collected and posted by the United States Geological Survey (USGS), and UNAVCO monitoring data collected and posted by UNAVCO’s Plate Boundary Observatory Program) supplemented with InSAR datasets collected and posted by DWR, and other publicly available datasets.

3.3.5.1.3 Potential Causes of Undesirable Results
Potential causes of future undesirable results for land subsidence would include significant increases in groundwater production beyond what is currently projected resulting in dewatering of compressible clays in the subsurface, which are not known to be common in the Eastern San Joaquin Subbasin, as indicated by historical absence of subsidence.

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Corcoran Clay is one type of subsurface material that is potentially predisposed to compression. See Section 2.1.5 for a description of Corcoran Clay extent in the Subbasin.

3.3.5.1.4 Potential Effects of Undesirable Results
If land subsidence conditions were to reach undesirable results, the adverse effects could potentially cause an irrecoverable loss of groundwater storage and damage to infrastructure, including water conveyance facilities and flood control facilities. This could impact the ability to deliver surface water, resulting in increased groundwater use, or could impact the ability to store and convey flood water. These could have adverse effects to property values or public safety.

3.3.5.2 Minimum Thresholds
The minimum threshold for land subsidence in the Subbasin is set at no more than 0.2 foot/year [2.4 inches/year] in any five-year period between 2020 and 2040, resulting in no more than a total additional 2 feet (24 inches) of land subsidence by 2040. This is set within the same magnitude of estimated error of the InSAR data (+/- 0.1 foot [0.03 m]), which is currently the most comprehensive tool available for measuring subbasin-wide land subsidence consistently each year, based on historical subsidence rates. The minimum threshold of 24 inches of additional subsidence by 2040 reflects the historical subsidence level with an added buffer, and is in line (both by method and magnitude) with the minimum thresholds established by other nearby basins overlying the Corcoran Clay.

The minimum thresholds selected for land subsidence for the Subbasin have been selected as a preventative measure to ensure the maintenance of current ground surface elevations and as an added safety measure for potential future impacts not presently occurring in the Subbasin and nearby basins. This avoids significant and unreasonable rates of land subsidence in the Subbasin, which are those that lead to a permanent subsidence of land surface elevations that impact infrastructure and agricultural production in the Subbasin and neighboring groundwater subbasins.

Given that the Subbasin is currently at the measurable objective (within the bounds of measurement error) and not expected to experience significant or unreasonable subsidence, it is not anticipated that the land subsidence minimum threshold will significantly affect any beneficial users of groundwater, land uses, or property interests. It is possible, should the current subsidence rates steepen, that there might be an impact to groundwater pumping (e.g., wells could be physically damaged, or conservation measures enacted). However, given the specific nature of the variable aquifer geology across the Subbasin, it would likely be confined to the southwestern portion of the Subbasin where a combination of groundwater overdraft and localized clay layers would operate together to display an inelastic subsidence signal. Nevertheless, neither of these cases are currently anticipated to coexist in the Subbasin at significant and unreasonable levels, especially with the development of projects and management actions that will achieve and maintain the Subbasin’s SMC for groundwater levels.

There are currently no other state, federal, or local standards that relate to this sustainability indicator in the Subbasin.

Additionally, in coordination with updates as described below for the 5-year interim milestones and as previously stated, as part of the Subbasin’s annual reporting process and to further supplement the land subsidence data collection efforts put forward in the GSP, CGPS data, InSAR data, and other subsidence data have been, and will continue to be, evaluated annually by the ESJGWA. These data will be compiled and evaluated each year as part of the data assessment and production of the Annual Report, submitted to DWR each year by April 1st. The current representative monitoring network for inelastic land subsidence is shown in Figure 3-5.

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Figure 3-5: Location of Representative Monitoring Sites for Subsidence

3.3.5.3 Measurable Objectives and Interim Milestones
The measurable objective for subsidence is based on the long-term avoidance of land subsidence: 0 ft/year, on a longterm average. This measurable objective is set recognizing the interconnectedness of the Subbasin with surrounding subbasins, and the ability to meet this objective is dependent on the successful management of all nearby subbasins.

Interim milestones are set in 5-year increments to provide time for the GSAs to adequately monitor for and, if necessary, address an issue that is technically complex, not well understood, and that has the potential to result in negative socioeconomic impacts depending on the ultimate solution. The interim milestones are defined as:
• 2025: -0.1 ft/year (1.2 in/yr)
• 2030: -0.05 ft/year (0.6 in/yr)
• 2035: -0.05 ft/year (0.6 in/yr)
• After 2040: 0 ft/yr (0 in/yr)
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The land subsidence interim milestone for 2025 was at a rate of -0.2 ft/year (2.4 in/year). This rate is higher than actual subsidence rates experienced throughout the Subbasin between 2015 and 2023 based on InSAR data available from DWR’s SGMA Data Viewer. The subsequent interim milestones have reduced subsidence values as projects and management actions are implemented to address groundwater levels and subsidence. These interim milestones are set recognizing that little active subsidence is currently occurring in the Eastern San Joaquin Subbasin, the interconnectedness of the Subbasin with surrounding subbasins (where subsidence may be occurring), and the ability to meet this objective is dependent on the successful management of all nearby subbasins.

3.3.6 Depletions of Interconnected Surface Water
Depletions of interconnected surface waters (ISWs) are defined as “conditions where groundwater pumping results in reductions in flow or water levels of ISW.” However, DWR’s guidance entitled Depletions of ISW: An Introduction (CA DWR, 2024) notes that “the definition above differs from how depletions may be defined in other hydrologic contexts, where they can refer to any surface water losses without considering the cause.” In acknowledging this, analyses were conducted using the ESJWRM model to evaluate stream losses to the aquifer system regardless of the cause, and to determine, based on the best available data and tools currently available, the timing, locations and magnitude of depletions that have occurred in the Subbasin or could occur in the future. These analyses are summarized in Appendix 3-G of this Amended GSP.

3.3.6.1 Undesirable Results

3.3.6.1.1 Description of Undesirable Results
The undesirable result related to depletions of interconnected surface water is defined in SGMA as:

Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water.

Major rivers and streams that potentially have a hydraulic connection to the groundwater system in certain reaches are the Calaveras River, Dry Creek, the Mokelumne River, the San Joaquin River, and the Stanislaus River. Many of the smaller creeks and streams in the Subbasin are substantially used for the conveyance of irrigation water, and these systems have not been considered in the analysis of depletions.

3.3.6.1.2 Identification of Undesirable Results
The undesirable result for depletions of interconnected surface water in the Eastern San Joaquin Subbasin is depletions that result in reductions in flow or levels of major rivers and streams that are hydrologically connected to the basin such that the reduced surface water flow or levels have a significant and unreasonable adverse impact on beneficial uses and users of the surface water within the Subbasin over the planning and implementation horizon of this GSP.

Beneficial uses and users were identified previously in Section 1.3.1.

3.3.6.1.3 Potential Causes of Undesirable Results
Potential causes of undesirable results would include increased regional groundwater extractions, reduced recharge due to drought, reduced availability of surface water supplies, and increased groundwater extraction along interconnected stream reaches.

3.3.6.1.4 Potential Effects of Undesirable Results
If depletions of interconnected surface water were to reach levels causing undesirable results, effects could include reduced flow and stage within rivers and streams in the Subbasin to the extent that insufficient surface water would be available to support diversions for agricultural or urban uses or to support regulatory environmental requirements.

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grown, and could cause adverse effects on property values and the regional economy. Reduced flows and stage, along with potential associated changes in water temperature and quality, could also negatively impact aquatic species and habitats in the rivers and streams and along the riparian environments. Such impacts are tied to the inability to meet minimum flow requirements, which are defined for the Mokelumne, Stanislaus, and San Joaquin Rivers, which, in turn, are managed through operations at Camanche Reservoir, Woodbridge Dam, New Melones Reservoir, and other reservoirs. It is important to note that the operations of upstream reservoirs are conducted by other entities, such as the U.S. Bureau of Reclamation, U.S. Army Corps of Engineers and East Bay Municipal Utilities District, and are outside the control of the Subbasin GSAs.

3.3.6.2 Minimum Thresholds
Minimum thresholds were established for ISW representative monitoring wells using groundwater levels as a metric.

Groundwater level data are used to calculate water table gradients and, therefore, the volume of water gained and lost.

Without additional DWR guidance at the time of this Amended GSP or more certainty around stream depletions due to pumping with the existing modeling toolset, the SMCs rely on the best available information at the time of analysis. The ISW SMCs using groundwater levels as a metric aim to be “sufficiently protective to ensure significant and unreasonable occurrences of [stream depletions] will be prevented,” as prescribed in the DWR’s Best Management Practices for the Sustainable Management of Groundwater: Sustainable Management Criteria (DWR, 2017).

The ESJ 2020 GSP and 2022 Revised GSP used groundwater level minimum thresholds as a proxy for the depletions of interconnected surface water sustainability indicator. This Amended GSP developed a representative monitoring network (RMN) specific for the interconnected surface water sustainability indicator consisting of a subset of wells from the chronic lowering of groundwater levels RMN combined with new wells constructed specifically to fill data gaps relating to an understanding of ISW. As such, some wells have a data set that allows for the setting of SMC, while others lack data because they are new.

The ISW minimum thresholds for wells with historical groundwater level observations are the same as for the chronic lowering of groundwater levels minimum thresholds. Analyses were conducted to demonstrate that the groundwater level minimum thresholds are protective of stream depletions and stream-aquifer interactions (stream connectivity, stream gains and losses, and stream gains and losses as a percentage of streamflow), and therefore the use of these minimum thresholds is justified. Descriptions of the analyses conducted and the associated results can be found in Appendix 3-G. Minimum thresholds will be established for new representative monitoring sites after at least four years of data have been collected, including data for at least one wet year and one dry or critical year during that time period.

If wet and dry/critical years do not occur during this initial period, then additional years of data collection may be required before establishing SMCs. Table 3-7 summarizes the minimum thresholds for the revised ISW representative monitoring network wells. Figure 3-6 shows the revised representative monitoring network for interconnected surface water.

Table 3-7: Minimum Thresholds for Interconnected Surface Water Well ID Minimum Threshold (ft msl)
Well A New well – need to collect data
Well B New well – need to collect data
Well C New well – need to collect data
Well E New well – need to collect data
Well G New well – need to collect data
Delta Well New well – need to collect data
04N05E36H003 -31.1
Swenson-3 -26.6
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Well ID Minimum Threshold (ft msl)
Frankenheimer (01S10E26J001M) 43.7
Burnett (OID-4) 60.8
02S07E31N001 0.8
02S08E08A001 0.6
Figure 3-6: Location of Representative Monitoring Sites for Interconnected Surface Water Establishing minimum thresholds for new monitoring wells requires data; as such, the minimum thresholds for recently constructed new monitoring wells and other new wells that may be constructed in the future will be established based on adjusted recent groundwater levels from a dry/critical year. The adjustment of groundwater levels is the difference in simulated groundwater levels in ESJWRM flow model between Water Year 2015 (a dry year) and the recent dry/critical year when groundwater level observations are measured. The calculation for the Minimum Threshold is:

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𝑀𝑖𝑛𝑖𝑚𝑢𝑚 𝑇ℎ𝑟𝑒𝑠ℎ𝑜𝑙𝑑
= 𝑂𝑏𝑠𝑒𝑟𝑣𝑒𝑑 𝑅𝑒𝑐𝑒𝑛𝑡 𝐷𝑟𝑦/𝐶𝑟𝑖𝑡𝑖𝑐𝑎𝑙 𝐺𝑊𝐿 − (𝑆𝑖𝑚𝑢𝑙𝑎𝑡𝑒𝑑 𝑅𝑒𝑐𝑒𝑛𝑡 𝐷𝑟𝑦 𝑌𝑒𝑎𝑟 𝐺𝑊𝐿𝑠 − 𝑆𝑖𝑚𝑢𝑙𝑎𝑡𝑒𝑑 2015 𝐺𝑊𝐿𝑠)
As a hypothetical example, suppose Water Year 2027 is a critical year and the observed groundwater elevation for Well C is 75 feet mean sea level (msl) in 2027. Assuming that the simulated groundwater elevations in ESJWRM at Well C increase by 8 feet between 2015 and 2027. The Minimum Threshold would be 75 feet minus 8 feet, or 67 feet msl.

3.3.6.3 Measurable Objectives and Interim Milestones
Similar to minimum thresholds, measurable objectives and interim milestones were established for ISW representative monitoring wells using groundwater levels as a metric, and as with the minimum thresholds for wells with historical groundwater level observations, the measurable objectives and interim milestones are the same as for the chronic lowering of groundwater levels measurable objectives and interim milestones. For new monitoring wells without historical groundwater level data, measurable objectives and interim milestones will be established for new representative monitoring sites after at least four years of data have been collected, including data for at least one wet year and one dry or critical year during that time period. If wet and dry/critical years do not occur during this initial period, then additional years of data collection may be required before establishing SMCs. Table 3-8 summarizes the measurable objectives and interim milestones for the revised ISW representative monitoring network wells.

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Table 3-8: Measurable Objectives and Interim Milestones for Interconnected Surface Water Interim Milestone (ft msl)
Well ID Measurable Objective
(ft msl) 2025 2030 2035
Well A New well – need to collect data
Well B New well – need to collect data
Well C New well – need to collect data
Well E New well – need to collect data
Well G New well – need to collect data
Delta Well New well – need to collect data
04N05E36H003 -5.1 -5.1 -5.1 -5.1
Swenson-3 -19.3 -19.3 -19.3 -19.3
Frankenheimer (01S10E26J001M) 81.7 81.7 81.7 81.7
Burnett (OID-4) 79.7 79.7 79.7 79.7
02S07E31N001 12.3 13.8 13.8 13.1
02S08E08A001 24 22.2 22.2 23.1
Establishing measurable objectives and interim milestones for new monitoring wells requires data; as such, the measurable objectives and interim milestones for recently constructed new monitoring wells and other new wells that may be constructed in the future will be established based after sufficient data have been collected. Measurable objectives will be established from an adjustment in groundwater levels from a wet year. The adjustment will add the difference in simulated groundwater levels from ESJWRM between Water Year 2011 (a wet year) and a recent wet year when groundwater level observations are collected. The calculation for Measurable Objectives is:

𝑀𝑒𝑎𝑠𝑢𝑟𝑎𝑏𝑙𝑒 𝑂𝑏𝑗𝑒𝑐𝑡𝑖𝑣𝑒𝑠
= 𝑂𝑏𝑠𝑒𝑟𝑣𝑒𝑑 𝑅𝑒𝑐𝑒𝑛𝑡 𝑊𝑒𝑡 𝐺𝑊𝐿 + (𝑆𝑖𝑚𝑢𝑙𝑎𝑡𝑒𝑑 𝑅𝑒𝑐𝑒𝑛𝑡 𝑊𝑒𝑡 𝑌𝑒𝑎𝑟 𝐺𝑊𝐿 − 𝑆𝑖𝑚𝑢𝑙𝑎𝑡𝑒𝑑 2011 𝐺𝑊𝐿𝑠)
As a hypothetical example, suppose Water Year 2026 is a wet year, and the observed groundwater elevation for Well C is 82 feet msl that year. Suppose that the simulated groundwater elevations in ESJWRM at Well C decrease by 15 feet between Water Year 2015 and 2026. The Measurable Objective would be 82 feet minus negative 15 feet, equaling 97 feet msl.

Interim milestones for recently constructed new monitoring wells and other new wells that may be constructed in the future will be calculated as 5-year milestones following a linear trend between the current condition (set as the period in time sufficient data have been collected) and the measurable objective for the time period remaining from the establishment of minimum thresholds and measurable objectives to 2040.

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4. MONITORING NETWORKS
Monitoring networks in the Eastern San Joaquin Subbasin are dedicated to monitoring short-term, seasonal, and long-term trends in sustainability indicators. There are four networks: two representative networks for water levels (one for the chronic lowering of groundwater levels sustainability indicator and one for the interconnected surface waters sustainability indicator), a representative network for groundwater quality, and a representative network for inelastic subsidence. These monitoring networks are tools for the Eastern San Joaquin Groundwater Authority (ESJGWA) and will allow the ESJGWA to compile data on key sustainability indicators and monitor groundwater trends on a variety of temporal and spatial scales. The objective of these monitoring networks is to detect undesirable results in the Subbasin as described in Chapter 3: Sustainable Management Criteria of this Groundwater Sustainability Plan (GSP). The data and trends will allow the ESJGWA to detect changes in Subbasin conditions, meet the Subbasin’s sustainability goal, avoid minimum thresholds, and evaluate the effectiveness of projects and management actions implemented.

Ultimately, the monitoring network and associated data will guide decisions to prevent undesirable results occurring within the GSP implementation timeframe. Other objectives of the monitoring networks, as defined by the Department of Water Resources (DWR), include:
• Demonstrate progress toward achieving measurable objectives described in the Plan • Monitor impacts to the beneficial uses or users of groundwater • Monitor changes in groundwater conditions relative to measurable objectives and minimum thresholds • Quantify annual changes in water budget components
The monitoring networks are intended to monitor for the chronic lowering of groundwater levels, degradation in groundwater quality, interconnected surface waters and inelastic subsidence. As discussed in Chapter 3: Sustainable Management Criteria, the reduction in groundwater storage sustainability indicator will be evaluated using groundwater levels as a proxy.

The schedule and costs associated with monitoring and implementation will be discussed in Chapter 7: Plan Implementation of the GSP.

4.1 MONITORING NETWORK FOR CHRONIC LOWERING OF GROUNDWATER LEVELS This section provides information on how the groundwater level monitoring network was developed, criteria for selecting dedicated monitoring wells, monitoring frequency, spatial density, and summary protocols. The monitoring network that collects data for groundwater levels is the Representative Monitoring Network (RMN). These wells will be used to monitor sustainability in the Subbasin. These wells are used to determine compliance with minimum thresholds and measurable objectives for the groundwater level sustainability indicator.

4.1.1 Representative Monitoring Network for Groundwater Levels Representative monitoring wells represent overall conditions in the production zone in the Subbasin and are reflective of regional groundwater conditions in the vicinity. Table 4-1 identifies and summarizes the 23 representative monitoring wells for groundwater levels. Well locations were shown previously in Figure 3-2 in Chapter 3: Sustainable Management Criteria.

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Table 4-1: Representative Monitoring Wells for Groundwater Levels Local Well ID CASGEM Site Code Well
Location
Well
Depth
(ft.)
Screen
Interval
in ft. bgs
(ft. MSL)
Measurement
Period
(years)
Measurement
Count
Swenson-3 380067N1213458W003 San
Joaquin
County
(SJC)
204 194–204
(-190 to -
200)
2014–2018 20
01S09E05H002 378824N1210000W001 SJC 256 148–256
(-41 to -
149)
1991–2018 7
Burnett (OID4) 377909N1208675W001 Stanislaus
County
501 168–249
(21 to -60)
2005–2019 3
02N07E03D001 380578N1212017W001 SJC 484 130–484
(-74 to -
428)
1990–2018 1
04N07E20H003M 381843N1212261W001 SJC 180 164–180
(-87to -
103)
1972–2019 111
02S07E31N001 377136N1212508W001 SJC Unknown Unknown 1991–2018 14 02S08E08A001 377810N1211142W001 SJC 180 50–180
(22 to -
108)
1991–2018 8
01N07E14J002 379316N1211665W001 SJC 556 168–556
(-116 to -
504)
1991–2018 12
01N09E05J001 379661N1210011W001 SJC 750 100–750
(56 to -
594)
2011–2018 13
02N07E29B001 379976N1212308W001 SJC 202 130–202
(-88 to -
160)
1989–2018 2
02N08E15M002 380206N1210943W001 SJC Unknown Unknown 2011–2013 2 03N07E21L003 380909N1212153W001 SJC Unknown Unknown 1991–2013 15 03N06E05N003 381317N1213524W001 SJC 292 252–292
(-225 to -
265)
1991–2018 16
04N05E36H003 381559N1213727W001 SJC 112 50–112
(-27 to -
89)
1971–2018 4
04N05E24J004 381816N1213723W001 SJC 190 150–190
(-128 to -
168)
1991–2018 9
#3 Bear Creek Not Part of CASGEM
Program
Lockeford
Community
Services
District
(LCSD)
780 0–780
(96 to -
684)
2011–2018 18
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Local Well ID CASGEM Site Code Well
Location
Well
Depth
(ft.)
Screen
Interval
in ft. bgs
(ft. MSL)
Measurement
Period
(years)
Measurement
Count
Lodi City Well #2 Not Part of CASGEM
Program
City of Lodi 315 109–310
(-57 to -
258)
1927–2015 17
Hirschfeld (OID8) Not Part of CASGEM
Program
Stanislaus
County
408 88–179
(44 to -47)
2005–2016 19
Well 18 Not Part of CASGEM
Program
City of
Manteca
350 109–349
(-65 to -
305)
1997–2018 5
Frankenheimer
(01S10E26J001M)
378163N1208321W001 Stanislaus
County
Unknown 10
01S10E04C001M 378846N1208816W001 Stanislaus
County
NSJWCD-01
382345N1212261W001
- 06
NSJWCD 1.215 Multiple
165-1,200
NA 0
SEWD-01 379794N1211083W001
- 05
SEWD 1,650 Multiple
190-1,635
NA 0
Representative groundwater level sites were selected by several different criteria. These include:

1. Adequate Spatial Distribution – Representative monitoring does not require the use of all wells that are spatially “clumped” together within a portion of the Subbasin. Adequately spaced wells will provide sufficient coverage with fewer monitoring sites.

2. Robust and Extensive Historical Data – Representative monitoring sites with a longer period of record and a greater number of historical measurements will provide insight into long-term trends that can provide information about groundwater conditions through varying climatic periods such as droughts and wet periods.

Historical data may also show changes in groundwater conditions through anthropogenic effects as well. While some sites chosen may not have extensive historical data, they may still be selected because there are no wells nearby with longer records.

3. Increased Density in Heavily Pumped Areas – Selection of additional wells in heavily pumped areas such as in the central portion of the Subbasin and other agriculturally intensive areas will provide additional data where the most groundwater change may occur.

4. Increased Density near Areas of Geologic or Hydrologic Uncertainty – Having a greater density of representative wells in areas of uncertainty, such as around faults or large elevation gradients, may provide insight into groundwater dynamics to improve management practices and strategies.

5. Wells with Multiple Depths – The utilization of wells with different screen intervals is important to collect data on the groundwater conditions at different elevations within the aquifer. This can be achieved by using wells with different screen depths that are close to one another, or by using multi-completion wells.

6. Consistency with BMPs – Using published Best Management Practices (BMPs) provided by DWR will promote consistency across subbasins and promote compliance with established regulations.

7. Adequate Well Construction Information – Well information such as perforation depths, construction date, and well depth was considered and encouraged when considering wells to be included.

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8. Professional Judgement – Professional judgement is used to make the final decision about each well, particularly when more than one suitable well exists in an area of interest.

9. Maximum Coverage – Monitoring network wells were selected to prioritize spatial and vertical density of monitoring.

Figure 4-1 shows the revised representative monitoring network for groundwater levels.

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Figure 4-1: Representative Monitoring Network for Groundwater Levels

4.1.2 Monitoring Protocols for Groundwater Level Data Collection and Monitoring Groundwater monitoring protocols are essential to producing quality data measurements and protecting the water quality of monitoring wells. Existing protocol resources include DWR’s Groundwater Elevation Monitoring Guidelines (CA DWR, 2010) and USGS’s National Field Manual for the Collection of Water Quality Data (USGS, var.). Protocols are established to improve consistency in data and ensure comparable methodologies.

Typical groundwater level measurement equipment used by agencies includes electric sounders, data loggers, steel tapes, and air gauges. Regardless of the instrumentation used in the field, each groundwater level data measurement must include: well identification number, measurement date, reference point and land surface elevation, depth to water, method of measuring water depth, measurement quality codes, any observations on well conditions (i.e., condition of surface seal, accessibility issues, obstructions within the wells, etc.), and measurement to the base of the well (total well depth).

DWR released a BMP for monitoring protocols, in the Best Management Practices for the Sustainable Management of Groundwater Monitoring Protocols, Standards, and Sites (CA DWR, 2016a). The monitoring protocols described in DWR’s BMP recommend that groundwater level measurements are taken in a manner to ensure data are:

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• Taken from the correct location, well ID, and screen interval depth • Accurate and reproducible
• Representative of conditions that inform appropriate basin management data quality objectives • Recorded with all salient information to correct, if necessary, and compare data • Handled in a way that ensures data integrity.
• Taken using a CASGEM-approved water-level measurement method to ensure consistency across measurements. Methods include:
o Establishing a reference point
o Using one of four approved methods (steel tape, electric sounding tape, sonic water-level meter, or pressure transducer) to measure groundwater levels
Existing wells, monitored under the CASGEM program, already use these procedures in the collection of groundwater level data. The protocols used for CASGEM groundwater level monitoring will be used when possible in data monitoring and collection in support of this GSP.

4.1.3 Frequency and Timing of Groundwater Level Monitoring Representative monitoring network wells for groundwater levels will be monitored semi-annually in March and October to capture the seasonal high and low groundwater levels and to avoid interference from pumping wells during irrigation season.

Frequency of groundwater level monitoring is cited in the Draft Monitoring Networks and Identification of Data Gaps Best Management Practice (CA DWR, 2016b) which presents guidance on monitoring frequency based on the type of monitoring, aquifer type, confinement, recharge rate, hydraulic conductivity, and withdrawal rate. While semi-annual monitoring is required for groundwater levels, DWR guidance recommends monthly sampling of groundwater levels for the Eastern San Joaquin Subbasin based on aquifer type, volume of long-term aquifer withdrawals, and recharge potential. Sampling frequencies were developed based on this guidance in combination with a consideration of sampling costs.

A semi-annual monitoring frequency will generate data that is useful for monitoring for the long term, regional trends in groundwater level conditions. These measurements are also valuable for local groundwater management and for investigating local pumping’s effects on nearby wells. This frequency meets the goal of a successful monitoring schedule which provides enough data to adequately interpret changes in groundwater levels and fluctuations over short- and long-term periods, as these fluctuations could be the result of storm events, droughts, or other climatic variations, seasons, and anthropogenic activities.

4.1.4 Spatial Density of Groundwater Level Monitoring Network The goal of the groundwater level monitoring network is to provide adequate spatial coverage within the Subbasin.

This includes the ability to monitor and identify groundwater changes across the Subbasin through time. The spatial location of monitoring wells in the networks was based on proximity to other monitoring wells and ensuring adequate coverage near other prominent features such as faults or production wells. Monitoring wells in close proximity to active pumping wells could be influenced by groundwater withdrawals, thus skewing static level monitoring.

To achieve a suitable monitoring network density, DWR recommends selecting existing, dedicated groundwater monitoring wells with known construction information over production wells to incorporate into the network. When deciding on the number of groundwater wells to be monitored in a basin to adequately represent static water levels (and corresponding elevations), the following factors should be considered:

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• Known hydrogeology of the basin
• Slope of the groundwater table or potentiometric surface • Existence of high-volume production wells and the frequency of their use • Availability of easily accessible monitoring wells
In 2010, DWR released Groundwater Elevation Monitoring Guidelines, which discusses the selection and requirements for new wells to be incorporated into groundwater level monitoring networks (CA DWR, 2010). The recommended network density ranges from 0.2 to 10 groundwater monitoring wells per 100 square miles depending on local pumping rates. The Subbasin is approximately 1,195 square miles. Based on the recommendations by DWR, the number of monitoring wells for the Eastern San Joaquin Subbasin should range from 2.4 to 119.5 wells per 100 square miles, as summarized in Table 4-2.

Table 4-2: DWR Monitoring Well Density Recommendations
Reference Monitoring Well Density
(wells per 100 sq. miles)
Recommended No. of
Monitoring Wells in the
Subbasin
Heath (1976) 0.2 – 10 2.4 – 119.5
Sophocleous (1983) 6.3 75.9
Hopkins (1994)
Basins pumping more than 10,000 AF/year per
100 miles 4.0 47.8
The spatial density of the groundwater level monitoring network was calculated for the representative monitoring network, as summarized in Table 4-3. The density of the representative monitoring network is 1.7 wells per 100 square miles, a total of 23 monitoring wells, which falls into the lower to middle range of DWR’s recommendations. However, the Subbasin is continuing to work to expand its representative monitoring network and to construct additional wells to address identified data gaps.

Table 4-3: Groundwater Level Monitoring Network Density Monitoring Network No. of Wells Well Density
(Wells per 100 sq. miles)
Representative Monitoring
Network 23 1.7

4.2 MONITORING NETWORK FOR REDUCTION IN GROUNDWATER STORAGE Groundwater levels will be used as a proxy for the reduction in groundwater storage sustainability indicator as described in Chapter 3: Sustainable Management Criteria. Sustainable management criteria for groundwater storage will be monitored through the groundwater levels monitoring networks, described in Section 4.1. Monitoring data collected by the groundwater level monitoring networks will support future characterization of groundwater in storage.

4.3 MONITORING NETWORKS FOR DEGRADED WATER QUALITY
Groundwater quality monitoring is conducted through a representative groundwater well monitoring network specific for this sustainability indicator. This section provides information on how the monitoring network was developed, criteria for selecting dedicated monitoring wells, monitoring frequency, spatial density, and summary protocols.

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The representative monitoring network for groundwater quality is used to determine compliance with minimum thresholds and measurable objectives developed for the degraded water quality sustainability indicator. The network monitoring for water quality tests for total dissolved solids (TDS) and chloride, in addition to field parameters including pH, electrical conductivity (EC), and temperature. Other groundwater quality data are collected from publicly available sources and other ongoing monitoring programs (such as the Irrigated Lands Program) and evaluated for arsenic, nitrate, and other constituents of concern for informational purposes. The GSP does not include sustainability goals, measurable objectives, or minimum thresholds for these other constituents.

4.3.1 Representative Monitoring Network for Groundwater Quality Twenty-one representative monitoring wells were selected for monitoring groundwater quality. These wells are currently monitored and managed by City of Manteca, Cal Water, City of Stockton, and San Joaquin County.

Table 4-4 identifies and summarizes the agencies with the 21 representative monitoring wells selected for the groundwater quality monitoring network, which is shown in Figure 4-2.

Figure 4-2: Representative Monitoring Network for Groundwater Quality EXHIBIT 1
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Table 4-4: Representative Monitoring Network Wells for Water Quality GSP Well ID CASGEM ID GM Well ID Monitoring Agency Latitude Longitude Source Screen Group Screen
Top (feet
bgs)
Screen
Bottom
(feet bgs)
Well
Depth
(feet
bgs)
Well 1 381154N1213818W001 CA3901248_001_001 San Joaquin County (Flag City) 38.115366 -121.381755 2020 RMW Shallow (less than 200') 110 170 - Well 2 381131N1213920W001 CA3901248_002_002 San Joaquin County (Flag City) 38.113064 -121.391997 2020 RMW Shallow (less than 200') 110 170 - Well 3 381130N1213887W001 San Joaquin County (Flag City) 38.11299 -121.388682 2020 RMW Unknown - - - 119-075-01 01N/07E-18D01M CA3910001_063_063 Cal Water 37.980357 -121.263022 2020 RMW Deep (greater than 200') 200 560 - Well 15 378089N1212325W001 CA3910005_015_015 City of Manteca 37.808954 -121.232674 2020 RMW Both 140 240 - Well 16 377904N1212476W001 CA3910005_016_016 City of Manteca 37.790339 -121.247724 2020 RMW Both 137 274 - Well 17 378059N1211878W001 CA3910005_028_028 City of Manteca 37.805695 -121.18896 2020 RMW Both 110 230 - Stockton 27 City of Stockton 37.994542 -121.282878 2023 AR Shallow (less than 200') 0 200 - Stockton SSS8 379146N1212401W001 CA3910012_089_089 City of Stockton 37.91465 -121.237343 2020 RMW Both 158 256 - Stockton 31 CA3910012_094_094 City of Stockton 38.045846 -121.263778 2023 AR Both1 157 362 380 Stockton 10R 380292N1212843W001 CA3910012_100_100 City of Stockton 38.028706 -121.285004 2020 RMW Both2 164 488 498 Well No. 05 CA3910008_005_005 Lockeford CSD 38.155478 -121.150908 New CA7 Deep (greater than 200') 250 310 - Well No. 07 CA3910019_007_007 Linden County WD 38.025715 -121.088695 New CA7 Deep (greater than 200') 480 600 - Well #2 CA3900755_002_002 Shady Rest Trailer Court 37.994757 -121.171349 New CA7 Deep (greater than 200') 200 210 - WELL NO. 11 CA3910007_012_012 City of Ripon 37.729054 -121.141496 New CA7 Shallow (less than 200') 125 155 163 WELL NO. 16 CA3910007_026_026 City of Ripon 37.7510854 -121.1264178 New CA7 Deep (greater than 200') 232 356 366 Swenson-3 380067N1213458W003 38.0067 -121.3458 GWL RMN Multiple Wells3 194 502 Lodi City Well #2 CA3910004_003_003 City of Lodi 38.1376 -121.274 GWL RMN Both 110 309 - Hirschfeld (OID-8) Oakdale ID 37.8352 -120.957 GWL RMN Deep (greater than 200') - - 408 CCWD 010, 011, 012 Calaveras County WD 38.16278308 -120.92918 Former Broad Monitoring Network Multiple Wells4 115 390 1 Screened: 157-172, 183-207, 308-328, 337-362 feet deep 2 Screened: 164-172, 180-194, 208-266, 294-306, 358-412, 452-466, 474-488 feet deep 3 Screened 1: 482-502, 2: 294-314; 3:194-204 feet deep
4 Screened 010: 370-390; 011: 250-270; 012: 115-135 feet deep EXHIBIT 1
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Representative monitoring wells were selected based on their ability to represent conditions in the Subbasin and indicate long-term, regional changes in groundwater quality conditions. Groundwater Sustainability Agencies (GSAs) in areas affected by high TDS and chloride levels identified wells to be used as representative monitoring wells that met the following criteria:

1. Adequate Spatial Distribution – High TDS and/or chloride concentrations historically have occurred in the western portion of the Subbasin, near the San Joaquin River and urban areas; as such, the majority of representative monitoring wells are located in the western half of the Subbasin. Monitoring wells are located both within areas of high TDS and/or chloride concentrations, to observe and monitor TDS and/or chloride trends, and adjacent to high TDS and/or chloride areas, to observe potential TDS and/or chloride movement.

2. Extensive Historical Data – Wells with longer records of TDS and/or chloride monitoring were preferentially selected over wells with short or sporadic records. Monitoring wells with historical TDS and/or chloride records provide insight on long-term trends and the groundwater condition responses to varying climatic periods such as droughts and wet periods and/or anthropogenic effects.

3. A Range of TDS Concentrations – Wells with historically low TDS and/or chloride concentrations near areas with high salinity were looked at to alert a change in groundwater quality conditions and a possible migration of salinity.

4. Known Well Construction Information – Wells with known construction data, including total depth, screen intervals, and construction date, were preferred. Knowledge of the depth at which water quality measurements are taken would better describe the representative conditions of specific portions of the aquifer.

5. Current TDS Monitoring Program – Wells currently monitored for TDS and/or chloride were preferred over wells not currently monitored for water quality constituents. These wells are already equipped for monitoring and have existing protocols to ensure accurate and consistent measurements, and they represent a current asset for the Subbasin that can be further utilized.

6. Consistency with BMPs – DWR’s published BMPs were used as guidance documents to ensure consistency across all basins and ensure compliance with established regulations.

7. Professional Judgement – Professional judgement was used to make the final decision about each well, particularly when more than one suitable well exists in an area of interest.

4.3.2 Monitoring Protocols for Groundwater Quality Data Collection and Monitoring Groundwater quality data sampling protocols are based on DWR’s Best Management Practices for the Sustainable Management of Groundwater Monitoring Protocols, Standards, and Sites (CA DWR, 2016a), which cites the USGS’s 1995 publication Ground-Water Data-Collection Protocols and Procedures for the National Water-Quality Assessment Program: Collection and Documentation of Water-Quality Samples and Related Data (USGS, 1995). The BMP recommends groundwater quality monitoring protocols and also recommends using the USGS National Field Manual for the Collection of Water Quality Data (USGS, var.) for additional protocols. These publications include protocols for equipment selection, setup, use, field evaluation, sample collection techniques, sample handling, and sample testing.

Groundwater quality sampling protocols recommended in the BMP include ensuring that:
• Groundwater quality data are taken from the correct location • Groundwater quality data are accurate and reproducible • Data represents conditions that inform appropriate basin management and are consistent with the data quality objectives
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• Data are handled in a way that ensures data integrity • All salient information is recorded to normalize, if necessary, and compare data As a quality assurance measure, an operating standard will be developed to ensure data integrity. See Chapter 7: Plan Implementation for additional information on monitoring plan implementation.

4.3.3 Frequency and Timing of Groundwater Quality Monitoring Groundwater quality measurements will be collected semi-annually from the representative monitoring network wells.

Although DWR does not provide specific recommendations on the frequency of monitoring for TDS and/or chloride, concentrations of groundwater quality, especially salinity, do not typically fluctuate significantly throughout a year to require multiple samples per year. No existing monitoring wells were found to be monitored continuously for groundwater quality (such monitoring is typically performed only for EC and temperature), nor were there agencies that reported ongoing, non-regulatory, regularly scheduled groundwater quality monitoring programs. Table 4-5 identifies the historical frequency of groundwater quality monitoring conducted for local water quality wells by each monitoring agency.

Table 4-5: Historical Groundwater Quality Monitoring Frequency at Identified Local Water Quality Wells
Agency Data Record Historical Monitoring
Frequency (Approx.)
Cal Water 1979 - 2018 Approx. every 3 years
City of Lodi 2008 - 2018 Approx. every 3 years
City of Manteca 1975 - 2017 Monthly
City of Stockton 1989 - 2016 Quarterly
San Joaquin County – Flag City 2009 - 2017 Annually

4.3.4 Spatial Density of Groundwater Quality Monitoring Wells DWR’s Monitoring Networks and Identification of Data Gaps BMP states “The spatial distribution must be adequate to map or supplement mapping of known contaminants” (CA DWR, 2016b). The goal of the groundwater quality monitoring network is to adequately cover the Subbasin to accurately characterize salinity concentrations and trends.

This includes both spatial coverage and temporal coverage in order to identify changes in groundwater quality over time.

DWR’s Monitoring Networks and Identification of Data Gaps BMP identifies different sources and calculations for establishing monitoring network densities on a Subbasin-specific case (CA DWR, 2016b). These density calculations and guidance are summarized in Table 4-2. The spatial density of the groundwater quality monitoring network was calculated for the representative monitoring network, as summarized in Table 4-6. The representative monitoring network consists of a total of 21 monitoring wells, a density of 1.2 wells per 100 square miles.

Table 4-6: Groundwater Quality Monitoring Network Density Monitoring Network No. of Wells Well Density (Wells per 100 sq. miles)
Representative Monitoring Network 21 1.2

4.4 MONITORING NETWORK FOR SEAWATER INTRUSION
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Seawater intrusion is not considered an applicable sustainability indicator for the Eastern San Joaquin Subbasin.

4.5 MONITORING NETWORK FOR LAND SUBSIDENCE
Monitoring for inelastic land subsidence is conducted through a representative monitoring network specific for this sustainability indicator. This section provides information on how the monitoring network was developed, criteria for selecting dedicated monitoring locations, monitoring frequency, spatial density, and summary protocols.

The representative monitoring locations for inelastic land subsidence monitoring were selected from existing subsidence datasets and monitoring locations, including CGPS vertical displacement data from the DWR Sustainable Groundwater Management Act (SGMA) Data Viewer, InSAR subsidence rates from the SGMA Data Viewer, and survey benchmarks from U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), California Department of Transportation (CalTrans), the San Joaquin County Department of Public Works, and local agencies. There are no DWR or USGS extensometers in the Eastern San Joaquin Subbasin.

4.5.1 Representative Monitoring Network for Subsidence
Four CGPS stations were selected for the Subbasin’s representative monitoring network for inelastic land subsidence based on data availability, location, and monitoring status. The first station, P309 (SOPAC), is located in the eastern region of the Subbasin, north of the Calaveras River, and provides a comprehensive data record from March 4, 2006, to January 19, 2024. This station was chosen due to its extensive data period and its spatial coverage in the eastern portion of the Subbasin. The second station, MTWK (UNAVCO), is situated in the southern region of the Subbasin, south of the city of Manteca, with data available from December 12, 2019, to January 19, 2024. It is the closest station to the Corcoran clay, an important area to monitor due to the potential for inelastic subsidence near clay-rich areas.

Additionally, two stations from the University of Nevada Geodetic Laboratory (UNGL) were included in the RMN to provide further spatial coverage and address data gaps. The CMNC station, located along the southern edge of the Camanche Reservoir, has data in 2020 and between February 2022 and January 2024. The CA1S station, north of the city of Stockton, offers a continuous record from October 2021 to September 2023. These stations were selected to enhance the spatial distribution of monitoring locations and continuity of subsidence data in the Subbasin.

Six survey benchmarks from San Joaquin County and National Geodetic Survey (NGS) were selected to supplement the CGPS data. Survey benchmarks were also selected to expand the spatial coverage of the subsidence monitoring network in the Subbasin and verify to InSAR data. From San Joaquin County, survey benchmarks M-20 and O-29 were selected. Benchmark M-20 was chosen for the RMN due to its location in the Subbasin, situated in the area with the highest subsidence rate. Benchmark O-29 was selected for its position near a localized, unverified point location of increased subsidence according to InSAR data.

From the NGS, benchmarks Q-833, J-956, G-965, and J-957 were selected. Benchmark Q-833 was chosen due to its proximity to the LODI CGPS Station, its good condition, and elevation observations in 1947 and 1987. Benchmark J956 is an important survey benchmark because it was recently surveyed in 2024, is in good condition, and is located in the cone of depression area with higher subsidence rates. Benchmark G-965 was selected for the RMN because of its good condition, long period of record dating back to 1962, and its location in the cone of depression area, with the latest survey in 1987. Benchmark J-957 was chosen for its observations in 1962 and 1987, its good condition, and its location in the southeast corner of the Subbasin. InSAR will serve as a supplementary data source for the rest of the Subbasin, and its accuracy will be validated using CGPS and benchmark data.

Table 4-7 describes monitoring site type, location, and data source for the four CGPS Stations and six survey benchmarks that will make up the Subbasin’s RMN for the inelastic land subsidence sustainability indicator. Figure 4-3 shows the selected representative monitoring locations across the Subbasin.

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Table 4-7: Representative Monitoring Network for Inelastic Land Subsidence Name Type Location (dd) Source
CA1S CGPS Lat: 38.022 N
Long: 121.324 W
UNGL
CMNC CGPS Lat: 38.206 N
Long: 120.999 W
UNGL
MTWK CGPS Lat: 37.778 N
Long: 121.185 W
UNAVCO
P309 CGPS Lat: 38.089 N
Long: 120.951 W
SOPAC
Q-833 Survey Benchmark Lat: 38.130 N
Long: 121.272 W
NGS
J-956 Survey Benchmark Lat: 38.043 N
Long: 121.139 W
NGS
G-965 Survey Benchmark Lat: 38.003 N
Long: 121.139 W
NGS
M-20 Survey Benchmark Lat: 38.014 N
Long: 121.139 W
San Joaquin County
O-29.6 Survey Benchmark Lat: 37.875 N
Long: 121.183 W
San Joaquin County
J-957 Survey Benchmark Lat: 37.856 N
Long: 120.998 W NGS
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Figure 4-3: Representative Monitoring Network for Inelastic Land Subsidence

4.5.2 Monitoring Protocols for Subsidence Data Collection and Monitoring Monitoring for inelastic land subsidence will occur semi-annually for survey benchmarks. Standard practices and protocols for land surveying as set forth in the Caltrans Surveys Manual (California Department of Transportation, 2021) will be followed to measure land surface elevations at those locations. Measurements will be in the same vertical datum, preferably NAVD88. CGPS data will be downloaded from the online data sources referenced in Section 4.5.1.

InSAR data will be sourced annually from DWR’s SGMA Data Viewer and compared against the land-based measurements as a quality control check.

4.5.3 Frequency and Timing of Subsidence Monitoring
As noted in Section 4.5.2, land surface elevations will be surveyed semi-annually in the spring and fall at the benchmarks noted in Table 4-7. Data for all other representative monitoring locations will be sourced from online published data in coordination with preparation of the Subbasin’s Annual Report.

4.5.4 Spatial Density of Subsidence Monitoring Stations Per DWR’s Best Management Practices for the Sustainable Management of Groundwater, Monitoring Protocols, Standards, and Sites (2016a), the representative monitoring locations for inelastic land subsidence in the Subbasin was established to monitor regions where the potential for subsidence exists. As such, the monitoring locations were EXHIBIT 1
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selected to provide an overall network of sites for data collection that represent the different areas of the Subbasin – areas upland, near the Delta, overlying the Corcoran clay and overlying unconfined alluvial systems. While the representative monitoring network contains discrete data collection locations, the use of InSAR survey data in the annual evaluation for the potential for subsidence provides Subbasin-wide coverage in coordinate with the direct data measurements.

4.6 MONITORING NETWORK FOR DEPLETIONS OF INTERCONNECTED SURFACE WATERS This section provides information on how the monitoring network was developed for interconnected surface water (ISW), criteria for selecting dedicated monitoring wells, monitoring frequency, spatial density, and summary protocols.

Like the wells used to monitor groundwater levels to assess sustainability in the Subbasin, these wells are used to determine compliance with minimum thresholds and measurable objectives for the interconnected surface water sustainability indicator.

4.6.1 Representative Monitoring Network for Interconnected Surface Water The representative monitoring wells contained in the network for interconnected surface water consists of a subset of the groundwater level (GWL) RMN wells that are within five miles of connected surface waters plus six newly constructed monitoring wells constructed in 2022 and 2024 to address data gaps. Only one well (the shallowest well in a gap area) was selected from the GWL RMN along the Mokelumne River since there are the new ISW wells along other sections of the Mokelumne River. Table 4-8 identifies and summarizes the 12 representative monitoring wells for interconnected surface waters.

Table 4-8: Representative Monitoring Wells for Interconnected Surface Water Well ID Latitude,
Longitude
Well Perforations
(feet below ground
surface)
Nearest Adjacent
Stream Well Category
Well A

38.23583,
-121.41869 14 – 31.5 Mokelumne River New ISW Well
Well B

38.245966,
-121.217862 25 – 35 Dry Creek New ISW Well
Well C

38.20457,
-121.09278 15 – 30 Mokelumne River New ISW Well
Well E

38.15838,
-121.14675 35 – 50 Mokelumne River New ISW Well
Well G

37.86248,
-120.77601 26 – 41 Little Johns Creek New ISW Well
Delta Well

38.1229,
-121.4932
125 – 150,
275 – 300 Mokelumne River New ISW Well
04N05E36H003

38.1559,
-121.3727 50 – 112 Mokelumne River GWL RMN
Swenson-3

38.0067,
-121.3458 194 – 204 San Joaquin River GWL RMN
Frankenheimer
(01S10E26J001M)

37.8163,
-120.8321 323 – 599 Stanislaus River GWL RMN
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Well ID Latitude,
Longitude
Well Perforations
(feet below ground
surface)
Nearest Adjacent
Stream Well Category
Burnett (OID-4)

37.7909,
-120.86752 168 – 249 Stanislaus River GWL RMN
02S07E31N001

37.7136,
-121.2508 130 – 226 San Joaquin River GWL RMN
02S08E08A001

37.781,
-121.1142 50 – 180 Stanislaus River GWL RMN
Representative groundwater level monitoring sites were selected from the GWL RMN for their proximity to identified interconnected surface water reaches, thorough and recent groundwater level observations, and known perforations.

The six new monitoring wells recently constructed, Well A, Well B, Well C, Well E, Well G and the Delta Well, were sited based on interconnected surface water data gaps described in the 2020 GSP and 2022 Revised GSP identifying a need for additional information on interconnected surface water to inform the SMC and to benefit future model calibration efforts. The specific well locations were further refined based on the additional criteria, including:
• The location of existing monitoring sites, including CASGEM Wells, SJC wells, USGS multi-completion wells, and other multi-completion wells.
• Areas with recharge and service water interaction
• Areas of critical overdraft
• Areas of water quality concern
• Areas in close proximity to subbasin boundaries
• Areas proximate to identified GDEs and interconnected surface water reaches • Areas to support future model refinement
• Property owned by one of the Subbasin GSAs.

The ISW RMN wells were selected to reflect both shallow, dynamic interactions between streams and the aquifer, as well as deeper regional pumping trends. Figure 4-4 shows the revised representative monitoring network for interconnected surface water.

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Figure 4-4: Representative Monitoring Network for Interconnected Surface Water EXHIBIT 1
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4.6.2 Monitoring Protocols for Interconnected Surface Water Data Collection and Monitoring Monitoring protocols for interconnected surface water representative monitoring wells are the same as those used for data collection from groundwater level representative monitoring wells. See Section 4.1.2 for the applicable protocols.

4.6.3 Frequency and Timing of Interconnected Surface Water Monitoring The frequency and timing of the collection of monitoring data from interconnected surface water representative monitoring wells are the same as those used for the monitoring of groundwater level representative monitoring wells.

See Section 4.1.3 for more detail on the frequency and timing of monitoring for the groundwater level RMN. Some wells will have transducers installed using American Rescue Plan Act (ARPA) funding allowing for more frequent groundwater level observation collection.

4.6.4 Spatial Density of Interconnected Surface Water Monitoring Network As with the representative monitoring network for groundwater level monitoring, the goal of the interconnected surface water monitoring network is to provide adequate spatial coverage within the Subbasin. This includes the ability to monitor and identify changes across the Subbasin boundaries (most of which are comprised of rivers), as well as along interconnected reaches within the Subbasin. The spatial location of monitoring wells in the network was based predominantly on proximity to interconnected reaches of the rivers and streams in the Subbasin.

4.7 DATA GAPS

4.7.1 Groundwater Level Data Gaps
Groundwater level monitoring data gaps exist in areas where data are limited. Specifically, areas of high data needs include monitoring near streams, Subbasin boundaries, and the groundwater depression in the central part of the Subbasin. Additionally, areas without multiple-completion wells present a limitation for depth-specific information collection. Additional sampling taken within these identified areas will provide more information about groundwater levels and trends in the indicated locations.

4.7.2 Groundwater Quality Data Gaps
Groundwater quality monitoring data gaps have four components:

1. Spatial distribution: Monitoring wells are mainly focused in the western portion of the Subbasin, as this area has historically had the highest concentrations of TDS. Additional sampling will provide more information about salinity both to provide more detailed understanding within areas with current monitoring coverage and to expand monitoring to areas without current salinity issues.

2. Well construction data: As described in Section 2.2.4, many wells with salinity measurements lack well depth and construction information. Both deeper and shallower groundwater quality monitoring wells are needed to better understand the spatial and depth distribution of salinity concentrations in the Subbasin.

3. Monitoring frequency: Temporally, groundwater quality monitoring occurs at different frequencies across the Subbasin, dependent on the monitoring agency responsible (summarized in Table 4-4). The groundwater quality monitoring network under the GSP will utilize a standardized, semi-annual monitoring schedule to facilitate the regular sampling of wells.

4. Monitoring for additional constituents: Groundwater quality concerns in the Subbasin are currently focused on salinity, represented by TDS and chloride as constituents of concern. Additional groundwater quality components such as arsenic and cations and anions, including nitrate, are monitored under existing water resources monitoring and management programs. Informational monitoring of these constituents may preempt future groundwater quality issues in the Subbasin.

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4.7.3 Interconnected Surface Water System Data Gaps
The ESJGWA recognizes the depletions of interconnected surface water as a data gap area. The ESJGWA has completed some refinements to the representative monitoring network, but a future study and additional refinement of interconnected surface water representative monitoring network will be needed, along with continued coordination efforts with neighboring subbasins to better inform Subbasin conditions and interconnected rivers that serve as boundaries for the Subbasin. As discussed in Section 7.4.1, future model calibration will be improved by more information on interconnected surface water, including the incorporation of additional shallow groundwater levels near interconnected stream reaches.

4.7.4 Groundwater-Dependent Ecosystem Data Gaps
The Natural Communities Commonly Associated with Groundwater (NCCAG) areas not identified as GroundwaterDependent Ecosystems (GDEs) through the GDE analysis are data gap areas requiring further evaluation and refinement to determine whether they require classification as a GDE. These areas include NCCAGs that either access co-occurring surface water, were identified as located in an area with groundwater levels deeper than 30 feet below the ground surface, or were located adjacent to irrigated agriculture. The purpose of this data gap is to identify potential existing GDEs that may have been incorrectly identified or not identified as GDEs through the GDE screening process discussed in Section 2.2.7 and Section 2.3.7. Potential impacts to fish and wildlife species associated with GDEs that occur as a result of groundwater pumping under and are not captured under the depletions of interconnected surface water sustainability indicator is also considered a data gap area. Additional detail on this data gap is discussed in Appendix 3-C.

4.7.5 Plan to Fill Data Gaps
Data gaps will be largely filled by leveraging existing wells, constructing new wells, additional water quality monitoring, modeling, and studies of interconnected surface water and GDEs, which are discussed in Chapter 7: Plan Implementation. These efforts will be supported through a combination of funding and financing sources, including through DWR Technical Support Services (TSS) funding, future grant funding, and GSA funding. A description of data collection and analysis efforts to fill data gaps, and information on how these efforts will be funded, is provided in Chapter 7: Plan Implementation.

There are up to 12 proposed new monitoring well sites (shown in Figure 4-5 as orange diamonds). Progress has been made toward drilling new wells at 6 sites since the 2020 GSP (shown as circles with orange outlines). New wells will be measured for groundwater levels and/or groundwater quality, depending on the data gap for which the well is intended to fill. The locations of the proposed monitoring wells are subject to change based on the needs of the Subbasin and well siting feasibility. Additional multi-completion groundwater level information will assist with better understanding of groundwater-surface water interaction and GDEs. Future multi-completion wells and/or well pairs may be constructed to support the efforts to understand groundwater levels and quality at varying depths in the Subbasin.

Additional new shallow groundwater level and quality monitoring wells located near streams, Subbasin boundaries, and the groundwater depression area in the center of the Subbasin will also improve the understanding of aquiferstream dynamics. The proposed locations of these wells will be selected to be co-located with identified and potential GDE areas and near streams to further understanding of groundwater-surface water connectivity and to refine GDE data gaps. Additionally, groundwater level data collected from these wells will improve the understanding of groundwater flows between subbasins and groundwater quality data will assist in tracking quality in different areas of the Subbasin. Relevant data from these and other wells will be shared with GSAs in neighboring subbasins, and parallel efforts will be coordinated.

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The USGS National Field Manual for the Collection of Water Quality Data (USGS, var.) will be used as a guide for selection of wells, well locations, and collection of reliable data, as recommended by DWR’s Monitoring Protocols, Standards, and Sites BMP (CA DWR, 2016a). Requirements are summarized in Table 4-9. The DWR’s California Well Standards, Bulletin 74-81 and 74-90 will be used as references for guidance for construction of new monitoring well installation, per DWR’s Best Management Practices for the Sustainable Management of Groundwater Monitoring Protocols, Standards, and Sites (CA DWR, 2016a). Additionally, procedures will follow applicable San Joaquin County, Calaveras County, or Stanislaus County well standards, including proper permitting and inspection from the applicable county for each well.

Aside from new groundwater monitoring wells, data gaps will also be addressed through additional analyses of interconnected surface water, including additional refinement of GDEs, and through the use of publicly available data collected by others in the Subbasin. The ESJGWA plans to conduct field verification of the potential GDE sites identified in Appendix 3-C. This field exercise will assess both species presence and source of water for each ecosystem. The results of this study, combined with additional shallow groundwater level data collected at new wells, will determine what additional regional or site-specific biological analyses may be needed to effectively assess locations of GDEs and appropriately manage impacts to them. Future projects and management actions may be developed to address these needs once there is sufficient data to evaluate GDEs effectively.

Additional activities related to filling data gaps are discussed in Chapter 6: Projects and Management Actions and Chapter 7: Plan Implementation.

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Figure 4-5: Proposed New Monitoring Well Locations (Shown as Orange Diamonds) EXHIBIT 1
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Table 4-9: Considerations for Well Selection and Well Installation Well Location
• Location conforms to the study’s network design for areal and depth distribution. • Land-use/land-cover characteristics, if relevant, are consistent with study objectives. • Site is accessible for equipment needed for well installation and sample collection.

Hydrogeologic Unit(s)
• Hydrogeologic unit(s) that contribute water to the well can be identified. • Depth and thickness of targeted hydrogeologic unit(s) are known or can be determined. • Yield of water is adequate for sampling (typically, a minimum of 1 gallon (3.785 liters) per minute).

Well Records, Description, Design, Materials, and Structure • Available records (for example, logs of well drilling, completion, and development) have sufficient information to meet the criteria established by the study.
• Borehole or casing/screen diameter is adequate for equipment. • Depth to top and bottom of sample-collection (open or screened) interval is known (to determine area contributing water to well).
• Length of well screen is proportional to the vertical and areal scale of investigation. • Well has only one screened or open interval in one aquifer, if possible. (Packers can be used to isolate the interval of interest, but packers might not completely isolate zones in unconsolidated or highly fractured aquifers.

If packers are used, materials of construction must be compatible with analytes to be studied.) • Top of well screen is several feet below mean annual low-water table to reduce chances of well going dry and to avoid sampling from unsaturated intervals.
• Filter pack is of a reasonable length (a long interval compared with length of screened or open interval usually results in uncertainty as to location of the source of water to well). • Well-construction materials do not leach or sorb substances that could alter ambient target-analyte concentrations.
• Well-structure integrity and communication with the aquifer are sound. (Checks include annual depth-to-bottom measurements, borehole caliper and downhole-camera video logs, and aquifer tests.) Pump Type, Materials, Performance, and Location of Sampler Intake • Supply wells have water-lubricated turbine pumps rather than oil-lubricated turbine pumps. (Avoid suction-lift, jet, or gas-contact pumps, especially for analytes affected by pressure changes, exposure to oxygen, or that partition to a gas phase.)
• Pump and riser-pipe materials do not affect target-analyte concentrations. • Effects of pumping rate on measurements and analyses have been or will be evaluated. • Samples intake is ahead of where water enters treatment systems, pressure tanks, or holding tanks.

Source: National Field Manual for the Collection of Water-Quality Data (USGS, var.) EXHIBIT 1
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5. DATA MANAGEMENT SYSTEM
This chapter includes the Data Management System Section that satisfies §352.6 of the Sustainable Groundwater Management Act Regulations. This section contains three main subsections:
• Overview of the Eastern San Joaquin Subbasin Data Management System • Functionality of the Data Management System
• Data Included in the Data Management System

5.1 OVERVIEW OF THE EASTERN SAN JOAQUIN SUBBASIN DATA MANAGEMENT SYSTEM
The Eastern San Joaquin Subbasin Data
Management System (DMS) is implemented using
the Opti platform. The DMS serves as a data
sharing portal to enable utilization of the same data
and tools for visualization and analysis to support
sustainable groundwater management and
transparent reporting of data and results.

The DMS is web-based and publicly accessible
using common web browsers including Google
Chrome, Firefox, and Microsoft Edge. It is a
flexible and open software platform that utilizes
familiar Google maps and charting tools for
analysis and visualization. The site may be
accessed here: https://opti.woodardcurran.com/esj

5.2 FUNCTIONALITY OF THE DATA MANAGEMENT SYSTEM
The DMS is a modular system that includes numerous tools to support Groundwater Sustainability Plan (GSP) development and ongoing implementation, including:
• User and Data Access Permissions
• Data Entry and Validation
• Visualization and Analysis
• Query and Reporting
The DMS can be configured for additional tools and functionality as the needs of the Eastern San Joaquin Groundwater Authority (ESJGWA) change over time. The following sections briefly describe the currently configured tools. For more detailed instructions on the usage of the DMS, please refer to the Opti Public User Guide (the Opti Public User Guide can be accessed online at https://opti.woodardcurran.com/esj/upload/OptiPublicDMS_Guide.pdf.

Figure 5-1: Opti DMS Screenshot
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5.2.1 User and Data Access Permissions
User access permissions are controlled through several user types that have different roles in the DMS as summarized in Table 5-1 below. These user types are broken into three high-level categories:
• System Administrator users manage information at a system-wide level, with access to all user accounts and entity information. System Administrators can set and modify user access permissions when an entity is unable to do so.
• Managing Entity (Administrator, Power User, User) users are responsible for managing their entity’s site/monitoring data and can independently control access to this data. Entity users can view and edit their entity’s data and view (not edit) shared or published data of other entities. An entity’s site information (wells, gages, etc.) and associated data may only be edited by Administrators and Power Users associated with the entity.
• Public users may view data that are published but may not edit any information. These users may access the DMS using the Guest Login feature on the login screen.

Monitoring sites and their associated datasets are added to the DMS by Managing Entity Administrators or Power Users. In addition to the user permissions, access to the monitoring datasets is controlled through three options:
• Private data are monitoring data that are only available for viewing, depending on user type, by the entity’s associated users in the DMS.
• Shared data are monitoring data that are available for viewing by all users in the DMS (excludes Public Users).
• Public data are monitoring data that are available publicly and can be viewed by all user types in the DMS and may be published to other sites or DMSs as needed.

The Managing Entity Administrators have the ability to set and maintain the data access options for each dataset associated with their entity.

Table 5-1: Data Management System User Types
Entity
Modules/Submodules System
Administrators
Admin Power User User Public
Data: Map ● ● ● ● ○
Data: List ● ● ● ● ○
Data: Add/Edit ● ● ●
Data: Import ● ● ●
Query ● ● ● ● ○
Admin ●
Profile ● ● ○ ○ ○
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● Indicates access to all functionality, ○ Indicates access to partial functionality (see explanations in following sections)

5.2.2 Data Entry and Validation
To encourage agency and user participation in the DMS, data entry and import tools are easy to use, accessible over the web, and help maintain data consistency and standardization. The DMS allows Entity Administrators and Power Users to enter data either manually via easy-to-use interfaces, or through an import tool utilizing Excel templates, ensuring data may be entered into the DMS as soon as possible after collection. The data are validated by Managing Entity’s Administrators or Power Users using a number of quality control checks prior to inclusion in the DMS.

As part of the 2020 GSP and 2022 Revised GSP implementation, a mobile and tablet interface was developed for the DMS to facilitate the real-time upload of data collected in the field. The Eastern San Joaquin (ESJ) Data Management System (DMS) mobile interface is implemented using the Esri ArcGIS Field Maps mobile app (or the Collector app if already installed) and is integrated with the DMS via web services to ArcGIS Online.* The mobile interface is intended to provide all ESJ staff and their consultants with easy-to-use interfaces to collect well and groundwater related data in the field. Data collected using the mobile interfaces are pulled into the DMS on a nightly basis where it is quality controlled prior to insertion into the database.

5.2.2.1 Data Collection Sites
Site information is input for groundwater wells, stream gages, and precipitation meters manually either through the Data Entry tool or when prompted in the Import tool. In the Data Entry tool, new sites may be added by clicking on New Site. Existing sites may be updated using the Edit Site tool. During data import, the sites associated with imported data are checked by the system against the existing site list in the DMS. If the site is not in the existing site list, the user is prompted to enter the information via the New Site tool before the data import can proceed.

The information that is collected for sites is shown in Table 5-2. Required fields are indicated with an asterisk.

Table 5-2: Data Collection Site Information
Basic Info Well Info Construction Info
Site Type*
Local Site Name*
Local Site ID
Latitude/Longitude*
Description
County
Managing Entity*
Monitoring Entity*
Type of Monitoring
Type of Measurement
Monitoring Frequency
State Well ID

CASGEM ID
Ground Surface Elevation
Reference Point
Reference Point Elevation
Reference Point Location
Reference Point Description
Well Use
Well Status
Well Type
Aquifers Monitored
Groundwater Subbasin Name/Code
Comments
Upload File
Total Well Depth
Borehole Depth
Casing Perforations
Casing Diameter
Casing Modifications
Well Capacity
Well Completion Report Number
Comments
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* Required fields; all other fields are optional

5.2.2.2 Monitoring Data Entry
Monitoring data, including but not limited to
groundwater elevation, groundwater quality,
streamflow, and precipitation, may be input
either manually through the Data Entry tool or
using templates in the Import tool. The Data
Entry tool allows users to select a site and add
data for the site using a web-based tool (see
Figure 5-2). The following information is
collected:
• Data Type (e.g., groundwater
elevation, groundwater quality,
streamflow, or precipitation)
• Parameter for selected Data Type, units populate based on selection • Date of Measurement
• Measurement Value
• Quality Flag (e.g., quality assurance description for the measurement such as “Pumping”, “Can’t get tape in casing”, etc., as documented by the Data Collector)
• Data Collector
• Supplemental Information based on Data Type (e.g., Reference Point Elevation, Ground Surface Elevation, etc.)
Data import templates include the same data entry fields and are available for download from the DMS. The Excelbased templates contain drop-down options and field validation similar to the data entry interface.

5.2.2.3 Data Validation
Quality control helps ensure the integrity of the data added to the DMS. The entities that maintain the monitoring data that were loaded into the DMS may have performed previous validation of that data; no effort was made to check or correct that previous validation and it was assumed that all data provided was valid. While it is nearly impossible to determine complete accuracy of the data added to the DMS since the DMS cannot detect incorrect measurements due to human error or mechanical failure, it is possible to verify that the data input into the DMS meets some data quality standards. This helps promote user confidence in the data stored and published for visualization and analysis.

Upon saving the data in the data entry interface or importing the data using the Excel templates, the following data validation checks are performed by the DMS:
• Duplicate measurements: The database checks for duplicate entries based on the unique combination of site, data type, date, and measurement value.
• Inaccurate measurements: The database compares data measurements against historical data for the site and flags entries that are outside the historical minimum and maximum values.

Figure 5-2: DMS Data Entry Tool
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• Incorrect data entry: Data field entries are checked for correct data type (e.g., number fields do not include text, date fields contain dates, etc.)
Users are alerted to any validation issues and may either update the data entries or accept the values and continue with the entry/import. Users may access partially completed import validation through the import logs that are saved for each data import. The partially imported data are identified in the Import Log with an incomplete icon under the Status field. This allows a second person to access the imported data and review prior to inclusion in the DMS.

5.2.3 Visualization and Analysis
Transparent visualization and analysis tools enable utilization of the same data and methodologies, allowing stakeholders and neighboring Groundwater Sustainability Agencies (GSAs) to use the same data and methods for tracking and analysis. In the Eastern San Joaquin Subbasin DMS, data visualization and analysis are performed in both Map and List views.

The Eastern San Joaquin Subbasin DMS underwent refinement in 2023 to improve streamlining of communication of subbasin status to the public and improved access to SGMA-related data. The refined DMS portal is conceived as a simple-to-use public portal that pulls data directly from the ESJ SGMA DMS into an easy-to-understand and interactive website. The new Groundwater Portal also provides access to other subbasin information and websites. Upon entering the Groundwater Portal of the DMS (Figure 5-3), users who wish to login may click on the “Member Login” button to access the existing DMS for data updates, analysis, and reporting. Public users may access the GSP, view a list of member GSAs, read the latest annual report, and visit the ESJ Groundwater Authority webpage.

Figure 5-3: Landing Page of Groundwater Portal
The updated portal also includes a “Progress-At-A-Glance” link or scrolling down displays the ESJ Subbasin dashboard, as shown in Figure 5-4. The dashboard is intended to give a quick and easy-to-understand snapshot of the subbasin conditions. The dashboard framework is ready to be populated when and if the ESJ Groundwater Authority determines what information should be made available to the public.

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Figure 5-4: Progress-At-A-Glance Dashboard

5.2.3.1 Map View
The Map view displays all sites
(groundwater wells, stream gages,
precipitation meters, etc.) in a
map-based interface (see Figure
5-5). The sites are color coded
based on associated data type
and may be filtered by different
criteria such as number of records
or monitoring entity. The ESJ Plan
Data map is an interactive map
interface built utilizing the ArcGIS
JavaScript API, ArcGIS Online,
and a live link to the ESJ SGMA
DMS data. The map interface includes geospatial information, search functions based on address or place, map filters, and data view and download functions. Users may click on a site to view the site detail information and associated data. The monitoring data are displayed in both chart and table formats. In these views, the user may select to view different parameters for the data type. The chart and table may be updated to display selected date ranges, and the data may be exported to Excel.

5.2.3.2 List View
The List view displays all sites (groundwater wells, stream gages, precipitation meters, etc.) in a tabular interface. The sites are listed according to site names and associated entities. The list can be sorted and filtered by different criteria such as number of records or monitoring entity. Similar to the Map view, users may click on a site to view the site detail information and associated data. The monitoring data are displayed in both chart and table formats. In these views, the user may select to view different parameters for the data type. The chart and table may be updated to display selected date ranges, and the data may be exported to Excel.

Figure 5-5: Typical DMS Data Display
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5.2.3.3 Analysis Tools
The Toolbox is available in the Map view and offers Administrative and Entity users access to the Well Tiering tool to support monitoring plan development. The flexibility of the DMS platform allows for future analysis tools, including contouring, total water budget visualization, and management area tracking.

5.2.4 Query and Reporting
The DMS has the ability to format and export data and analysis at different levels of aggregation, and in different formats, to support local decision making and for submission to various statewide and local programs (i.e., the Sustainable Groundwater Management Act [SGMA], California Statewide Groundwater Elevation Monitoring [CASGEM], groundwater ambient monitoring and assessment [GAMA], etc.). Additionally, data contained in the DMS may be viewed and downloaded. Clicking on the representative monitoring well in the map view will open a modal (pop-out window) to view and download data. The modal displays a hydrograph along with the Measurable Objective and Minimum Threshold for the well. A tabular view of the data is also available. All data can be printed or downloaded to the user’s selected location in Excel format.

5.2.4.1 Ad-hoc Query
The data in the DMS can be queried and reported using the Query Tool. The Query Tool includes the ability to build ad-hoc queries using simple options. The data can be queried by:
• Monitoring or Managing Entity
• Site Name
• Data Type
Once the type of option is selected, the specific criteria may be selected (e.g., groundwater elevation greater than 100 ft.). Users may also include time periods as part of the query. The query options can build upon each other to create reports that meet specific needs. Queries may be saved and will display in the saved query drop-down menu of the user who created the query for future use.

The query results are displayed in a map format and a list format. In both the Map and List views, the user may click on a well to view the associated data. The resulting data of the query may be exported to Excel.

5.2.4.2 Standard Reports
The DMS can be configured to support wide-ranging reporting needs through the Reports tool. Standard report formats may be generated based on a predetermined format and may be created at the click of a button. These report formats may be configured to match state agency requirements for submittals, including annual reporting of monitoring data that must be submitted electronically on forms provided by the Department of Water Resources (DWR).

5.3 DATA INCLUDED IN THE DATA MANAGEMENT SYSTEM
Many monitoring programs exist at both the local and state/federal levels. A cross-sectional analysis was conducted within the Subbasin to document and assess the availability of data within the Subbasin, as well as statewide or federal databases that provide data relevant to the Subbasin.

The DMS is configured to include a wide variety of monitoring data types and associated parameters. Based on the analysis of existing datasets within the Subbasin and the GSP needs, the data types shown in Table 5-3 below were identified and are currently used in the DMS.

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Table 5-3: Data Types and Their Associated Parameters Configured in the DMS Data Type Parameter Units
Currently
Has Data in
DMS
Groundwater Level Depth to Groundwater feet Yes
Groundwater Elevation feet Yes
Groundwater Quality Chloride milligrams per liter Yes
Electrical Conductivity umhos/cm Yes
Total Dissolved Solids milligrams per liter Yes
Various Parameters (See Appendix 5-A) various
Surface Water Quality Various Parameters (See Appendix 5-A) various Streamflow Streamflow cubic feet per
second
Precipitation Precipitation inches
Reference Evapotranspiration (ETo) inches per month
Average Air Temperature ºF
Additional data types and parameters can be added and modified as the DMS grows over time. The data were collected from a variety of sources, as shown in Table 5-4 below. Each dataset was reviewed for overall quality and consistency prior to consolidation and inclusion in the database.

The groundwater wells shown in the DMS are those that are included datasets provided by the monitoring data sources shown below for groundwater elevation and quality. These do not include all wells currently used for production and may include wells historically used for monitoring that do not currently exist. Care was taken to minimize duplicative wells in the DMS. As datasets were consolidated, sites were evaluated based on different criteria (e.g., naming conventions, location, etc.) to determine if the well was included in a different dataset. Datasets for the wells were then associated with the same well, where necessary.

After the data were consolidated and reviewed for consistency, it was loaded into the DMS. Using the DMS data viewing capabilities, the data were reviewed for completeness and consistency to ensure the imports were successful.

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Table 5-4: Sources of Data Included in the Data Management System Data Source Datasets Collected Date
Collected Activities Performed
Central Valley Salinity
Alternatives for LongTerm Sustainability
(CVSALTS)
Well Location
Well Type (Limited)
Well Depth (Limited)
Groundwater Quality
8/13/2018 • Removed duplicate records
• Matched existing records with
other data sources (GAMA,
DWR)
DWR CASGEM Groundwater Elevation
Well Type (Limited)
Well Depth (Limited)
Well Location
4/18/2018 • Removed duplicate records
EnviroStor Groundwater Quality 7/23/2018 • Removed duplicate records GeoTracker Groundwater Quality 7/23/2018 • Removed duplicate records GAMA Well Type
Well Depth (Limited)
Well Location
Groundwater Quality
8/2/2018 • Removed duplicate records
Local Data Groundwater Elevation (Limited)
Well Type (Limited)
Well Depth
Well Location
Groundwater Quality
2/2017-
10/2018
• Removed duplicate records
San Joaquin County
Flood Control and
Water Conservation
District
Groundwater Elevation
Well Type (Limited)
Well Depth (Limited)
Well Location
9/19/2017 • Removed duplicate records
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-1
Projects and Management Actions November 2024

6. PROJECTS AND MANAGEMENT ACTIONS
This chapter includes relevant projects and management actions information to satisfy California Code of Regulations (CCR) Title 23 §354.42 and 354.44. The projects and management actions described in this chapter will help achieve the Eastern San Joaquin Subbasin’s sustainability goal.

6.1 PROJECTS, MANAGEMENT ACTIONS, AND ADAPTIVE MANAGEMENT STRATEGIES Achieving sustainability in the Eastern San Joaquin Subbasin (Subbasin) requires implementation of projects and management actions. The Eastern San Joaquin Subbasin will achieve sustainability by implementing water supply projects that either replace (offset) or supplement (recharge) groundwater to achieve the estimated pumping offset and/or recharge need of 95,000 acre-feet per year (AF/year), identified as part of the sustainable yield estimate presented in Section 2.4.6. In addition, three projects have been identified that support demand conservation activities, including water use efficiency upgrades. Currently, no pumping restrictions have been proposed for the Subbasin; however, Groundwater Sustainability Agencies (GSAs) are currently working on developing a demand reduction program and maintain the flexibility to implement such demand-side management actions in the future if need is determined.

6.2 PROJECTS

6.2.1 Project Identification
Projects were identified by the Eastern San Joaquin GSAs through a several-month process involving the Eastern San Joaquin Groundwater Authority Board of Directors (ESJGWA Board), Advisory Committee, Workgroup, and the general public. This process included a public polling and feedback solicitation process at the Projects and Management Actions Workshop, held at the October 2018 ESJGWA Board meeting. This activity allowed ESJGWA Board members, GSA staff, and members of the public to participate in a real-time online polling activity through their smart-phone devices. Hard-copy paper surveys were provided for those without online access. Additionally, a template for project feedback and suggestion was created, posted online for the public, and hard copies distributed at Informational Open House events.

Project information was provided by GSAs and compiled into a draft list. This list was discussed and presented during the October and November 2018 ESJGWA Board meetings, the October and November 2018 and January 2019 Advisory Committee meetings, and the November 2018 and January 2019 Workgroup meetings. Priorities identified included:
• Project is implementable with respect to technical complexity, regulatory complexity, institutional consideration, and public acceptance
• Project benefit is located in area of greatest overdraft • Project is affordable and cost-effective (lowest unit cost per volume water savings) • Project provides an environmental benefit (or reduces environmental impact) • Project addresses Disadvantaged Communities (DACs) and/or Severely Disadvantaged Communities (SDACs)
• Project is located in an area where water quality is suitable for use Projects with the potential to contribute to the migration of a potential contaminant plume were eliminated from consideration and removed from the GSP list of projects.

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2024 Groundwater Sustainability Plan Amendment 6-2
Projects and Management Actions November 2024
The resultant list of projects and management actions was then updated in coordination with the 5-year Periodic Evaluation and this GSP amendment. Updated project information was solicited from the GSAs, and the list of projects and management actions revised to reflect plans as of 2024.

6.2.2 Project Implementation
Projects will be administered by the GSA project proponents. GSAs may elect to implement projects individually or jointly with one or more GSAs or with the ESJGWA. As the ESJGWA develops GSA-level water budgets, the GSAs will have a better understanding of how projects will be implemented at the GSA-level and can better evaluate progress toward completion.

6.2.3 List of Projects
Several projects to increase water supply availability in the Subbasin were identified. The initial set of projects was reviewed with the ESJGWA Board, Advisory Committee, and Workgroup. A final list of 45 possible projects is included in the GSP, representing a variety of project types including direct and in-lieu recharge, intra-basin water transfers, demand conservation, water recycling, and stormwater reuse. Projects are classified into two categories based on project status as defined below.
• Category A projects - projects that were completed or are anticipated to advance in the next five years and have existing water rights or agreements.
• Category B projects - projects that are not anticipated to advance in the next five years, but may be implemented in the future, particularly if Category A projects do not fully achieve stated recharge and/or offset targets or do not produce a response as simulated in the model.

This subsection of the GSP satisfies the requirements of CCR Title 23 §354.44. Consistent with SGMA requirements, the project descriptions for projects contain information regarding:
• The benefitted measurable objective
• Permitting and regulatory processes
• Time-table for initiation and completion
• Expected benefits
• How the project will be accomplished
• Legal authority
• Estimated costs and plans to meet costs
• Implementation circumstances
• Public noticing
Table 6-1 provides a summary of 41 of the 45 projects; full descriptions are included below. Figure 6-1 and Figure 6-2 shows the locations of these projects.

During the September 11, 2024 ESJGWA Board Meeting, the Board approved by resolution the addition of 5 projects to the GSP. These projects include:
• Mariposa Drain Water Delivery Improvement Project – Central San Joaquin Water Conservation District GSA
• South System Pipeline Phase 4 Improvement Project – North San Joaquin Water Conservation District GSA
• Q/Qc Conjunctive Use Project – South San Joaquin GSA
• SSJID Advanced Metering Infrastructure Project – South San Joaquin GSA • Clements Road Pipeline Project – Stockton East Water District EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-3
Projects and Management Actions November 2024
The South System Pipeline Phase 4 Improvement Project is already included in the 41 projects listed in Table 6-1 and is discussed in Section 6.2.4.5. The other four are new additions that are not included in Table 6-1, nor in the write-ups included in this chapter. More information on these projects is included in Appendix 6-A. With the addition of these four projects, the GSP now includes 45 total projects.

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2024 Groundwater Sustainability Plan Amendment 6-4
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Table 6-1: List of SGMA Projects
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Cost
Estimated
Annual O&M
Cost
Required
Permitting and
Regulatory
Process1
Maximum
Recharge
Benefit
(AF/year)
Category A Projects - projects that were completed or are anticipated to advance in the next five years and have existing water rights or agreements Lake Grupe Inlieu RechargeIn-lieu Recharge SEWD Groundwater levels
Completed 2020-2023 $2.3 M $330,000 Installation for
new intake and
pipeline requires
permits from

DFW, CVFPB,
RWQCB, and
USACE
4,900
SEWD Surface
Water
Implementation
Expansion
In-lieu Recharge SEWD Groundwater
levels
Implementation 2019-2029 $750,000 $100,000 Permit approvals from DFW,
RWQCB,
CVFPB, and
USACE by
private
landowners
19,000
White Slough
Water Pollution
Control Facility
Expansion
Recycling/
In-lieu
Recharge/Direct
Recharge
City of Lodi Groundwater
levels
Construction
complete
2019-2020 $6 M $4,664 None (permitting
complete)
1,000
CSJWCD Capital
Improvement
Program
In-lieu Recharge CSJWCD Groundwater
levels
Can be implemented
immediately
2020-2027, ongoing with 7-
year completion
cycles
N/A $50,000 Individual
applications
need CSJWCD
Board approval
and possible
streambed
alteration
permits
24,000
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-5
Projects and Management Actions November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Cost
Estimated
Annual O&M
Cost
Required
Permitting and
Regulatory
Process1
Maximum
Recharge
Benefit
(AF/year)
NSJWCD South
System
Modernization
In-lieu Recharge NSJWCD Groundwater
levels
Environmental review
complete, funding
secured for Phases 1,
2 and 3. Landowner
improvement district
formed. Phases 1-2
complete.
2018-2025 for
Phases 1, 2, 3;
2025-2028 for
Phase 4; 2028-
2035 for future
phases
Phase 1&2:
$7 M
Phase 3:
$4 M
Phase 4:
$8 M
Future
Phases:
$10-20 M
Phase 1&2:
$200,000
Phase 3:
$200,000
Phase 4:
$200,000
Future Phases:
$200,000
Permits for
pump station
work have been
completed;
minor grading
and road
encroachment
permits may be
needed
10,000
Long-term Water
Transfer to
SEWD and
CSJWCD
Transfers SSJ GSA Groundwater
levels
Infrastructure is in
place. CEQA
completed and
agreements in place
2019-2021 N/A $9 M Project must
comply with
CEQA
20,000
South System
Groundwater
Banking with
East Bay
Municipal Utilities
District (EBMUD)
In-lieu Recharge NSJWCD Groundwater
levels
Pilot Dream Project
will be completed in
April 2024. Working
on expanded banking
project
2020-2024 $5 M $400,000
SWCRB change
petition for
Permit 10478
and San Joaquin
County
groundwater
export permit,
and regulatory
permits as
needed
4,000
NSJWCD North
System
Modernization/
Lakso Recharge
In-Lieu Recharge NSJWCD Groundwater
levels
Constructed Phase
1A, in progress on
Phase 1B. Planning
Phase 2
2021-2026 $7 M $150,000
Regulatory
permits as
needed
4,000
Tecklenburg
Recharge Project Direct Recharge NSJWCD Groundwater levels Substantially
complete 2022-2024 $1 M $400,000
CEQA review
and possible
grading permit
2,000
City of Stockton
Phase 1:

Groundwater
Recharge Project
Direct Recharge City of
Stockton
Groundwater
levels
Basin design in
progress.

Construction to begin
spring 2025.
2022-2026 $11.5 M To be
Determined
Project must
comply with
CEQA
20,000
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-6
Projects and Management Actions November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Cost
Estimated
Annual O&M
Cost
Required
Permitting and
Regulatory
Process1
Maximum
Recharge
Benefit
(AF/year)
West
Groundwater
Recharge Basin
Direct Recharge SEWD Groundwater
levels
Ongoing 2032 To be
Determined
To be
Determined
To be
Determined
16,000
NSJWCD Private
Pump
Partnerships
In-Lieu
Recharge/Direct
Recharge
NSJWCD Groundwater
levels Ongoing 2024 To be Determined
To be
Determined
To be
Determined 3,000
Oakdale
Irrigation District
In-lieu and Direct
Recharge Project
Direct Recharge/InLieu Recharge OID Groundwater
levels Ongoing 2023-2032 To be Determined
To be
Determined
To be
Determined 25,000
City of Stockton
Advanced
Metering
Infrastructure
Conservation City of
Stockton
Groundwater
levels
In progress. Contract
awarded in March
2024.
2023-2028 $17 M To be
determined
Not determined 2,000
Total Category A 154,900
Category B Projects - projects that are not anticipated to advance in the next five years, but may be implemented in the future, particularly if Category A projects do not fully achieve stated recharge and/or offset targets or do not produce a response as simulated in the model City of
Manteca
Advanced
Metering
Infrastructure
Conservation City of
Manteca
Groundwater
levels
Experiencing Delays Not determined $650,000 $300,000 None 272 City of Lodi
Surface Water
Facility
Expansion &
Delivery
Pipeline
In-lieu Recharge City of
Lodi
Groundwater
levels
Planning phase 2030-2033 $4 M $2,340,000 SWRCB
permitting and
CEQA required
4,750
EXHIBIT 1
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Projects and Management Actions November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Cost
Estimated
Annual O&M
Cost
Required
Permitting and
Regulatory
Process1
Maximum
Recharge
Benefit
(AF/year)
BNSF Railway
Company
Intermodal
Facility
Recharge
Pond
Direct Recharge CSJWCD Groundwater
levels
Planning phase 2020-2025 N/A $50,000 Streambed
alteration permit
1,000
Manaserro
Recharge
Project
Direct Recharge NSJWCD Groundwater
levels
Planning phase 2023-2025 $500,000 $50,000 CEQA review,
possible grading
permit, possible
water right
change petition
8,000
City of Escalon
Wastewater
Reuse
Recycling/
In-lieu Recharge/
Transfers
SSJ GSA Groundwater
levels
Planning phase 2020-2028 To be
determined
To be
determined
CEQA review,
RWQCB
permits, and
road
encroachment
permits
672
City of Ripon
Surface Water
Supply
In-lieu Recharge SSJ GSA Groundwater
levels
Design complete;
environmental
permitting underway;
negotiations for the
right to connect are
underway.
2028-2030 To be
determined
To be
determined
NEPA
Categorical
Exclusion,
CEQA Mitigated
Negative
Declaration, and
road
encroachment
permits
6,000
City of Escalon
Connection to
Nick DeGroot
Water
Treatment
Plant
In-lieu Recharge SSJ GSA Groundwater
levels
Conceptual design;
environmental review
complete; Council
approval are pending
further design work
and rate study
2028-2030 To be
determined
To be
determined
Road
encroachment
permits
2,015
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-8
Projects and Management Actions November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Cost
Estimated
Annual O&M
Cost
Required
Permitting and
Regulatory
Process1
Maximum
Recharge
Benefit
(AF/year)
Farmington
Dam
Repurpose
Project
Direct Recharge SEWD Groundwater
levels
Planning/Initial Study 2030-2050 To be
determined
To be
determined
Permits and
approvals form

SWRCB, USBR,

DFW, RWQCB,
CVFPB, and
USACE
60,000
Mobilizing
Recharge
Opportunities
Direct Recharge San
Joaquin
County
Groundwater
levels
Project Development 2024-2040 Not
determined
Not determined Not determined 158,000
NSJWCD
Winery
Recycled
Water
Recycling/
In-Lieu Recharge/
Direct Recharge
NSJWCD Groundwater
levels
Conceptual planning
and discussion
2025-2027 To be
determined
To be
determined
WDR permitting
through the
RWCQB and
minor permits for
pipeline
construction
750
SSJID Storm
Water Reuse
Storm Water/
In-lieu Recharge/
Direct Recharge
SSJ GSA Groundwater
levels
Planning phase 2027-2030 To be
determined
To be
determined
CEQA review
and road
encroachment
permits
1,100
WallaceBurson
Conjunctive
Use Program
Conjunctive
Use/Direct Recharge
Eastside
GSA
Groundwater
levels
Conceptual planning
and discussion 2030-2040 To be determined
To be
determined Not determined 3,000
Calaveras
River
Wholesale
Water Service
Expansion
In-Lieu Recharge Eastside
GSA
Groundwater
levels Conceptual planning 2020-2040 To be determined
To be
determined Not determined 600
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-9
Projects and Management Actions November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Cost
Estimated
Annual O&M
Cost
Required
Permitting and
Regulatory
Process1
Maximum
Recharge
Benefit
(AF/year)
Recycled
Water to
Manteca Golf
Course
Recycling City of
Manteca
Groundwater
levels
12-in pipeline
installed. Waiting for
DWR to determine
grant recipients
To Be
Determined
To be
determined
To be
determined Not determined 406
Threfall Ranch
Reservoir, InLieu and Direct
Recharge
Project
In-Lieu
Recharge/Direct
Recharge
Eastside
GSA
Groundwater
levels Design 2025 To be determined
To be
determined Not determined 2,000
Perfecting
Mokelumne
River Water
Right
In-Lieu Recharge
San
Joaquin
County
Groundwater
levels Planning 2024-2025
$125,000
(spent to date)
Total TBD
To be
determined Not determined 158,000
North System
Groundwater
Recharge
Project - Phase
2 Direct Recharge NSJWCD Groundwater
levels
Design phase with
planned construction
in 2025-2026
2026-2029 $10 M $100,000 Not determined 3,000
Stormwater
Collection,
Treatment, and
Infiltration
Direct Recharge/
Stormwater
City of
Manteca
Groundwater
levels Planning/Initial Study To Be Determined
To be
determined
To be
determined Not determined To Be Determined
Off-Stream
Regulating
Reservoir
Direct Recharge SEWD Groundwater
levels Conceptual Phase 2026-2050 To be determined
To be
determined Not determined To Be Determined
On-Farm
Recharge
Project
Direct Recharge SEWD Groundwater
levels Planning/Initial Study 2024-2030 N/A $100,000 Not determined To Be Determined EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-10
Projects and Management Actions November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Cost
Estimated
Annual O&M
Cost
Required
Permitting and
Regulatory
Process1
Maximum
Recharge
Benefit
(AF/year)
Bellota Weir
Modifications
Project
Direct Recharge/
Stormwater SEWD Groundwater
levels
SRF Loan Application
Submitted. $12.3M
Grant awarded. Minor
construction started
2023-2030 $ 85 M $1.5M
USACE,

USFWS,CVFPB,

NEPA,CEQA,R
WQCB
5,200
Water Supply
Enhancement
Project -
Distribution
Pipelines
In-Lieu
Recharge/Direct
Recharge
SEWD Groundwater
levels Design 2024-2040 $7M To be determined

RWQCB,CEQA,

USACE,CVFPB,
CDFW
17,000
Water
Treatment
Plant Aquifer
Storage
Recovery Well
- 7401
Direct Recharge SEWD Groundwater
levels Implementation 2024-2026 $1.5 M To be determined

RWQCB,CEQA,
NEPA 2,420
Beckman Well Direct Recharge SEWD Groundwater
levels Refurbish 2024-2028 $200,000 N/A RWQCB,CEQA 800
West Linden
Project
In-Lieu
Recharge/Direct
Recharge
SEWD Groundwater
levels Planning/Design 2024-2035 $60M To be determined CEQAmRWCQB 60,000 Water Supply
Enhancement
Project - Direct
Recharge
Direct Recharge SEWD Groundwater
levels Design 2024-2030 To be determined
To be
determined Not determined To Be Determined
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-11
Projects and Management Actions November 2024
Project Name Project Type Project
Proponent
Measurable
Objective
Expected to
Benefit
Current Status
Time-table
(initiation and
completion)
Estimated
Capital Cost
Estimated
Annual O&M
Cost
Required
Permitting and
Regulatory
Process1
Maximum
Recharge
Benefit
(AF/year)
SSJID Water
Master Plan -
System
Improvements
In-Lieu Recharge SSJ GSA Groundwater
levels
Feasibility study
complete 2023-2040 $ 30 – 40 M To be determined Not determined 15,000 Total Category B 509,985
1 Acronyms defined: Stockton East Water District (SEWD), Central San Joaquin Water Conservation District (CSJWCD), North San Joaquin Water Conservation District (NSJWCD), California Department of Fish and Wildlife (DFW), Central Valley Flood Protection Board (CVFPB), Regional Water Quality Control Board (RWQCB), and U.S. Army Corps of Engineers (USACE), State Water Resources Control Board (SWRCB), California Environmental Quality Act (CEQA), U.S. Bureau of Reclamation (USBR), National Pollutant Discharge Elimination System (NPDES), Waste Discharge Requirements (WDR).

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-12
Projects and Management Actions November 2024
Figure 6-1: Location of Category A Projects
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-13
Projects and Management Actions November 2024
Figure 6-2: Location of Category B Projects

6.2.4 Category A Projects
As previously mentioned, Category A Projects are projects that were completed by 2024 or are anticipated to advance in the next five years and have existing water rights or agreements. The projected supply of projects in this category will be considered as offsetting the projected 2040 supply imbalance. Up to 154,900 AF/year of water is expected to be recharged in Wet years as a result of implementation of the Category A projects.

6.2.4.1 Lake Grupe In-Lieu Recharge
The Lake Grupe In-Lieu Recharge Project, proposed by SEWD, is to construct a surface water diversion turn-out on the Calaveras River, upstream of Bellota, and to supply surface water to multiple farms/growers currently using groundwater. The proposed project is to allow 2,500 acres of orchard crops to irrigate with surface water from Lake Grupe instead of using groundwater. Lake Grupe is at the end of rolling hills fed by two or more natural episodic streams. The proposed project would pump water from the Calaveras River, transport the water in a 24-inch PVC EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-14
Projects and Management Actions November 2024
pipeline for about 5,000 feet, with an elevation gain of 170 feet through private properties, discharge the water into one of the ravines feeding Lake Grupe, and then the surrounding growers would pump the water from the Lake for irrigation.

The diverted water would flow through a ravine, currently on private lands, and recharge the groundwater basin underneath. The benefit of this project is the in-lieu banking of 7,000 AF of groundwater from irrigation conversion plus additional 13,000 AF of percolation in the ravine.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: In-lieu Recharge
Estimated Groundwater Offset and/or Recharge: 2,000 - 4,900 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: This project has been completed.

Required Permitting and Regulatory Process: This project requires the installation of a new intake in the Calaveras River and construction of a pipeline through private properties. The installation of a new intake in the Calaveras River would require permits from California Department of Fish and Wildlife (DFW), Central Valley Flood Protection Board (CVFPB), Regional Water Quality Control Board (RWQCB), and U.S. Army Corps of Engineers (USACE).

Time-table for Initiation and Completion: Construction on the project was completed in 2023.

Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. This project is anticipated to offset up to 4,900 AF/year in groundwater pumping in SEWD. Benefits to groundwater levels will be evaluated through Eastern San Joaquin Water Resources Model (ESJWRM) model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The surface water source of this proposed project is from SEWD’s existing contract with the U.S. Bureau of Reclamation (USBR) for the New Hogan Reservoir. Surface water is diverted from the Calaveras River. This is an existing surface water right.

Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $2.3 million in capital costs and $330,000 in annual operations and maintenance costs. Costs for this project will be met through SEWD District staffing and District rates to establish new accounts.

Circumstances for Implementation: Construction for this project has been completed.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Not applicable; this project has been constructed.

6.2.4.2 SEWD Surface Water Implementation Expansion
As part of the SEWD Surface Water Implementation Expansion Project, SEWD would require landowners adjacent to surface water conveyance systems (rivers or pipelines) to utilize surface water as part of the SGMA implementation.

This would increase surface water usage by about 18,000 to 20,000 AF/year with in-lieu groundwater recharge benefits.

Currently, there are about 6,000 acres irrigated with groundwater that could be converted to surface water. There are also an additional 1,500 acres with inactive surface water accounts. SEWD would be the lead agency in EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-15
Projects and Management Actions November 2024
environmental/CEQA review and would assist landowners/growers in establishing a turnout for agricultural irrigation and acquiring necessary permits through federal and state regulatory agencies.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: In-lieu Recharge
Estimated Groundwater Offset and/or Recharge: 4,000 – 19,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: This project is currently being implemented in phases. The District converted 2,505 acres to surface water and is in the planning phase to convert an additional 1,135 acres.

Required Permitting and Regulatory Process: The required permitting for this project would include acquiring permits/approvals from California DFW, RWQCB, CVFPB, and USACE by private landowners/diverters. SEWD would be the lead agency for CEQA review and would assist landowners/diverters in obtaining the permits.

Time-table for Initiation and Completion: This project is expected to begin in 2019 and be on-going, with benefits accrued by 2029.

Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. This project is anticipated to offset up to 19,000 AF/year in groundwater pumping in SEWD. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project relies on water from New Hogan Reservoir (Calaveras River water) and New Melones Reservoir (Stanislaus River water). This is an existing surface water right.

SEWD has long-term water supply contracts with USBR for both New Hogan Reservoir and New Melones Reservoir.

Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $750,000 in capital costs and $100,000 in annual operations and maintenance costs. Costs for this project will be met through staffing and rates for new accounts.

Circumstances for Implementation: This project is currently being implemented in phases. As scenarios change, the project can come online to bring additional resources for adaptive management. Implementation of the project will be based on long-term management or changing needs of the GSA or Subbasin.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring currently moving forward.

6.2.4.3 White Slough Water Pollution Control Facility Expansion This project would include the construction of a 70-acre pond expansion with a storage capacity of 388 AF. The purpose of this project is to provide tertiary-treated Title-22 effluent for use as irrigation water on approximately 890 acres of agricultural land surrounding the White Slough Water Pollution Control Facility (WPCF) to offset groundwater pumping.

This project is estimated to reduce the annual volume discharged to Dredger Cut (a dead-end slough of the Sacramento-San Joaquin River Delta) by approximately 160 to 210 million gallons. Flow will be diverted from Dredger Cut at a rate up to 1,700 gallons per minute over an approximate 75- to 90-day period between October 1 and May 31 EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-16
Projects and Management Actions November 2024
of each year. Project studies have demonstrated that the storage provided by this project will significantly offset groundwater pumping through in-lieu use.

Project Summary
Submitting GSA: City of Lodi
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: 3,700 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by providing direct groundwater recharge opportunities.

Project Status: Construction of this project has been completed. In WY 2023, 518 AF of direct recharge was provided by this project. Roughly 3,700 AF/year of percolation recharge is expected. Additionally, the tertiary treated wastewater will be used to irrigate the on-site agricultural fields, thereby reducing groundwater pumping for irrigation.

Required Permitting and Regulatory Process: The permitting and regulatory processes required for this project have been completed.

Time-table for Initiation and Completion: Construction of this project has been completed.

Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. This project is anticipated to offset approximately up to 3,700 AF/year in groundwater pumping in the City of Lodi. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project will rely on the use of recycled water, in the form of tertiary-treated Title 22 effluent form the White Slough WPCF Expansion. No additional water source will be utilized for this project.

Legal Authority: The City of Lodi has legal authority to administer this project through Water Code §71000-73000.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $6 million in capital costs and $4,664 in annual operations and maintenance costs. This project will be financed through the DWR Proposition 84 Grant Funding Program.

Circumstances for Implementation: The construction of this project has been completed. Implementation of the project will be based on long-term management or changing needs of the GSA or Subbasin.

Trigger for Implementation and Termination: There is no plan to terminate this project, as it has been completed and the operations and maintenance cost is minimal.

Process for Determining Conditions Requiring the Project have Occurred: Not applicable, this is a Category A project that is currently moving forward.

6.2.4.4 CSJWCD Capital Improvement Program
CSJWCD assists users to convert groundwater fields to surface water use. The user applies for water credits based upon new surface water acres. The user is responsible for constructing a diversion facility. As water is diverted the District reduces the water charge until credit is used or seven years since implementation have elapsed. The Capital Improvement Program has been on-going since 1996.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-17
Projects and Management Actions November 2024
Project Summary
Submitting GSA: Central San Joaquin Water
Conservation District
Project Type: In-lieu Recharge
Estimated Groundwater Offset and/or Recharge: 0 - 24,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: This project has been implemented and is on-going each year with available water delivery.

Required Permitting and Regulatory Process: CSJWCD is not required to comply with permits or regulatory processes to implement and oversee the Capital Improvement Program. However, individual applicants are required to have approval of the CSJWCD Board of Directors and may be required to obtain streambed alteration permits.

Time-table for Initiation and Completion: The Capital Improvement Program has been on-going since 1996. New individual projects are anticipated to begin each year. Individual applicants are expected to complete their projects 7 years after initiation.

Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. This project is anticipated to offset up to 24,000 AF/year in groundwater pumping in CSJWCD. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. This project is anticipated to offset up to 24,000 AF/year in groundwater pumping in CSJWCD. Benefit to the groundwater aquifer has already accrued and will continue to accrue as new projects are implemented. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project relies on this use of surface water from the New Melones Unit Central Valley Project. The surface water source is based upon a contract with the United States for delivery of surface water from the New Melones Unit of the Central Valley Project. The contract is longterm; however, water availability is subject to drought conditions. This is an existing water right.

Legal Authority: The Water Code, Division 21 §74000 et seq. authorizes CSJWCD to acquire, sell, and distribute water and fix rates for service throughout the District.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $50,000 in annual operations and maintenance costs. This project provides for the payment of delivered surface water at a reduced rate. Any deficit in cost of water is recovered by full cost of surface water to other users, groundwater extraction fees, and acre assessments.

Circumstances for Implementation: This project has been implemented and continues move forward. As scenarios change, the project can be adapted to bring additional resources for adaptive management. Implementation of the project will be based on long-term management or changing needs of the GSA or Subbasin.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Not applicable; this is a Category A project that is currently in operation.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-18
Projects and Management Actions November 2024

6.2.4.5 NSJWCD South System Modernization
This project will modernize the South System Pump and Distribution System to facilitate delivery of 9,000 AF/year of additional surface water to farmers in-lieu of groundwater pumping. Water would come from NSJWCD Permit 10477 supplies, which are available in about 55 percent of years.

Project Summary
Submitting GSA: North San Joaquin Water
Conservation District
Project Type: In-lieu Recharge
Estimated Groundwater Offset and/or Recharge: 0 - 10,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: This Project is progressing. Phase 1 was completed in 2019-2021 and included a new pump station, variable frequency drive (VFD), meters, automation equipment, SCADA, and a new main junction box at Tretheway and Brandt Roads. Phase 2 was completed in early 2024 and included new sections of the main pipeline and the addition of meters and SCADA. ID3A, formed in 2021 for construction of the Pixley lateral, was completed in 2022.

NSJWCD is working on the formation of ID3B for the Handel lateral for which NSJWCD received $1M federal grant.

Additionally, NSJWCD was just awarded a $3M IRWM grant for Phase 3 South System improvements to focus on more mainline replacements and increased groundwater recharge capacity. Phase 3 was awarded in 2024 and will be constructed in 2024-25. NSJWCD applied for a $3M WaterSmart Grant for Phase 4. Future phases will include additional laterals and recharge capacity along the south system to expand capacity to take additional wet year water for recharge, including MICUP water.

Required Permitting and Regulatory Process: All permits for the pump station work have been obtained. Minor grading and road encroachment permits may be needed for on-going work to the distribution system.

Time-table for Initiation and Completion: This project began in 2018. Phases 1,2,3, and the Pixley and Handel Laterals are expected to be completed by 2025. Phase 4 is expected to begin by 2025 and be completed by 2028, with future phases anticipated from 2028-2035.

Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. Phases 1-4 of this project are anticipated to offset up to 10,000 AF/year in groundwater pumping in NSJWCD, with future phases offsetting an additional 15,000 AF/year. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project relies on surface water from NSJWCD Permit 10477 (Mokelumne River water). This is an existing surface water right.

Legal Authority: The legal authority for this project is covered under Water Code §74000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $7 million in capital costs and $200,000 in annual operations and maintenance costs for Phases 1 & 2; $4 million in capital costs and $200,000 in annual operations and maintenance costs for Phase 3; $13 million in capital costs and $200,000 in annual operations and maintenance costs for Phase 4, and $10-20 million in capital costs and $200,000 in annual operations and maintenance costs for future phases. Costs for this project will be met through grant funding, landowner assessments, district property taxes, and water charges.

Circumstances for Implementation: This project is currently moving forward. As scenarios change, the full project can come online to bring additional resources for adaptive management.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-19
Projects and Management Actions November 2024
Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Not applicable, this is a Category A project that is currently moving forward.

6.2.4.6 Long-Term Water Transfer to SEWD and CSJWCD
Oakdale Irrigation District (OID) and South San Joaquin Irrigation District (SSJID) have historically participated in longterm water transfers of surplus, pre-1914, surface water rights to other entities within the Eastern San Joaquin Subbasin. These transfers have included one-year transfers to CSJWCD, as well as a nearly 10-year transfer to SEWD for both agricultural and urban purposes. The most recent transfer with SEWD occurred in 2019. These areas of the Subbasin have surface water available from the USBR’s Central Valley Project; however, project water allocations become significantly reduced in below normal and dry water years. When surface water is not available, many of the agricultural customers in these areas have typically turned to groundwater in order to meet their annual and permanent crop water demands. Providing long-term water transfers from OID/SSJID to other agencies within the Subbasin would allow for increased average annual surface water deliveries to the Subbasin area, reducing groundwater reliance and overdraft within the Subbasin, especially during drought years. SEWD and CSJWCD overlie a significant portion of the Subbasin dependent on groundwater and subject to historical overdraft conditions.

No new facilities would need to be constructed to convey water from OID/SSJID to SEWD, and CSJWCD receives water through diversions from a tunnel just upstream of the OID/SSJID owned Goodwin Dam on the Stanislaus River.

Historical transfers have been accomplished through the use of these existing facilities. Additional infrastructure may be necessary to increase distribution of surface water supplies to irrigated agriculture and to achieve adequate improvement toward sustainability goals.

Project funding could be provided directly from the districts participating in the water transfers. Additional infrastructure to promote additional surface water use and capital payments for surface water transfers could be provided indirectly by groundwater reliant entities, thereby providing a means of continuing to utilize groundwater while investing in a Subbasin-wide project that assures continued sustainability within the Subbasin.

Project Summary
Submitting GSA: South San Joaquin GSA
Project Type: Intrabasin Transfer/In-lieu
Recharge
Estimated Groundwater Offset and/or Recharge: Up to 20,000 AF/year Other Participating Entities: Oakdale Irrigation District, Stockton East Water District,
Central San Joaquin Water
Conservation District
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: No design is needed for this project, as the infrastructure is in place. Environmental review may need to be completed.

Required Permitting and Regulatory Process: This project must comply with CEQA. Temporary transfers may have less rigorous permitting requirements.

Time-table for Initiation and Completion: A 10-year water transfer project was approved by SEWD, OID, and SSJID in April 2023. Transfers from OID/SSJID to SEWD/CSJWCD have historically been agreed to, with historical transfer amounts varying from 0 to 40,000 AF/year.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-20
Projects and Management Actions November 2024
Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. This project is anticipated to offset up to 20,000 AF/year in groundwater pumping in SEWD and CSJWCD. Benefits to groundwater levels will be evaluated through ESJWRM model simulations. Participating districts would report annually the amount agreed to be transferred and the amount diverted under transfer.

How Project Will Be Accomplished/Evaluation of Water Source: OID and SSJID hold pre-1914 water rights on the Stanislaus River. USBR is junior in right to OID and SSJID. This is an existing surface water right.

Legal Authority: OID and SSJID are irrigation districts formed in accordance with State law and hold pre-1914 water rights on the Stanislaus River. SEWD and CSJWCD are water conservation districts also formed in accordance with State law. Historically, water transfers occurring between OID/SSJID and SEWD/CSJWCD are approved by mutual agreement.

Estimated Costs and Plans to Meet Costs: Costs for this project are estimated at up to $9 million annually ($200 per acre-foot for agricultural use, and $300 per acre-foot for urban). Costs for this project will be met by recipients of water or groundwater pumping benefit.

Circumstances for Implementation: This project is currently moving forward. As scenarios change, the project can bring additional resources for adaptive management. Implementation of the project will be based on long-term management or changing needs of the GSA or Subbasin. Short-term transfers are expected to occur on an as-needed basis.

Trigger for Implementation and Termination: Transfers may take place upon mutual agreement. Termination would be subject to the terms of the agreement if applicable.

Process for Determining Conditions Requiring the Project have Occurred: Not applicable; this is a Category A project that is currently underway.

6.2.4.7 South System Groundwater Banking with EBMUD
NSJWCD, East Bay Municipal Utility District (EBMUD), and other entities in San Joaquin County entered into a Protest Dismissal Agreement (the “PDA”) in 2014 to resolve various water right protests. The PDA Agreement includes a commitment to undertake a pilot-level groundwater banking project and a longer-term groundwater banking project.

The pilot level banking project is called the “DREAM” project and is now complete. The DREAM project involved the delivery of 1,000 AF of EBMUD water into the NSJWCD service area along the South System to use for irrigation, effectuating 1,000 AF of in-lieu groundwater recharge. EBMUD received a banked water credit of 50 percent of the amount of water recharge, not to exceed 500 AF. EBMUD withdrew the banked water between January and April of 2024. NSJWCD controlled the withdrawal of the banked water by pumping groundwater from a well that is centrally located in the area of recharge and then conveyed the pumped groundwater to the EBMUD Mokelumne Aqueduct.

The extraction and return of the banked water were subject to a San Joaquin County groundwater export permit. The permit placed additional conditions and restrictions on the extraction of the banked water, including a 5 percent per year annual loss factor and pumping restrictions to prevent impacts to other groundwater users.

EBMUD and NSJWCD have started the preliminary planning for the longer-term banking project. The longer-term banking project may use the same concept as the pilot project but will involve larger quantities of water and potential additional facilities to deliver and use the water for in-lieu recharge and potentially direct recharge within the NSJWCD service area, and to extract and return banked water credits to EBMUD. The longer-term project contemplates EBMUD providing surface water supplies of 3,000 AF/year to 6,000 AF/year in dry years and 8,000 AF/year in wet years to NSJWCD. These surface water supplies would come from EBMUD’s water rights on the Mokelumne River and would be in addition to surface water available under NSJWCD’s water right. EBMUD would receive a banked water credit for 50 percent of the additional supplies provided, leaving a net surface/groundwater increase to the NSJWCD area of 50 percent of all additional supplies provided.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-21
Projects and Management Actions November 2024
The PDA also provides that the wet year water supplies could be used by SEWD for groundwater banking if they cannot be used in NSJWCD.

Project Summary
Submitting GSA: North San Joaquin Water
Conservation District
Project Type: In-lieu Recharge
Estimated Groundwater Offset and/or Recharge: 0 - 4,000 AF/year Other Participating Entities: East Bay Municipal Utility District, Eastern Water Alliance,
San Joaquin County and
Stockton East Water District
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: The demonstration portion of the project is complete. Parties need to finalize design, perform environmental review, and obtain necessary permits to operate the permanent project.

Required Permitting and Regulatory Process: The permanent project requires a SWRCB Change Petition for Permit 10478, a San Joaquin County Groundwater Export Permit, and regulatory permits as needed for facilities such as pipelines.

Time-table for Initiation and Completion: The pilot Dream Project was completed in April 2024. A larger project is currently in the planning stages, with implementation expected by 2030.

Expected Benefits and Evaluation: Subbasin groundwater recharge through the in-lieu use of alternate water supply will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. This project is anticipated to offset 4,000 AF/year in groundwater pumping in NSJWCD. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project would use water supplies from EBMUD Permit 10478 (Mokelumne River water). This is an existing surface water right. EBMUD has a right tied to hydrology, with amounts set by contract.

Legal Authority: The legal authority for this project is covered under Water Code §74000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $5 million in capital costs and $400,000 in annual operations and maintenance costs. Costs for this project will be met by grant funding, banking fees, and water charges.

Circumstances for Implementation: This project is anticipated to move forward. As scenarios change, the project can come online to bring additional resources for adaptive management. Implementation of the project will be based on long-term management or changing needs of the GSA and their partners or Subbasin. Short-term transfers are expected to occur on an as-needed basis.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: The pilot portion of this project has been completed. Implementation of this project will be based on long-term management or changing needs of the GSA and their partners and/or Subbasin.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-22
Projects and Management Actions November 2024

6.2.4.8 NSJWCD North System Modernization/Lakso Recharge Project This project will repair, upgrade, and modernize the North System Pump and Distribution System to facilitate delivery of 4,000 to 6,000 AF/year of surface water to farmers in-lieu of groundwater pumping and direct recharge. Water would come from NSJWCD Permit 10477 supplies, which are available in about 55 percent of years. Average deliveries would vary around 1,000 AF/year to 4,000 AF/year in about half of the years. In addition, there is a small, sandy recharge pond location on the Lakso property located along the upper portion of the North System pipeline along Tretheway Road. The pond is about 2 acres in size and can recharge about 2 AF/day. The Lakso Project is under negotiations for expansion as the landowner recently removed 160 acres of vineyards with no immediate plans to replant. Capacity could expand to over 6 AF/day year-round if negotiations are successful. NSJWCD could convey water through the NSJWCD North System, to the Lakso recharge pond, to directly recharge surface water during times that water is available but there is not irrigation demand, such as during the December through May time period or during the interim period of years before the remainder of the North System pipeline is repaired or replaced.

Project Summary
Submitting GSA: North San Joaquin Water
Conservation District
Project Type: In-lieu Recharge/Direct
Recharge
Estimated Groundwater Offset and/or Recharge: 0 - 4,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu and direct recharge opportunities.

Project Status: This first phase (Phase 1A) of this project has been completed and is operational. Phase 1B is under construction, and Phase 2 is in the planning stages.

Required Permitting and Regulatory Process: This project would require regulatory permitting as needed for minor construction related to rehabilitation of existing water delivery infrastructure.

Time-table for Initiation and Completion: This project began in 2021 and is anticipated to be completed by 2026.

Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and critical to establishing long-term Subbasin sustainability. This project is anticipated to offset 4,000 AF/year in groundwater pumping in NSJWCD. In addition, there are opportunities to directly recharge surface water to the groundwater basin at specified times. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project would use water supplies available through NSJWCD Permit 10477 (Mokelumne River water). This is an existing surface water right.

Legal Authority: The legal authority for this project is covered under Water Code §74000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $7 million in capital costs and $150,000 in annual operations and maintenance costs. Costs for this project will be met by grant funding, landowner assessments, district property taxes, and water charges.

Circumstances for Implementation: This project is currently moving forward. As scenarios change, the project can bring additional resources for adaptive management. Short-term transfers are expected to occur on an as-needed basis.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation this project is phased and is currently underway.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-23
Projects and Management Actions November 2024

6.2.4.9 Tecklenburg Recharge Project
This project involved the construction and operation of a 10-acre recharge pond on the south side of the Mokelumne River on property purchased by NSJWCD from the Tecklenburg family. NSJWCD is using Permit 10477 water available during December 1 through June 30, and not needed for irrigation, for recharge. This project could recharge up to 2,000 AF/year in years when water is available. Because this project can use water available during the direct diversion flood season, water is expected to be available more frequently under the NSJWCD water right for this project, or 80 percent of years. Capital costs include the purchase of the 10-acre property for this project.

Project Summary
Submitting GSA: North San Joaquin Water
Conservation District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: 0 - 2,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: This project is substantially complete. NSJWCD acquired a 10-acre parcel in 2023 and has constructed and operated the recharge basin since July 2023. NSJWCD is currently working on a new lateral from the South System mainline which would increase the project’s capacity.

Required Permitting and Regulatory Process: This project would require CEQA review and a possible grading permit.

Time-table for Initiation and Completion: This project was substantially completed in 2024.

Expected Benefits and Evaluation: This project is anticipated to directly recharge up to 2,000 AF/year to the groundwater basin in NSJWCD. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project would use water supplies available through NSJWCD Permit 10477 (Mokelumne River water). Once Permit 10477 supplies are fully committed to in-lieu recharge projects, NSJWCD could apply to appropriate Mokelumne River flood flows for this direct recharge project. This is an existing surface water right.

Legal Authority: The legal authority for this project is covered under Water Code §74000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $1 million in capital costs and $400,000 in annual operations and maintenance costs. Costs for the current project will be met by water charges.

Funding for additional phases has not been identified at this time.

Circumstances for Implementation: This project is currently substantially complete. As scenarios change, the project can be adapted to bring additional resources online. Implementation of the project will be based on long-term management or changing needs of the GSA or Subbasin and availability of surface water.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project is ongoing.

6.2.4.10 City of Stockton Phase 1: Groundwater Recharge Project This project involves the development of a groundwater recharge and recovery operation adjacent to the Delta Water Treatment Plant. The project would enhance the City of Stockton’s water supply reliability by allowing for the direct recharge of surface water into the underlying groundwater basin. This project received a 2022 SGMA Implementation Round 1 grant for $250,000 to conduct a geotechnical investigation of the recharge site to determine the suitability of EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-24
Projects and Management Actions November 2024
the site for groundwater recharge and recovery. A feasibility study was completed in December 2023 and determined a recharge potential of approximately 22,000 AFY.

A feasibility memorandum completed in 2009 that estimated that Mokelumne River water purchased from WID, along with stormwater from the City of Lodi available via the Wilkerson Lateral could be utilized for recharge purposes. An estimated amount of up to 6,500 AFY between March 1 and October 15 would be available from WID, with water assumed to be available only during water year types that are “Wet” or “Above Normal.” Additionally, Lodi stormwater is a potential source for groundwater recharge and an estimated 1,545 AFY is available mostly during winter months when precipitation occurs. The estimated recharge rate at the site was 0.8 AF/day.

In order to expand the use of Permit 21176 water, City of Stockton’s water supply from the San Joaquin River could also be utilized. With an assumed infiltration pond size of 70 acres and a wetted period of 228 days, an estimated 12,768 AFY could potentially be stored to the groundwater basin. Though if water was available during only a 90-day application period, the potential recharge volume would be 5,040 AFY. In the City of Stockton’s water rights petition2, an annual total of 5,102 AFY was estimated to be available for groundwater banking with zero in April through June.

As assumed in the feasibility study, if the recharge system can be used four times per year, than the project could provide approximately 20 TAF of recharge annually. Though this project has been called groundwater banking in the past, there are no firm plans to extract water and no more water would be extracted than was recharged. A more detailed technical analysis of the timing and quantity of water supply will be conducted in the future.

Due to the varying sources of water supply that may be available for recharge (WID water, Lodi stormwater, and Stockton water), water is expected to be able to be recharged year-round.

Project Summary
Submitting GSA: City of Stockton
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: 20,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: A feasibility study for this project was completed in December 2023. The design is in progress and construction of the recharge basins will begin in spring 2025.

Required Permitting and Regulatory Process: This project would require CEQA review.

Time-table for Initiation and Completion: This project is anticipated to be completed by 2026.

Expected Benefits and Evaluation: This project is anticipated to provide water for direct recharge in the critically overdrafted subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: Delta Water Treatment Plant Legal Authority: The City of Stockton has legal authority to administer this project through Water Code §71000-73000.

Estimated Costs and Plans to Meet Costs: The estimated capital costs for this project are $11,500,000.

Circumstances for Implementation: This project is currently moving forward. As scenarios change and the project progresses, the project can come online to bring additional resources for adaptive management. Implementation of the project will be based on long-term management or changing needs of the GSA or Subbasin.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project is ongoing.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-25
Projects and Management Actions November 2024

6.2.4.11 West Groundwater Recharge Basin
The West Groundwater Recharge Basin will provide additional opportunities for direct recharge of surface water into the underlying groundwater basin. Between 1,500 and 16,000 acre-feet per year may be available for direct recharge, depending on available water. Due to the varying sources of water for the project (surface water and stormwater runoff), the project is anticipated to be able to recharge project water year-round.

This project relies on water from New Hogan Reservoir (Calaveras River water) and New Melones Reservoir (StanislausRiverwater). This is an existing surfacewaterright.SEWDhas long-termwater supply contracts with USBR for both New Hogan Reservoir and New Melones Reservoir. In addition to Calaveras River and Stanislaus River water, stormwater runoff will also contribute to the volume of water available for recharge. Water would be recharged at a recharge basin located near SEWD’s water treatment plant.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: 1,500 - 16,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: Construction on the project started in 2024.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: This project is anticipated to be completed by 2032.

Expected Benefits and Evaluation: This project is anticipated to provide water for direct recharge in the critically overdrafted subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project relies on water from New Hogan Reservoir (Calaveras River water) and New Melones Reservoir (Stanislaus River water). This is an existing surface water right.

SEWD has long-term water supply contracts with USBR for both New Hogan Reservoir and New Melones Reservoir.

Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project are unknown at this time. USACE is paying SEWD for soil excavation costs. The remainder of the project will be funded by SEWD or additional grant funds.

Circumstances for Implementation: This project is currently moving forward. As scenarios change, the project can come online to bring additional resources for adaptive management. Implementation of project will be based on long-term management or changing needs of the GSA or Subbasin.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Construction of the project has begun.

Implementation of this project will ultimately be based on long-term management or changing needs of the GSA or Subbasin.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-26
Projects and Management Actions November 2024

6.2.4.12 NSJWCD Private Pump Partnerships
This project involves agreements between NSJWCD and existing riparian pumpers along the Mokelumne River to use their existing pumps to pump NSJWCD’s Permit 10477 water for delivery to adjacent non-riparian lands or recharge basins/on-farm recharge. This project leverages existing infrastructure to achieve increased surface water use and reduced groundwater pumping in the district. NSJWCD is implementing this project for one landowner in 2024 to irrigate 200 acres and plans to add an additional 200 acres each year for five years.

Since the project plans to add an additional 200 acres every year, by 2030 there will be an estimated 1,000 acres of land receiving surface water from private pumps. The estimated volume of water for 1,000 acres is 1,500 AFY in normal years and 3,000 AFY in wet years. The project is not expected to run in drought or dry years.

Project Summary
Submitting GSA: North San Joaquin Water
Conservation District
Project Type: In-lieu/ Direct Recharge
Estimated Groundwater Offset and/or Recharge: 0 - 3,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu and direct recharge opportunities.

Project Status: The first phase of this project was completed in early 2024. NSJWCD is planning to add an additional 200 acres each year for 5 years.

Required Permitting and Regulatory Process: A Minor Change Petition was submitted to the State in 2024 and is awaiting approval.

Time-table for Initiation and Completion: The first phase of this project was completed in 2024 and is anticipated to be completed by 2030.

Expected Benefits and Evaluation: This project is anticipated to provide water for in-lieu and direct recharge in the critically overdrafted subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project relies on water from the Mokelumne River.

This is an existing surface water right held by NSJWCD (Permit 10477).

Legal Authority: The legal authority for this project is covered under Water Code §74000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project are unknown at this time. Costs will be met by District general revenue sources, and individual landowner contributions.

Circumstances for Implementation: This project is currently moving forward. As scenarios change, the project can be expanded to bring additional resources for adaptive management. Implementation of the project will be based on longterm management or changing needs of the GSA or Subbasin.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project has begun; subsequent phases will be based on long-term management or changing needs of the GSA or Subbasin.

6.2.4.13 Oakdale Irrigation District In-lieu and Direct Recharge Project The Oakdale Irrigation District In-lieu and Direct Recharge Project is intended to be a cooperative long-term project between OID and landowners to the east of OID’s boundaries within the East Side San Joaquin GSA. The purpose EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-27
Projects and Management Actions November 2024
of this project is to allow OID to facilitate surface water deliveries for in-lieu use or direct recharge for East Side San Joaquin GSA landowners during times and conditions that will not impact OID’s existing agricultural customers.

The project envisions the development of up to approximately 25,000 AF of surface water from the Stanislaus River being made available to landowners east of OID’s service area boundaries in both the Eastern San Joaquin and Modesto Subbasins in all, except Critically Dry, water years. Water deliveries would occur through a limited number of existing and newly constructed private irrigation conveyance infrastructure for use between March 1st and September 30th. Some direct recharge is expected to occur from the project as canal or reservoir seepage in the conveyance network. OID surface water will not be delivered as part of the project between October 1st and March 1st. The OID Board of Directors will continue to consider and define the volume of water (if any) available to this Project on an annual basis in non-Critically Dry water years.

The OID 10-Year out-of-District Water Sales Program (10-Year Program) began in 2023 and includes 4,292 irrigated acres in the Eastern San Joaquin Subbasin within the East Side San Joaquin GSA. Under the 10-Year Program, participating landowners are required to purchase a minimum of 1.5 acre-feet per irrigated acre when surplus surface water is available from OID resulting in a minimum of 6,438 acre-feet being purchased each year. The landowners also have the opportunity to purchase and use additional surplus surface water throughout the irrigation season if available.

Project Summary
Submitting GSA: Oakdale Irrigation District
Project Type: In-lieu/ Direct Recharge
Estimated Groundwater Offset and/or Recharge: 0 - 25,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu and direct recharge opportunities to out-of-district lands in the Subbasin.

Project Status: The project is ongoing.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: The project began in 2023 and is anticipated to be completed by 2032.

Expected Benefits and Evaluation: This project is anticipated to provide water for in-lieu and direct recharge in the critically overdrafted subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: Surface water from Stanislaus River Legal Authority: The legal authority for this project is covered under Water Code §20500 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project are unknown at this time. Landowners participating in the 10-year program are responsible for the costs of new turnouts, private conveyance systems, and surplus surface water purchased for out-of-district irrigation.

Circumstances for Implementation: This project is currently moving forward. As scenarios change, the project can come online to bring additional resources for adaptive management. Implementation of the project will be based on long-term management or changing needs of the GSA, its growers, or Subbasin.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project will be based on long-term management or changing needs of the GSA or Subbasin.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-28
Projects and Management Actions November 2024

6.2.4.14 City of Stockton Advanced Metering Infrastructure The City of Stockton Municipal Utilities Department (MUD) provides treated drinking water through approximately 48,000 water meters, of which a portion are read via a touch-read system and the remainder are read manually by staff every month. Manual meter reading is the least efficient method of meter reading and the costliest. AMI using improved technology is far more efficient and generally very cost effective when compared to manual reading. AMI also provides several other benefits beyond simple cost savings including improved customer service, leak detection, and real-time consumption information to the customer. Documented customer water savings and improved demand-side water conservation has occurred when real-time consumption information is available.

This project would apply AMI to water meters in the City of Stockton Service Area. Improved technology would increase efficiency and decrease costs associated with manual reading. Additional benefits beyond cost savings include improved leak detection and demand-side water conservation.

Project Summary
Submitting GSA: City of Stockton
Project Type: Conservation
Estimated Groundwater Demand Reduction: 2,000 AF/year
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing demand-side water conservation opportunities.

Project Status: An initial study for this project was completed in 2011. The contract for this project was awarded in March 2024, and is anticipated to be completed by 2028.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not yet been determined.

Time-table for Initiation and Completion: This project will be completed by 2028.

Expected Benefits and Evaluation: This project is anticipated to reduce groundwater demand by 2,000 AF/year in the City of Stockton through leak detection and real-time consumption information to the customer. Benefits to groundwater levels will be evaluated by quantifying resulting demand reduction.

How Project Will Be Accomplished/Evaluation of Water Source: This project is a demand-side conservation project. No additional water source will be utilized for this project.

Legal Authority: This project would be under the authority of the City of Stockton and implemented within the service area.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $17 million in capital costs and $550,000 in annual operations and maintenance costs. Costs for this project would be met by ratepayers and through grants or other funding sources.

Circumstances for Implementation: This project is currently moving forward. As scenarios change, the project can be expanded to bring additional resources for adaptive management. Implementation of the project will be based on longterm management or changing needs of the GSA or Subbasin.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project will be based on long-term management or changing needs of the GSA or Subbasin.

6.2.5 Category B Projects
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-29
Projects and Management Actions November 2024
Category B projects are defined as projects that are not anticipated to advance in the next five years, but may be implemented in the future, particularly if Category A projects do not fully achieve stated recharge and/or offset targets or do not produce a response as simulated in the model. Together these projects result in a total maximum benefit of 509,985 AF/year in groundwater offset/recharge/conservation that could potentially be made available to the Subbasin if funding and water rights are secured.

6.2.5.1 City of Manteca Advanced Metering Infrastructure The City of Manteca provides treated drinking water through approximately 20,696 service connections. In order to improve the efficiency and reliability of water meters, the City has been replacing existing meters and upgrading the Encoder Receiver Transmitters (ERTs) on meters when required. The ERTs and new meters allow for remote reading of flows via a radio signal to a radio receiver inside a city vehicle or at a fixed location. The City also plans to construct the infrastructure for an Advanced Metering Infrastructure (AMI) network to further increase efficiency. AMI also provides several other benefits beyond simple cost savings including improved customer service, leak detection, and real-time consumption information to the customer. Documented customer water savings and improved demand-side water conservation has occurred when real-time consumption information is available.

This project would apply advanced metering infrastructure to water meters in the City of Manteca service area.

Improved technology would increase efficiency and decrease costs associated with manual reading. Additional benefits beyond cost savings include improved leak detection and demand-side water conservation.

Project Summary
Submitting GSA: City of Manteca
Project Type: Conservation
Estimated Groundwater Demand Reduction: 272 AF/year
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing demand-side water conservation opportunities and reducing pumping.

Project Status: This project is currently experiencing delays due to higher priority projects needed.

Required Permitting and Regulatory Process: There are no permitting or regulatory requirements for this project at this time.

Time-table for Initiation and Completion: This project has experienced delays due to higher priority projected needed.

The project’s implementation will continue once funding is available.

Expected Benefits and Evaluation: This project is anticipated to reduce groundwater demand by 272 AF/year in the City of Manteca through leak detection and real-time consumption information to the customer. Benefits to groundwater levels will be evaluated by quantifying resulting demand reduction.

How Project Will be Accomplished/Evaluation of Water Source: This project is a demand-side conservation project. No additional water source will be utilized for this project.

Legal Authority: This project is under the authority of the City of Manteca and implemented within the City’s service area.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $650,000 in capital costs and $300,000 in annual operations and maintenance costs. The AMI Project is a Capital Improvement Project; however, funding is currently not available due to the need for higher priority projects.

Circumstances for Implementation: The City of Manteca has started to implement the AMI infrastructure in phases by purchasing meters that have the capability to be read remotely. Installation of other components, like fiber optic cable and radio tower antennas, is in the planning stage.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-30
Projects and Management Actions November 2024
Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Not applicable; this project is currently in the planning stage.

6.2.5.2 City of Lodi Surface Water Facility Expansion & Delivery Pipeline This project would extend the filter room at the City of Lodi Surface Water Facility and add an additional 10 million gallons per day (MGD) capacity of surface water treatment. In addition to the filter room extension, the City will construct a second sedimentation basin and add pumps throughout the facility to handle the additional volume of water being moved. This project also includes an extension of the 36-inch transmission pipeline leaving the water plant approximately 5,000 feet to facilitate water deliveries to locations further from the water treatment facility.

There is potential to reduce dependency on groundwater during summer months when the City of Lodi is still pumping as much as 10 MGD from the ground to support the water plant. Groundwater savings could be as high as 6,000 AF/year; however, 4,500 to 5,000 AF/year of savings is expected. The delivery of additional raw surface water will need to be secured for this project to proceed.

Project Summary
Submitting GSA: City of Lodi
Project Type: In-lieu Recharge
Estimated Groundwater Offset and/or Recharge: 4,750 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: This project is in the planning/initial study phase. The required plumbing and infrastructure exist; however, pumps and corresponding equipment would need to be purchased. The City has not completed a study or performed engineering modelling related to feasibility. Increasing capacity would allow for more surface water diversion during summer months, but it is unlikely that during the winter months demand would exceed the current plant capacity.

The City anticipates meeting peak summer demand with more surface water, which currently exceeds the 4,000 AF that is supplied by wells.

Required Permitting and Regulatory Process: This project requires SWRCB permitting and re-classification for plant upsizing. CEQA review will also need to be completed.

Time-table for Initiation and Completion: The timeline for this project has not yet been developed, but it is estimated that this project could begin in 2030 and be completed by 2033. Benefits would be realized beginning the first summer following the plant expansion and remain in perpetuity.

Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply (surface water) will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. This project is anticipated to offset 4,750 AF/year in groundwater pumping in the City of Lodi through the expansion of treated surface water. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The City of Lodi relies on Woodbridge Irrigation District (WID) for surface water deliveries and does not currently have a contract allowing for higher volumes to be supplied.

This project relies entirely on the availability of additional surface water deliveries from WID (Mokelumne River water), which will need to be negotiated at the onset of this project.

Legal Authority: The City of Lodi has legal authority to administer this project through California Water Code (CWC) §71000-73000. Additional legal and contract negotiations will be needed with WID for additional surface water deliveries.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-31
Projects and Management Actions November 2024
Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $4 million in capital costs, $240,000 in fixed annual operations and maintenance costs, and $2.1 million in annual variable costs (amount is variable depending on water purchase, power, and chemical needs). This project is a Capital Improvement Project Budgeted item, to be paid for from the water enterprise fund.

Circumstances for Implementation: This project is a Planned Project that is anticipated to move forward. As scenarios change, the Potential Projects can come online to bring additional resources for adaptive management. Implementation of Potential Projects will be based on long-term management or changing needs of the GSA or Subbasin.

Trigger for Implementation and Termination: Expansion of the Surface Water Treatment Facility (SWTF) will be initiated when the City of Lodi is unable to meet its growing water demand with the current infrastructure. There is no expectation that this project would be terminated based on a decision made by the City of Lodi. The potential for reduced availability of surface water supply from WID would be the only potential cause for a reduction in SWFT production.

Process for Determining Conditions Requiring the Project have Occurred: In reviewing current water demands, as well as future projections of use, City of Lodi staff will determine whether an expansion of the SWTF is appropriate or not and make a recommendation to City Council. This is currently a planned project that is anticipated to move forward and be online by 2040.

6.2.5.3 BNSF Railway Company Intermodal Facility Recharge Pond Under this proposed project, CSJWCD would form an agreement with the BNSF railroad owner to access an existing drainage pond near the CSJWCD delivery channel to be used as a recharge area. This project would contribute an estimated 1,000 AF/year of groundwater offset through direct recharge to the groundwater aquifer.

Project Summary
Submitting GSA: Central San Joaquin Water
Conservation District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: 1,000 AF/year Other Participating Entities: BNSF Railway
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: This project is in the planning stages.

Required Permitting and Regulatory Process: A streambed alteration permit would be required to construct a diversion structure from the District delivery channel to feed the recharge pond.

Time-table for Initiation and Completion: This project is anticipated to proceed in WY 2024, subject to available funding.

Expected Benefits and Evaluation: This project is anticipated to directly recharge 1,000 AF/year to the groundwater basin in CSJWCD. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project will rely on water from the New Melones Unit Central Valley Project. The surface water source is based upon a contract for delivery of surface water from the New Melones Unit of the Central Valley Project. The contract project is long-term; however, water availability is subject to drought conditions. This is an existing water right.

Legal Authority: The Water Code, Division 21, §74000 et seq. authorizes CSJWCD to acquire, sell, and distribute water and fix rates for service throughout the District.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-32
Projects and Management Actions November 2024
Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $150,000 in capital costs and $50,000 in annual operations and maintenance costs. Costs for this project would be met by groundwater extraction fee revenue, private loans, and/or possible grant funding.

Circumstances for Implementation: This project is currently in the planning stages and may move forward if funding becomes available. Category B projects represent a “menu of options” for the Subbasin to achieve long-term sustainability and offset the remaining imbalance above and beyond implementation of the Category A projects. As scenarios change, this project can come online to bring additional resources for adaptive management. In this case, the project parties plan to implement this project as soon as a finalized agreement with the landowner is reached and permitting and funding are established.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of Category B projects will be based on long-term management or changing needs of the GSA or Subbasin.

6.2.5.4 Manaserro Recharge Project
NSJWCD is investigating constructing and operating a 10-acre recharge pond on the north side of the Mokelumne River on property owned by the Manaserro family through a long-term lease. NSJWCD would use Permit 10477 water, available during December 1 through June 30 that is not needed for irrigation, for recharge. This project could recharge 8,000 AF/year or more in years when water is available. Because this project can use water available during the direct diversion flood season, water is expected to be available more frequently under the NSJWCD water right for this project, or 80 percent of years. Capital costs assume that NSJWCD would lease the 10-acre property for this project.

Project Summary
Submitting GSA: North San Joaquin Water
Conservation District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: 8,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: This project is in the planning phase. NSJWCD is continuing to work on a strategic plan and funding options for the implementation of this project, and continuing negotiations with the landowner.

Required Permitting and Regulatory Process: This project would require CEQA review, a possible grading permit, and a possible water right change petition.

Time-table for Initiation and Completion: This project is anticipated to completed by 2025.

Expected Benefits and Evaluation: This project is anticipated to directly recharge 8,000 AF/year to the groundwater basin in NSJWCD. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project would use water supplies available through NSJWCD Permit 10477 (Mokelumne River water). This is an existing surface water right. Once Permit 10477 supplies are fully committed to in-lieu recharge projects, NSJWCD could apply to appropriate Mokelumne River flood flows for this direct recharge project.

Legal Authority: The legal authority for this project is covered under Water Code §74000 et seq.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-33
Projects and Management Actions November 2024
Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $300,000 in capital costs and $400,000 in annual operations and maintenance costs. Costs for this project will be met by grant funding and landowner assessments (pending approval).

Circumstances for Implementation: This project is a Category B project and may move forward as funding becomes available. Category B projects represent a “menu of options” for the Subbasin to achieve long-term sustainability and offset the remaining imbalance above and beyond implementation of the Category A projects. As scenarios change, the project can come online to bring additional resources for adaptive management. Circumstances for implementation include securing funding. Project may be implemented on a smaller scale depending on use of water by other projects in the District.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this will depend on funding availability, securement of the property lease and planning.

6.2.5.5 City of Escalon Wastewater Reuse
This project entails the reuse of wastewater that would include tertiary treatment of the City of Escalon’s effluent and blending in SSJID’s irrigation distribution system. This additional source of supply could then be used for groundwater recharge or transfer within the Subbasin to offset groundwater demands using SSJID facilities and/or water right entitlements to facilitate the transfer. The treated water will meet Title 22 Water Standards.

The City of Escalon’s Wastewater Treatment Plant treats approximately 600,000 gallons per day (1.84 AF per day) with peak flows up to 1 MGD. The plant is located near SSJID’s Main Distribution Canal, and the effluent would need to be pumped and a pipeline of approximately 4,000 linear feet would need installed in addition to improvements at the plant to meet Title 22 Water Standards.

Project Summary
Submitting GSA: South San Joaquin GSA
Project Type: Recycling/Direct Recharge/
Intrabasin Transfer
Estimated Groundwater Offset and/or Recharge: 672 AF/year Other Participating Entities: City of Escalon
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing water recycling and direct recharge opportunities.

Project Status: This project is in the planning phase.

Required Permitting and Regulatory Process: This project would require CEQA review, Regional Water Quality Control Board permitting, and road encroachment permits.

Time-table for Initiation and Completion: This project would begin in 2030 and would be completed by 2035.

Expected Benefits and Evaluation: This project is anticipated to offset 672 AF/year in groundwater pumping for use in direct recharge in the City of Escalon or in inter-basin transfers to other areas of the Subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations How Project Will Be Accomplished/Evaluation of Water Source: This project will rely on the use of recycled water, in the form of tertiary-treated Title-22 effluent form the City of Escalon’s Wastewater Treatment Plant. No additional water source will be utilized for this project.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-34
Projects and Management Actions November 2024
Legal Authority: The City of Escalon is an incorporated city and provides municipal services including wastewater treatment. SSJID is an irrigation district formed in accordance with State law.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $18 million in capital costs and $400,000 in annual operations and maintenance costs. Costs for this project will be met by developer impact fees, connection fees, and sewer rate fees.

Circumstances for Implementation: This project is a Category B project, meaning it is currently in the planning stages and may move forward if funding becomes available. Category B projects represent a “menu of options” for the Subbasin to achieve long-term sustainability and offset the remaining imbalance above and beyond implementation of the Category A projects.. Provided this project is feasible, as determined in the initial planning phase, the Escalon City Council would need to approve this project as well as the SSJID Board of Directors.

Trigger for Implementation and Termination: This project would need to be determined to be feasible with adequate funding likely from multiple sources such as development impact fees, connection fees, and sewer rate fees.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project be based on the results of a feasibility analysis. The Escalon City Council would need to make the requisite findings and approve a financing package for this project.

6.2.5.6 City of Ripon Surface Water Supply
The City of Ripon serves water to 15,000 residents along with businesses and industries located within its limits. This project would supplement the City of Ripon’s municipal water supply with treated surface water from SSJID. A 5-mile pipeline from the existing treated water transmission pipeline to Ripon’s water distribution system and a booster pump station would need to be constructed.

The City of Ripon is currently under contract with SSJID for a maximum of 6,000 AF/year of Stanislaus River water, which is the expected water supply for this project.

Project Summary
Submitting GSA: South San Joaquin GSA
Project Type: In-lieu Recharge
Estimated Groundwater Offset and/or Recharge: 6,000 AF/year Other Participating Entities: City of Ripon
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: The design for this project is complete. The City is pursuing a National Environmental Policy Act (NEPA) Categorical Exclusion and CEQA Mitigated Negative Declaration. Construction of this project will begin once this project is fully funded. Construction is expected to take one year.

Required Permitting and Regulatory Process: This project will require a NEPA Categorical Exclusion and CEQA Mitigated Negative Declaration. Road encroachment permits will also be required.

Time-table for Initiation and Completion: This project would begin in 2028 and would be completed by 2030.

Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and will be critical to establishing long-term Subbasin sustainability. This project is anticipated to offset 6,000 AF/year in groundwater pumping in the City of Ripon. Benefits are expected to accrue for 50 years, through 2074. Benefits to groundwater levels will be evaluated through ESJWRM model simulations. This proposed conjunctive use project would provide the community of Ripon, along with the region that relies on the groundwater Subbasin, with numerous benefits, including:

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-35
Projects and Management Actions November 2024
• Conservation of groundwater through in-lieu recharge
• Use of renewable energy and energy conservation
• Safer and cleaner drinking water
How Project Will Be Accomplished/Evaluation of Water Source: SSJID holds pre-1914 water rights on the Stanislaus River. This is an existing surface water right. The City of Ripon has an agreement in place to divert a maximum of 6,000 AF/year from SSJID facilitates under SSJID’s existing pre-1914 water right, which is the expected water supply for this project.

Legal Authority: The City of Ripon is an incorporated city and provides municipal water service. SSJID is an irrigation district formed in accordance with State law. SSJID holds pre-1914 water rights on the Stanislaus River.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $8.6 million in capital costs.

Costs for this project will be met by grants, water rates, and development impact fees.

Circumstances for Implementation: This project is a Category B project, meaning it is currently in the planning stages and may move forward if funding becomes available. Category B projects represent a “menu of options” for the Subbasin to achieve long-term sustainability and offset the remaining imbalance above and beyond implementation of the Category A projects.. The City of Ripon is in the process of completing the environmental documentation for this project and securing the necessary finances to move forward.

Trigger for Implementation and Termination: Project implementation will initiate once this project is approved by the City of Ripon and the financing is in place. Termination would be subject to the terms of the agreement if applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of Potential Projects will be based on long-term management or changing needs of the GSA or Subbasin. The Ripon City Council would need to make the requisite findings under NEPA, CEQA, and approve a financing package for project construction.

6.2.5.7 City of Escalon Connection to Nick DeGroot Water Treatment Plant The City of Escalon partnered in the construction of the Nick DeGroot Water Treatment Plant and continues to provide financial partnership in its operation. However, Escalon has not constructed the turnout and distribution system improvements necessary to receive their surface water allotments. Finance and construction of these improvements would make it possible for Escalon to receive their contract entitlements under Phase 1 (2,015 AF) further reducing Escalon’s groundwater demand. Escalon, as a partner city in the plant, could readily begin receiving water once turnout improvements and distribution pipelines are constructed. SSJID operates the Nick DeGroot Water Treatment Plant and serves treated Stanislaus River water under its pre-1914 water right to the cities of Manteca, Lathrop, and Tracy.

Project Summary
Submitting GSA: South San Joaquin GSA
Project Type: In-lieu Recharge
Estimated Groundwater Offset and/or Recharge: 2,015 AF/year Other Participating Entities: City of Escalon and SSJID Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: This project is in the conceptual design phase. Environmental review has been completed. The project is pending further design work and rate study by the Council.

Required Permitting and Regulatory Process: This project will require road encroachment permits.

Time-table for Initiation and Completion: This project would begin in 2028 (pending funding) and be completed by 2030.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-36
Projects and Management Actions November 2024
Expected Benefits and Evaluation: Groundwater Subbasin recharge through the in-lieu use of alternate water supply will be an important component of the GSP and critical to establishing long-term Subbasin sustainability. This project anticipated to offset 2,015 AF/year in groundwater pumping in the City of Escalon. Benefits are expected to accrue for 50 years, through 2073. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: SSJID holds pre-1914 water rights on the Stanislaus River. This is an existing surface water right.

Legal Authority: The City of Escalon is an incorporated city and provides municipal water service. SSJID is an irrigation district formed in accordance with State law. SSJID holds pre-1914 water rights on the Stanislaus River. The City of Escalon is project partner in the Nick DeGroot Water Treatment Plant and has an existing agreement with SSJID which entitles Escalon to receive 2,015 AF/year of treated surface water.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $8,789,000 in capital costs and $250,000 in annual operations and maintenance costs. Costs for this project will be met by grants, water rates, and development impact fees.

Circumstances for Implementation: This project is a Category B project, meaning it is currently in the planning stages and may move forward if funding becomes available. Category B projects represent a “menu of options” for the Subbasin to achieve long-term sustainability and offset the remaining imbalance above and beyond implementation of the Category A projects. The environmental review for this project has been completed and the City of Escalon is in the process of securing the necessary finances to move forward.

Trigger for Implementation and Termination: Project implementation will initiate once this project is approved by the City of Escalon and the financing is in place. Termination would be subject to the terms of the agreement if applicable Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project will be based on the Escalon City Council making the requisite findings and approving a financing package and rate increase for this project.

6.2.5.8 Farmington Dam Repurpose Project
This proposed project would convert the Farmington Dam, currently a flood control structure, into a water supply reservoir. This existing Farmington Dam has a flood control capacity of 52,000 AF. The proposed project would increase the total reservoir capacity to 112,000 AF which includes 60,000 AF for water supply and 52,000 AF for flood control. The water supply could be stored and used even in drought conditions. The increased water supply would also encourage growers to switch to surface water irrigation instead of reliance on groundwater.

USACE completed a reconnaissance report in 1997 with an estimated cost of $91.4 million based on an effective pricing date of October 1996. Including environmental and cultural resources mitigation costs, which were not included in 1997, the cost today would be approximately $175 million.

Other entities that would benefit from this project includes CSJWCD and potentially OID.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: 15,500 - 60,000 AF/year Other Participating Entities: USACE
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-37
Projects and Management Actions November 2024
Project Status: This project is in the pre-planning stage. A reconnaissance study has been completed. SEWD has been working with Congressmen Harder to include this project in the 2024 Water Resources Development Act bill to reauthorize a new feasibility study.

Required Permitting and Regulatory Process: The required permitting for this project would include acquiring permits/approvals from SWRCB, USBR, California DFW, RWQCB, CVFPB, and USACE.

Time-table for Initiation and Completion: This project would begin in 2030 and be completed by 2050.

Expected Benefits and Evaluation: This project is anticipated to directly recharge 60,000 AF/year to the groundwater basin in SEWD. Benefits to groundwater levels will be evaluated through model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: SEWD and CSJWCD have a water supply contract with USBR to use water from the New Melones Reservoir (Stanislaus River water). This is an existing surface water right.

Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping. Farmington Dam is owned and operated by USACE, and upon agreement, and USACE would be the agency with authority to modify the dam structure.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $175 million in capital costs and $2 million in annual operations and maintenance costs. Costs for this project will be met through the pursual of grant funding.

Circumstances for Implementation: This project is a Category B project in the early planning stages and will require significant additional work to move forward. This project could be implemented when agreements are reached with all applicable federal and state regulatory agencies and when funding is available.

Trigger for Implementation and Termination: The trigger for implementation and termination would be the water supply from New Melones Reservoir and groundwater levels in the Subbasin.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project will depend on the successfully execution of agreements with applicable federal and state agencies, and after securing funding to complete design, environmental documentation and construction.

6.2.5.9 Mobilizing Recharge Opportunities
This project would put in place a framework to quickly mobilize and take advantage of recharge opportunities (e.g., existing storm ponds, lake features, temporary flood easements, agricultural field ponding, etc.) This project would provide access to funding to expedite recharge projects as opportunities arise. Additional governance and budgetary controls would need to be developed. Flood-Managed Aquifer Recharge (Flood-MAR) opportunities will be considered through ongoing coordination with existing agencies.1
Project Summary
Submitting GSA: San Joaquin County
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: 110,000 – 158,000 AF/year 1 Flood-MAR is an integrated and voluntary resource management strategy that uses flood water resulting from, or in anticipation of, rainfall or snow melt for managed aquifer recharge (MAR) on agricultural lands and working landscapes, including but not limited to refuges, floodplains, and flood bypasses. Flood-MAR can be implemented at multiple scales, from individual landowners diverting flood water with existing infrastructure, to using extensive detention/recharge areas and modernizing flood management infrastructure/operations (CA DWR, 2019).

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-38
Projects and Management Actions November 2024
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct and/or in-lieu recharge opportunities.

Project Status: This project is still in the early development stages. Under a SGMA Implementation Grant Program Round 1 award, the County has begun advancing the project to put to beneficial use water appropriated through the Mokelumne River Water and Power Authority’s water right application using existing and new infrastructure.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: The initiation of this project may begin in 2024, with environmental review and water rights applications beginning in 2025, and expected project completion by 2040.

Expected Benefits and Evaluation: This project is anticipated to directly recharge the groundwater basin in areas that are geographically dispersed throughout the Subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

Legal Authority: [Information pending]
Estimated Costs and Plans to Meet Costs: A portion of this project has been funded through a SGMA Round 1 Implementation Grant. The remaining costs for this project and approach for meeting costs are unknown at this time.

Circumstances for Implementation: The plan to be developed under this project has just begun. Once completed, potentially feasible projects would have to undergo design, environmental review, permitting and construction prior to any operation.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of feasible projects identified in the study being conducted under the grant funding would need to be approved by the identified implementation agency(ies). Design, environmental review, permitting and construction, and the funding stream to support those efforts, would have to occur before the feasible projects can be brought online.

6.2.5.10 NSJWCD Winery Recycled Water
This project will blend NSJWCD Permit 10477 water with wastewater from winery(ies) and deliver blended water for irrigation to accomplish in-lieu recharge or put in recharge ponds and accomplish direct groundwater recharge.

Project Summary
Submitting GSA: North San Joaquin Water
Conservation District
Project Type: Recycling/In-lieu Recharge/
Direct Recharge
Estimated Groundwater Offset and/or Recharge: 750 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing recycling, in-lieu recharge, and direct recharge opportunities.

Project Status: This project is in the early stages of discussing concepts with a local winery.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-39
Projects and Management Actions November 2024
Required Permitting and Regulatory Process: This project would require WDR permitting through the Central Valley Regional Water Quality Control Board (CVRWQCB). Minor permits would be required for pipeline construction.

Time-table for Initiation and Completion: This project would begin in 2025 and be completed by 2027.

Expected Benefits and Evaluation: This project is anticipated to offset 750 AF/year in groundwater pumping in NSJWCD for use in in-lieu or direct recharge.

How Project Will Be Accomplished/Evaluation of Water Source: This project will blend NSJWCD Permit 10477 (Mokelumne River water) with wastewater from wineries.

Legal Authority: The legal authority for this project is covered under Water Code §74000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $1.5 million in capital costs and $100,000 in annual operations and maintenance costs. Costs for this project will be met by grant funding, landowner assessments (pending approval), and charges paid by the winery (pending contract).

Circumstances for Implementation: This project is a conceptual project currently in the early stages and would require significant additional work to move forward. Funding would have to be secured to advance project design, permitting, environmental review and construction, and coordination contracts with the participating winery(ies) executed before the projects can be brought online.

Trigger for Implementation and Termination: Not applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this will be based on longterm management or changing needs of the GSA or Subbasin, the willingness of local winery(ies) to participate, and the availability of funding.

6.2.5.11 SSJID Storm Water Reuse
SSJID and the cities of Ripon and Escalon have previously proposed storm water capture for storage and irrigation reuse, or for groundwater recharge to benefit the groundwater Subbasin. Currently, the City of Escalon, and to a limited extent the City of Ripon, discharge storm water into SSJID facilities during the winter months. This storm water is conveyed through SSJID’s main canal or lateral irrigation distribution system and eventually is conveyed into the Stanislaus River or the San Joaquin River via French Camp Slough. Capturing and storing excess storm water would allow for quantities of water that could be used to offset or enhance groundwater in multiple ways. SSJID is in the process of quantifying the amount of storm water it discharges during the winter months that could be made available to be repurposed for sustainable groundwater management practices. Additional infrastructure may be needed to provide adequate storage for groundwater recharge.

The City of Escalon currently has a drainage area of approximately 1,200 acres with 10 drainage systems which accumulate to a maximum discharge capacity of approximately 50 cubic feet per second (cfs) that drains into two District Laterals. It is estimated on average that 700 AF/year of run-off comes from the City of Escalon. The City of Ripon currently has a drainage area of approximately 2,200 acres with four drainage systems. The majority of the storm run-off discharges to the Stanislaus River. A portion of storm water discharges into the District’s laterals and canals. It is estimated approximately 400 AF/year of run-off discharges to District facilities. Additional monitoring will need to be implemented to obtain more accurate discharge flows from both cities.

Preliminary cost estimate includes two 20-acre storm drain retention basins in each city strategically located near District facilities.

Project Summary
Submitting GSA: South San Joaquin GSA
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-40
Projects and Management Actions November 2024
Project Type: Storm Water/In-lieu Recharge/
Direct Recharge
Estimated Groundwater Offset and/or Recharge: 1,100 AF/year Other Participating Entities: City of Escalon, City of Ripon, SSJID
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing storm water capture, in-lieu recharge, and direct recharge opportunities.

Project Status: This project is in the planning/initial study phase.

Required Permitting and Regulatory Process: This project will require CEQA review and road encroachment permits.

Time-table for Initiation and Completion: This project would begin in 2027 and be completed by 2030.

Expected Benefits and Evaluation: This project is anticipated to offset 1,100 AF/year in groundwater pumping in SSJ GSA for use in in-lieu or direct recharge. Benefits are expected to accrue for 50 years, through 2080. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project would rely on the use of captured storm water. No additional water source will be utilized for this project.

Legal Authority: The Cities of Escalon and Ripon are incorporated cities and provide municipal stormwater/drainage services. SSJID is an irrigation district formed in accordance with State law and also provides limited drainage service.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $30 million in capital costs and $30,000 in annual operations and maintenance costs. Costs for this project will be met by developer impact fees, connection fees, and sewer rate fees.

Circumstances for Implementation: This project is in the early conceptual planning stages and would require significant additional work to move forward. The project proponents are in the process of determining the feasibility of this project, including the possibility of securing the necessary finances to move forward.

Trigger for Implementation and Termination: Project implementation would begin once this project is approved by the cities of Escalon and Ripon, and the SSJID Board of Directors, and a financing plan is in place. Termination would be subject to the terms of the agreement if applicable.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project will be based on long-term management or changing needs of the GSAs or Subbasin, and the availability of funding to further the project.

6.2.5.12Wallace-Burson Conjunctive Use Program
This project would use surface water from New Hogan Reservoir, Mokelumne State-Filed Rights Application, and/or purchased water for direct recharge into the groundwater basin and/or to offset groundwater pumping. Surface water would be recharged in the Wallace Service Area and the communities of Burson and Southworth.

Project Summary
Submitting GSA: Eastside GSA
Project Type: Conjunctive Use/ Direct
Recharge
Estimated Groundwater Offset and/or Recharge: 500 - 3,000 AF/year EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-41
Projects and Management Actions November 2024
Measurable Objective Expected to Benefit: This project addresses the chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities and/or conjunctive use.

Project Status: This project is still in the conceptual planning and discussion stages. Hydrogeology and water supply studies have been developed, and the design of specific program facilities is ongoing.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: The initiation of this project may begin by 2030 with completion by 2040, if funding is identified and the project is implemented.

Expected Benefits and Evaluation: This project is anticipated to directly recharge the groundwater basin in areas that are geographically dispersed throughout the Subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

Legal Authority: The legal authority for this project is covered under Water Code § 30000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project and approach for meeting costs are unknown at this time.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this project will be based on long-term management or changing needs of the GSA or Subbasin, the availability of funding, and the willingness of project partners to design, construct and execute the project.

6.2.5.13Calaveras River Wholesale Water Service Expansion Calaveras County Water District (CCWD) has available surface water supply to set up agreements that would facilitate in-lieu recharge opportunities in the Calaveras County portion of the Subbasin. This project would identify opportunities for the conjunctive use and recharge of surface water into the groundwater basin. The amount of recharge will be dependent on the opportunities identified, and projects developed and implemented.

Project Summary
Submitting GSA: Eastside GSA
Project Type: In-Lieu Recharge
Estimated Groundwater Offset and/or Recharge: 200 - 600 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: This project is still in the conceptual development stages.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-42
Projects and Management Actions November 2024
Time-table for Initiation and Completion: The initiation and completion dates for this project are currently unknown.

Expected Benefits and Evaluation: This project is anticipated to recharge the groundwater basin in the Calaveras County portions of the Subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

Legal Authority: The legal authority for this project is covered under Water Code § 30000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project and approach for meeting costs are unknown at this time.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: This project is in the early stages of planning.

Implementation of the project will be based on long-term management or changing needs of the GSA or Subbasin.

6.2.5.14Recycled Water to Manteca Golf Course
In response to growing demands for recycled water projects, the City of Manteca adopted the Reclaimed Water Facilities Master Plan in January 2023. The City is pursuing recycled water projects to create a replenishable water source for irrigation and water storage. This project would send reclaimed water to irrigate the Manteca Golf Course.

Once the recycled water infrastructure is in place, an estimated 5,000 AF/year of groundwater could be offset by the use of recycled water for irrigation.

Project Summary
Submitting GSA: City of Manteca
Project Type: Recycling
Estimated Groundwater Offset and/or Recharge: 406 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by providing recycled water for irrigation, rather than being supplied by groundwater.

Project Status: A 12-inch pipeline that would deliver reclaimed water has been installed. The City is currently pursuing other funding, such as grants, to finance the construction of pump stations and storage tanks needed to deliver the recycled water.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: The completion dates for this project are currently unknown.

Expected Benefits and Evaluation: This project is anticipated to offset groundwater pumping with the use of recycled water. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

Legal Authority: This project is under the authority of the City of Manteca and implemented within the City’s service area.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-43
Projects and Management Actions November 2024
Estimated Costs and Plans to Meet Costs: The estimated costs for this project and approach for meeting costs are unknown at this time.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: Funding is required to complete the design, environmental review, permitting and construction of project facilities. As such, implementation of this project will be based on long-term management or changing needs of the GSA or Subbasin and the fiscal feasibility of the project.

6.2.5.15Threfall Ranch Reservoir, In-Lieu and Direct Recharge Project This project involves the construction of an unlined reservoir which could provide an estimated 2,000 AF/year of in-lieu recharge in the Subbasin. The reservoir is designed to be unlined, allowing an unspecified volume of water to seep into the groundwater basin through direct recharge.

Project Summary
Submitting GSA: Eastside GSA
Project Type: In-Lieu Recharge/ Direct
Recharge
Estimated Groundwater Offset and/or Recharge: 2,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu and/or direct recharge opportunities.

Project Status: The final design of this project has been completed. Once funding has been identified, environmental review and permitting for the project will begin.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: This project is anticipated to be completed by 2025.

Expected Benefits and Evaluation: This project is anticipated to provide water for in-lieu and direct recharge in the critically overdrafted subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

Legal Authority: The legal authority for this project is covered under Water Code § 30000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project and approach for meeting costs are unknown at this time.

Circumstances for Implementation: The need for funding is the key factor in the implementation of this project. Funding is required to prepare the environmental review documentation, complete permitting, and for project construction and startup.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-44
Projects and Management Actions November 2024
Process for Determining Conditions Requiring the Project have Occurred: Implementation this project will be based on long-term management or changing needs of the GSA or Subbasin and the identification of funding required to complete environmental review documentation, permitting, and for project construction and startup.

6.2.5.16Perfecting Mokelumne River Water Right (MICUP Project) This project advances MRWPA’s Water Right Application 29835 (A029835) to a Water Right Permit with the State Water Resources Control Board. The application aims to appropriate up 110,000 acre-feet of unappropriated wet year flows from the Mokelumne River annually, with an additional 48,000 acre-feet/year of storage. Appropriated water could be used for addressing groundwater overdraft concerns in the Subbasin by storing wet-year water for use during drier periods.

Project Summary
Submitting GSA: San Joaquin County
Project Type: In-Lieu Recharge
Estimated Groundwater Offset and/or Recharge: 110,000 - 158,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu recharge opportunities.

Project Status: The water rights application for this project is in progress. A Notice of Preparation for CEQA documentation was issued in July 2024.

Required Permitting and Regulatory Process: SWRCB water rights permitting, plus other project-specific permitting as required to put the water to beneficial use.

Time-table for Initiation and Completion: Implementation of this project has begun, with an expected completion by 2025.

Expected Benefits and Evaluation: This project is anticipated to amend the water right application to provide future inlieu recharge opportunities in the groundwater basin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project is contingent on the SWRCB Division of Water Rights approval of the water right application for the diversion of surface water from the Mokelumne River.

Legal Authority: The legal authority for this project is that accorded under the California Government Code to joint powers of authority for the provision of public services.

Estimated Costs and Plans to Meet Costs: $125,000 has been spent to date. The estimated remaining costs for this project and approach for meeting costs are unknown at this time.

Circumstances for Implementation: SWRCB Division of Water Rights approval of the water rights application and issuance of a water right permit is required for successful implementation of this project.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this will be based on securing a water right to the MRWPA’s Water Right Application 29835 (A029835) and to identifying, developing and constructing the projects to put that water right to beneficial use to address the long-term management or changing needs of the GSA or Subbasin.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-45
Projects and Management Actions November 2024

6.2.5.17 North System Groundwater Recharge Project - Phase 2 The North System Master Plan will identify opportunities for direct and/or in-lieu recharge of the underlying critically overdrafted subbasin. Preliminary estimates indicate that additional 1,000-3,000 AF/year of recharge could occur off the North System in wet and normal years through either direct and/or in-lieu recharge.

Project Summary
Submitting GSA: North San Joaquin Water
Conservation District
Project Type: In-Lieu/ Direct Recharge
Estimated Groundwater Offset and/or Recharge: 1,000 - 3,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu and direct recharge opportunities.

Project Status: The Master Plan for the entire North System is currently in progress. A team has also been retained to design and build a new pump station in 2024-2026.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: Construction on this project is anticipated to begin in 2026 with completion by 2029.

Expected Benefits and Evaluation: This project is anticipated to directly recharge the groundwater basin in the North System extent of NSJWCD. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

Legal Authority: The legal authority for this project is covered under Water Code §74000 et seq.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $10 million in capital costs and $100,000 in annual operations and maintenance costs. A $3 million state grant was secured to help with project costs.

Additional funds for this project will be met by landowner assessments, water charges, and any further grant funds the District can obtain.

Circumstances for Implementation: Completion of the North System Master Plan will identify potential projects for direct and/or in-lieu recharge. The circumstances for implementation of projects identified in the Master Plan are unknown at this time and will be project dependent.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: The Master Plan for the North System will identify opportunities for direct and in-lieu recharge in the North System of the District’s service area. Design, permitting, and environmental review will need to be completed on the most feasible projects before construction can begin.

6.2.5.18 Stormwater Collection, Treatment, and Infiltration The City of Manteca will conduct a study to determine what space may be available for use in a stormwater recharge program, identify treatment technologies available and determine volume of rainwater available for groundwater recharge. The City is currently working on identifying a funding source for the study.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-46
Projects and Management Actions November 2024
Project Summary
Submitting GSA: City of Manteca
Project Type: Direct Recharge/ Stormwater
Estimated Groundwater Offset and/or Recharge: To be determined Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by identifying potential direct recharge opportunities using captured stormwater.

Project Status: This project is still in the early planning and initial study stage.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: The initiation and completion dates for this project are currently unknown.

Expected Benefits and Evaluation: This project is anticipated to identify opportunities for direct recharge into the groundwater basin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

Legal Authority: This project is under the authority of the City of Manteca and implemented within the City’s service area.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project and approach for meeting costs are unknown at this time.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of longer-term projects will be based on long-term management or changing needs of the GSA or Subbasin and availability of funding.

6.2.5.19 Off-Stream Regulating Reservoir
This project would provide additional opportunities for the direct recharge of surface water into the underlying groundwater basin. This project would use surface water from the New Hogan Reservoir (Calaveras River water) using existing and pending surface water rights.

This project is currently in the early design stages. SEWD has identified a preliminary list of ideal locations based on the operational benefits to the distribution system. These locations will be compared against areas most suitable for recharge. Discussions with landowners are necessary, and land acquisition may also be required. The amount of recharge that this project may provide is still unknown at this time.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: To be determined Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by providing additional direct recharge opportunities.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-47
Projects and Management Actions November 2024
Project Status: This project is still in the early conceptual stages.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: The initiation and completion dates for this project are currently unknown.

Expected Benefits and Evaluation: This project is anticipated to directly recharge the groundwater basin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project relies on water from New Hogan Reservoir (Calaveras River water under existing and possible future surface water rights.

Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping Estimated Costs and Plans to Meet Costs: The estimated costs for this project are unknown at this time. The project would hopefully be funded through grant funds.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this longer-term project will be based on long-term management or changing needs of the GSA or Subbasin.

6.2.5.20 On-Farm Recharge Project
The District has developed and approved an On-Farm Recharge Policy to incentivize farmers to participate in FloodMAR opportunities. The project would use existing farm infrastructure to divert surface water for direct recharge through FloodMAR, or potentially dry wells. SEWD is currently looking for agricultural customers to participate in this program.

As such, the amount of water that may be recharged through this program is unknown at this time.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: To be determined Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: This project is still in the early project planning stages.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: The initiation and completion dates for this project are currently unknown.

Expected Benefits and Evaluation: This project is anticipated to directly recharge water into the groundwater basin.

Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-48
Projects and Management Actions November 2024
Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $100,000 in annual operations and maintenance costs. Costs for this project will be met by district staffing, district rates created to establish a new Flood-MAR project, and other district funding for on-farm incentive programs.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this longer-term project will be based on long-term management or changing needs of the GSA or Subbasin.

6.2.5.21 Bellota Weir Modifications Project
The purpose of the Bellota Weir Modifications Project is to provide fish passage for the Central Valley Steelhead in addition to providing more efficient water diversion and flow metering of agricultural, municipal and ecological water.

The project will conserve approximately 1,100 AF annually of surface water upon completion of Phase 1 with the installation of the concrete sill. The project will increase the Old Calaveras River recharge from 6,300 acre-feet (AF) to 11,500 AF annually per the SEWD’s water rights on the Calaveras River.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: Direct Recharge/ Stormwater
Estimated Groundwater Offset and/or Recharge: 2,000 - 5,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: This project is still in the design stages. SEWD has promoted the project in Washington DC in order to secure funding through appropriations.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: This District is looking to secure funding for the project. The anticipated completion of this project is by 2030.

Expected Benefits and Evaluation: The project will allow for the controlled flow into the Old Calaveras River to increase infiltration of surface water into the underlying critically overdrafted Subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $85 million in capital costs.

Costs for annual operations and maintenance are still unknown. SEWD is looking to obtain grant funding and state and federal loans to cover the costs of this project.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-49
Projects and Management Actions November 2024
Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this longer-term project will be based on the availability of funding and the long-term management or changing needs of the GSA or Subbasin.

6.2.5.22 Water Supply Enhancement Project - Distribution Pipelines This project aims to enhance water supply accessibility for on-farm in-lieu recharge by distributing surface water to the Linden area through a network of proposed pipelines, including the Clements Gravity pipeline, Houston Gravity pipeline, Demartini pipeline, and Mosher pipeline. By providing surface water to farmers who currently lack access, the project will significantly reduce groundwater overdraft in these regions. The estimated water offset ranges from 5,000 to 17,000 acre-feet per year, depending on the water year type. SEWD is coordinating with landowners in the project area to secure easements and gauge interest in participation.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: In-Lieu/ Direct Recharge
Estimated Groundwater Offset and/or Recharge: 17,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing in-lieu and direct recharge opportunities.

Project Status: This project is still in the early design stages.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: The initiation dates for this project are currently unknown.

Expected Benefits and Evaluation: This project is anticipated to provide access to surface water to those who currently don’t have access, thereby greatly reducing groundwater overdraft. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as project develops.

Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project and approach for meeting costs are unknown at this time.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: The project is currently in the preliminary design phase. The environmental review and permitting of the project remain to be completed ahead of construction.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-50
Projects and Management Actions November 2024

6.2.5.23 Water Treatment Plant Aquifer Storage Recovery Well – 7401 This project will recharge treated water directly into the groundwater basin and store it until periods of drought, when the water can be extracted and used. A new aquifer storage and recovery (ASR) well will be installed near SEWD’s water treatment plant, capable of recharging up to 350 gpm and producing 1,500 gpm. The well will serve as a supplemental water source for the water treatment plant in dry years and will be used to directly recharge groundwater in wet years. The estimated range of water available for recharge is between 1,000 and 2,420 acre-feet per year, depending on the water year type and availability.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: 1,000 - 2,420 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: This project is currently being implemented. Design has been completed, and funding has been secured. Construction is scheduled to begin in 2025, with anticipated completion by 2026.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: This project has been initiated and expected to be completed by 2026.

Expected Benefits and Evaluation: This project is anticipated store excess water in wet years for later use in drought periods, thereby reducing the groundwater deficit. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: Supply to this well for aquifer storage will be treated water from the Cal Water distribution system.

Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $1.5 million in capital costs.

Funding sources for this project have not yet been identified.

Circumstances for Implementation: Environmental documentation and permitting remain to be completed before the project can be bid and constructed.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: This project is a Category B project on which design has been completed. Additional work, including environmental documentation and permitting, is required to move the project forward. Additionally, a contract with Cal Water will be required to obtain treated water for injection. .

6.2.5.24 Beckman Well
The Beckman well was a project implemented in the early 2000’s as a collaboration between the East Bay Municipal Utilities District and SEWD along the Mokelumne Aqueduct. SEWD is looking assess the current status of the well and determine the requirements to revive it as a functioning aquifer storage and recovery (ASR) well. If implemented, this project would recharge surface water from the East Bay Mud Aqueduct or the New Hogan Reservoir (Calaveras River EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-51
Projects and Management Actions November 2024
water) for storage in the aquifer, to be later extracted during drought periods. Estimates of the amount of water available for recharge are currently unknown.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: To be determined Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: This project is still in the early project development stages. SEWD is looking to hire a company to understand the current status of the well and what would be required to revive it as a function ASR well.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: The initiation and completion dates for this project are currently unknown. If implemented, this project may be completed by 2028.

Expected Benefits and Evaluation: This project is anticipated to directly recharge water during wet periods for storage and later extraction. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: This project would recharge surface water from the East Bay Mud Aqueduct or the New Hogan Reservoir (Calaveras River water).

Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $20,000 million in capital costs.

Costs for annual operations and maintenance are unknown. SEWD and MICUP will provide funds for this project.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: The proposed well needs to be assessed to determined its suitability for use as an injection well. Therefore, the status of the well will determine if the project is feasible for construction.

6.2.5.25 West Linden Project
This project would provide surface water for in-lieu and direct recharge in the area west of Linden, where the groundwater table is at its lowest. Surface water would be provided using Mokelumne Aqueduct Water and New Hogan Reservoir (Calaveras River) water. Estimates of the amount of water that would be available for direct or in-lieu recharge range from 5,000-60,000 AF/year, depending on water year type and availability.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: In-Lieu/ Direct Recharge
Estimated Groundwater Offset and/or Recharge: 5,000 - 60,000 AF/year EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-52
Projects and Management Actions November 2024
Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct and/or in-lieu recharge opportunities.

Project Status: This project is still in the early planning and design stages. SEWD is working on discussion with MICUP and EBMUD to discuss collaboration and funding.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: If implemented, this project may be completed by 2035.

Expected Benefits and Evaluation: This project is anticipated to provide direct and in-lieu recharge opportunities for the groundwater basin in areas where the groundwater table is typically at its lowest. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: Mokelumne Aqueduct Water and New Hogan Reservoir (Calaveras River) water
Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project and approach for meeting costs are unknown at this time.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: Implementation of this longer term project will be based on long-term management or changing needs of the GSA or Subbasin and coordination with participating partners.

6.2.5.26 Water Supply Enhancement Project - Direct Recharge This project would use surface water from the New Hogan distribution system to implement direct recharge projects, such as dry wells or recharge basins along SEWD’s distribution system. SEWD is currently engaging with landowners of potential sites to assess their interest in participating. At this stage, the estimated volume of water that could be recharged remains undetermined.

Project Summary
Submitting GSA: Stockton East Water District
Project Type: Direct Recharge
Estimated Groundwater Offset and/or Recharge: To be determined Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by enhancing direct recharge opportunities.

Project Status: This project is still in the early project development stages.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: If implemented, this project may be completed by 2030.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-53
Projects and Management Actions November 2024
Expected Benefits and Evaluation: This project is anticipated to directly recharge the groundwater basin in areas along SEWD’s distribution area. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

How Project Will Be Accomplished/Evaluation of Water Source: New Hogan Reservoir (Calaveras River) water Legal Authority: SEWD is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SEWD is also a GSA with authority on groundwater pumping.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project are unknown at this time. Costs would be provided by SEWD and any grants the District is able to secure.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: This project is in the preliminary stages.

Additional analyses need to be conducted to identify appropriate areas for recharge, and coordination agreements with property owners and/or land acquisitions will be required before the project can move forward.

6.2.5.27 SSJID Water Master Plan - System Improvements
Several thousand acres within SSJID are unable to utilize surface water or have limited access due to capacity issues and evolving irrigation practices. To address this, SSJID has identified numerous capital projects aimed at improving capacity and utilizing flow controls to accommodate additional growers returning to SSJID surface water deliveries.

SSJID has embarked on a comprehensive Water Master Plan to address its aging infrastructure and make strategic improvements to its irrigation systems. The plan includes increasing lateral capacity, constructing new reservoirs, and implementing additional SCADA controls. In total, SSJID has identified $191 million in capital improvements. To fund these projects, SSJID completed a substantial Prop 218 rate increase in July 2023. Through 2040, SSJID expects to implement several capital projects outlined in the Water Master Plan. Estimates of the benefit to the groundwater basin range from 10,000 – 15,000 AF/year.

Project Summary
Submitting GSA: South San Joaquin GSA
Project Type: In-lieu Recharge
Estimated Groundwater Offset and/or Recharge: 10,000 - 15,000 AF/year Measurable Objective Expected to Benefit: This project addresses chronic lowering of groundwater levels in the Subbasin by providing surface water to additional customers in the District for use in-lieu of groundwater.

Project Status: A feasibility study for this project has been completed.

Required Permitting and Regulatory Process: The required permitting and regulatory process for this project has not been determined.

Time-table for Initiation and Completion: SSJID is anticipating completing several projects outlined in the Water Master Plan through 2040.

Expected Benefits and Evaluation: This project is anticipated to provide surface water to district growers for use in-lieu of groundwater. This will indirectly recharge the groundwater basin in areas that are geographically dispersed throughout the Subbasin. Benefits to groundwater levels will be evaluated through ESJWRM model simulations.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-54
Projects and Management Actions November 2024
How Project Will Be Accomplished/Evaluation of Water Source: The identification of water source will occur as projects develop but will be utilizing SSJID permitted water supplies.

Legal Authority: SSJID is a local agency with its own enabling legislation established to serve water for agricultural and municipal demands. SSJID is also a GSA with authority on groundwater pumping.

Estimated Costs and Plans to Meet Costs: The estimated costs for this project include $30-40 million in capital costs.

Costs for annual operations and maintenance are unknown at this time. Funding will be provided through existing revenue sources such as hydropower generation, user fees, and water charges. Enhanced sources such as increased user fees and additional water transfers may also contribute. External funding may also be secured through grants, earmarks, or other water transfers.

Circumstances for Implementation: The circumstances for implementation of this project are unknown at this time.

Trigger for Implementation and Termination: The triggers for implementation and termination of this project are unknown at this time.

Process for Determining Conditions Requiring the Project have Occurred: The feasibility study to identify potential inlieu recharge projects has been completed. Implementation of projects identified in the study will be based on longterm management or changing needs of the GSA or Subbasin and the availability of funding and willing growers.

6.2.6 Mokelumne River Loss Study
The Mokelumne River Loss Study, proposed by NSJWCD, will study reaches of the Mokelumne River downstream of Camanche Reservoir to better understand and account for losses due to percolation, evaporation, riparian evapotranspiration, and more to inform management actions and SGMA basin accounting. Results of the study will be used to support model refinement and validation (described in Section 7.4.1) in this region and will help to fill the interconnected surface water data gap discussed in Section 4.7.3. The project cost about $100,000 and will take two years to complete once funding has been identified.

6.2.7 Notification Process
Notification and public outreach around projects will be conducted at the GSA level. GSAs will post project updates to their websites to notify the public that the implementation of projects is being considered or has been implemented.

This will include a description of the actions to be taken. These updates will also be provided to the other GSAs and will be published on the ESJGWA website and other appropriate locations. Additional noticing for the public will be conducted consistent with permitting requirements in the case of the enactment of fees or assessments. Outreach may include public notices, meetings, website or social media presence, and email announcements.

6.3 MANAGEMENT ACTIONS
Management actions are generally administrative, locally implemented actions that the GSAs could take that affect groundwater sustainability. Management actions typically do not require outside approvals, nor do they involve capital projects. No management actions currently related to pumping activities or groundwater allocations have been completed to date for the Subbasin; however, Subbasin GSAs are planning to develop a Demand Management Program that will provide needed structure and flexibility to implement such demand-side management actions in the future if need is determined. As part of the development of the demand reduction program, public outreach and education on the potential structure of the program, as well and feasible monitoring and enforcement mechanisms, will be conducted as necessary to enable a successful program. Outreach could include public notices, meetings, website or social media presence, workshops and email announcements.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-55
Projects and Management Actions November 2024
There are a number of conservation and demand management actions currently in place in the Subbasin, including those outlined in Urban Water Management Plans (UWMPs) and Agricultural Water Management Plans (AWMPs), as identified below.
• CCWD Urban Water Management Plan (Demand management measures include water waste prevention ordinance, metering, conservation pricing, public education and outreach, programs to assess and manage distribution system real loss, water conservation program coordination and staffing support, rebates and giveaways) (CCWD, 2021).
• City of Lodi Urban Water Management Plan (Demand management measures include water waste prevention ordinance, metering, conservation pricing, public education and outreach, programs to assess and manage distribution system loss, water conservation program coordination and staffing support, rebate program) (City of Lodi, 2021)
• Cal Water Urban Water Management Plan (Demand management measures include water waste prevention ordinance, metering, conservation pricing, public education and outreach, programs to assess and manage distribution system real loss, water conservation program coordination and staffing support, and other demand management measures) (Cal Water, 2021).
• City of Ripon Urban Water Management Plan (Demand management measures include water waste prevention ordinance, metering, conservation pricing, public education and outreach, programs to assess and manage distribution system real loss, water conservation program coordination and staffing support, and other demand management measures) (City of Ripon, 2017).
• SEWD Urban Water Management Plan (Demand management measures include metering, public education and outreach, water conservation program coordination and staffing support, asset management, and wholesale supplier assistance programs) (SEWD, 2021).
• SSJID Urban Water Management Plan (Demand management measures include water waste prevention ordinance, metering, conservation pricing, public education and outreach, programs to assess and manage distribution system real loss, water conservation program coordination and staffing support, asset management, wholesale supplier assistance programs, and other demand management measures) (SSJID, 2021).
• City of Stockton Urban Water Management Plan (Demand management measures include water waste prevention ordinance, metering, conservation pricing, public education and outreach, programs to assess and manage distribution system real loss, water conservation program coordination and staffing support, water survey programs for residential customers, residential plumbing retrofit, conservation programs for commercial, industrial, and institutional accounts; and landscape conservation programs and incentives) (City of Stockton, 2021).
• OID Agricultural Water Management Plan (Efficient water management practices include delivery measurement accuracy, volumetric pricing, alternative land use, recycled water use, capital improvements for on-farm irrigation systems, incentive pricing structures, increasing water ordering and delivery flexibility, supplier spill and tailwater recovery systems, increase planned conjunctive use, automate canal control, facilitate customer pump testing, designate water conservation coordinator, provide for availability of water management services, evaluate supplier policies to allow more flexible deliveries and storage, and evaluate and improve efficiencies of supplier’s pumps) (OID, 2021). • SEWD Agricultural Water Management Plan (Efficient water management practices include water measurements, volume-based pricing, alternate land use, recycled water use, on-farm irrigation capital improvements, incentive pricing structure, infrastructure improvement, order/delivery flexibility, supplier spill EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-56
Projects and Management Actions November 2024
and tailwater systems, conjunctive use, automated canal controls, customer pump test/evaluation, water conservation coordinator, water management services to customers, identify institutional changes, and supplier pump improved efficiency) (SEWD, 2021).
• SSJID Agricultural Water Management Plan (Efficient water management practices include delivery measurement accuracy, volumetric pricing, alternative land use, recycled water use, capital improvements for on-farm irrigation systems, incentive pricing structures, lining or piping of distribution system and construction of regulating reservoirs, increasing water ordering and delivery flexibility, supplier spill and tailwater recovery systems, increase planned conjunctive use, automate canal control, facilitate pump testing, designate water conservation coordinator, provide for availability of water management services, evaluate supplier policies to allow more flexible deliveries and storage, and evaluate and improve efficiencies of supplier’s pumps) (SSJID, 2021).

In the 2024 GSP Amendment, two new management actions were added:
• Dewatered Domestic Well Mitigation Program: This program will provide a formalized process through which the ESJGWA can track and mitigate the dewatering of domestic wells as a result of subbasin management activities. The program was adopted by the ESJGWA in September 2024 and is expected to be implemented starting in 2025. Additional detail on this program can be found in Appendix 3-J. • Demand Management Program: A framework for a Subbasin-wide Demand Management Program will be developed as part of this management action. This program will serve as a backstop that can be activated if projects fall short of meeting expected supply-side targets. The program will be developed and preliminarily implemented, if needed, by GSAs between 2025 and 2030. The program is expected to rely on an iterative process that incorporates analysis of hydrologic conditions, assessment of PMA progress, development of a demand reduction target using ESJWRM, and distribution of demand reduction goals amongst the GSAs. An initial program outline is included in Appendix 6-B, but the program is expected to evolve significantly by 2030.

Additional management activities are discussed in Chapter 7: Plan Implementation, including:
• Monitoring and recording of groundwater levels and groundwater quality data • Maintaining and updating the Subbasin Data Management System (DMS) with newly collected data • Addressing identified data gaps
• Annual monitoring of progress toward sustainability
• Annual reporting of Subbasin conditions to DWR as required by SGMA

6.4 ADAPTIVE MANAGEMENT STRATEGIES
Although the ESJGWA does not provide direct authority to require GSAs to implement projects, the GWA will be working on GSA-level water budgets and will be requesting annual or biannual reports to evaluate progress. It was stated in the 2020 GSP that if the projects do not progress, or if monitoring efforts demonstrate that the projects are not effective in achieving stated recharge and/or offset targets, the GWA will convene a working group to evaluate supply-side and demand-side management actions such as the implementation of groundwater pumping curtailments, land fallowing, etc. In the 2024 GSP Amendment, a new management action is being added to the GSP to formalize the development of a Demand Management Program that can be used as a backstop, if necessary, to ensure the recovery of the principal aquifer if the Subbasin falls short on project implementation and groundwater offset targets. It is the still the overall theme and goal of the ESJ GSP to first implement PMAs to manage overdraft and reach basin sustainability. However, this management action is intended to respond to direction provided by DWR and to outline the demand side action that would be taken if supply side actions are not effective in meeting overall basin sustainability goals. Based on comments from DWR in their November 18, 2021 Consultation Initiation Letter (Letter) requesting additional detail on management actions that could be implemented, the ESJGWA has developed descriptions of EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-57
Projects and Management Actions November 2024
adaptive management measures to be considered for implementation if projects are demonstrated to not be effective in achieving Subbasin sustainability targets. After implementation of the Category A projects (as described herein and in Chapter 2 of this revised GSP), the adaptive management actions identified below could be implemented in coordination with Category B projects if additional measures are required to sustainably manage groundwater in the Subbasin. These alternative adaptive management actions are programs that are not currently ready for implementation, are in the early planning stages, and do not have firm schedules for development but rather would be implemented as needed sometime after 2031 following reevaluation of Subbasin sustainability during the 5-Year Periodic Evaluation in 2030. The following describes these potential programs as they are currently contemplated; none of these programs are planned for implementation in the Subbasin at this time. • Groundwater Extraction Fee with Land Use Modifications – A groundwater extraction fee or groundwater production charge could be collected from entities that own or operate an agricultural well. Revenue from these fees could then be used to pay for a variety of activities such as the construction of water infrastructure, groundwater conservation initiatives, proper construction and destruction of wells to prevent contamination, groundwater recharge and recovery projects, purchase of imported water or other supplies to replenish the groundwater basin through direct or in-lieu recharge, and/or purchasing and permanent fallowing of marginally-productive agricultural lands dependent on groundwater. Several agencies in California have already implemented such a program and have seen success in utilizing revenue to benefit the local groundwater basin. A similar methodology could be applied within the Eastern San Joaquin Subbasin. • Rotational Fallowing or Permanent Fallowing of Crop Lands – Agricultural water use can be temporarily reduced by fallowing crop lands. While this can have economic impacts to a region, the benefits may also include improved water supply reliability, improved groundwater quality, increased groundwater levels, reduced subsidence, and operational flexibility. Rotational fallowing of crop lands reduces the economic impacts to any one area by rotating the areas of fallowing. This management action could be combined with a recharge project through the application of surplus water supplies to the fallowed lands resulting in in-lieu groundwater recharge or the repurposing of the permanently fallowed lands to create wildlife habitat or some other land use benefit that is not reliant on groundwater as a supply. This management action could be implemented, if needed, to help the Subbasin work towards its sustainability goals. However, the rules by which this management action would be implemented would have to be developed by the GSAs within the Subbasin.
• Conservation Programming for Demand Reduction – A demand reduction measure serves to reduce water demand, surface water losses, and/or nonessential water uses. Demand reduction measures may include a conservation rate structure or a uniform rate structure with a conservation program that achieves demand reduction. Conservation and demand management programs have been a priority for utility providers across the state for decades. Water conservation programs can by implemented by utilities to help offset the increasing demands being placed on water resources. Actions that may be considered a demand reduction measure include, but are not limited to, the following activities:
o Conservation rates
o Water efficient landscaping
o Smart meters
o Water efficient fixtures and appliances
o Water conservation education effort
Many of the GSAs in the Subbasin are currently implementing conservation programming for demand reduction. Under this management action, additional resources would be directed toward conservation programming for demand reduction such that these programs can be enhanced or expanded. .

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-58
Projects and Management Actions November 2024
Additionally, the ESJGWA will conduct regular ‘calls for projects’ to identify additional potential projects and management actions that may be implemented to support Subbasin sustainability, and will, as part of this process, update information regarding projects already identified herein.

6.5 SIMULATION OF PROJECTS AND MANAGEMENT ACTIONS IN PROJECTED WATER BUDGET The November 18, 2021 Letter from DWR identified two potential deficiencies with the Subbasin GSP which may preclude DWR’s approval of a 2022 Revised GSP, as well as potential corrective actions to address each potential deficiency. Potential Deficiency 1 related to the GSP’s requirement of two consecutive non-dry (i.e., below normal, above normal, or wet) water year types and the exclusion of dry and critically dry water-year types in the identification of undesirable results. (Please see Chapter 3, Sustainable Management Criteria, for revisions that addressed this deficiency). Potential Deficiency 1 also requested additional detail on how projects and management actions, in conjunction with the proposed chronic lowering of groundwater levels sustainable management criteria, will offset drought related groundwater reductions and avoid significant and unreasonable impacts. Specifically, Potential Correction Action 1(b) stated that the GSP "fails to identify specific extraction and groundwater recharge management actions the GSAs would implement or otherwise describe how the Subbasin would be managed to offset...dry year reductions of groundwater storage”. As a Potential Corrective Action, the following is suggested: “The GSP should be revised to include specific projects and management actions the GSAs would implement to offset drought year groundwater level declines.”
As part of the process to respond to DWR, the ESJGWA worked with each GSA individually to update GSP project descriptions with new information that had become available in the two years after the GSP was first adopted in 2020.

These revised projects were divided into two categories: Category A projects (projects that are likely to advance in the next five years and have existing water rights or agreements) and Category B projects (projects that are not anticipated to advance in the next five years, but could be leveraged in the future, particularly if Category A projects do not fully achieve stated recharge and/or offset targets). Category A projects and Category B projects are shown in Table 6-1, along with project assumptions. As part of the 5-year Periodic Evaluation, the ESJGWA again worked with each GSA to update the GSP project and management action descriptions included in the 2022 Revised GSP, to add new projects and management actions to the PMA list, and to remove any project that is no longer feasible. This updated information is also reflected in Table 6-1. Please see Chapter 2, Basin Setting, and Appendix 2-D for information as to how the Category A projects were simulated in the projected water budget and for a description of their effectiveness on addressing overdraft in the Subbasin.1 Category B projects may be elevated to a Category A project should feasibility studies or other assessments demonstrate a viable project, if water rights or contracts are firmly identified, if partnerships are formed, and if economic evaluation demonstrate that the projects are cost effective.

6.6 POTENTIAL AVAILABLE FUNDING MECHANISMS
The SWRCB has identified potential funding mechanisms that can be used toward the planning, construction, and implementation of GSP projects. Several funding types may be applicable to the current list of projects and management actions and to potential future projects for the Eastern San Joaquin GSP, including projects included in an Integrated Water Resource Management Plan (IRWMP), projects addressing drinking water, stormwater recharge, water recycling projects, wastewater and system improvement projects, and projects that focus on DAC or SDAC areas.

The range of applicable projects, per SWRCB Funding Opportunities fact sheet and per Water Code §10727.4(h), include recharge projects, groundwater contamination remediation, water recycling projects, in-lieu use, diversions to storage, conservation, conveyance, and extraction projects. Additional projects or management actions outside of this 1 City of Stockton’s Advanced Metering Infrastructure project was added as a Category A project during the Public Comment period of the 2024 GSP Amendment. Therefore, it is not included in the PMA simulation results shown in the 2024 GSP Amendment. It will be simulated in future GSP Amendments.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 6-59
Projects and Management Actions November 2024
list may also be applicable if a GSA determines it will help achieve the sustainability goal for the Subbasin (see GSP Regulations §354.44). Many of the available funding mechanisms accept applications on a continuing basis. Table 6-2 provides an overview of the project types and available funding and programs as well as important dates to consider for implementation. Funding options are explained in greater detail in Chapter 7: Plan Implementation.

Table 6-2: Overview of Project Types and Available Funding Mechanisms Project Type and
Purpose Funding Type Program Important Dates
Water recycling projects Planning and
construction grants
and financing
Water Recycling
Funding Program
(CWSRF)
Planning applications accepted on
continuous basis. Construction
applications received by December
31st of each year will be used to
develop a priority score. Projects
which receive a priority score equal
to or greater than the yearly
fundable list cutoff score will be
placed on the fundable list for the
upcoming fiscal year.

Wastewater treatment for
DAC & SDAC projects
Planning and
construction grants
and financing
Small Community
Grant Fund
(CWSRF)
Applications accepted on
continuous basis.

Drinking Water Planning and
implementation grants
Groundwater Grant
Program (SDWSRF)
There are no solicitations currently
available under this program.

Public water system
improvements
Planning and
construction grants
and financing
Drinking Water
Grants
Applications accepted on
continuous basis.

Stormwater recharge
projects
Implementation grants Storm Water Grant
Program
There are no solicitations currently
available under this program.

IRWM projects (included
and implemented in an
adopted IRWMP)
Implementation Grant IRWM
Implementation
Grant Program
There are no solicitations currently
available under this program.

Sustainable
Groundwater
Management
Planning and
implementation grants
SGMA-related grant
program
There are no solicitations currently
available under this program.

Various Planning and
implementation grants
WaterSMART grant
program
There are multiple programs under
the USBR WaterSMART grant
program with varying requirements.

Individual projects should visit
grants.gov to look at open funding
opportunities.

EXHIBIT 1
Draft Groundwater Sustainability Plan 7-1
Sustainable Management Criteria July 2019

7. PLAN IMPLEMENTATION
The Eastern San Joaquin Groundwater Sustainability Agency (GSAs) will work together in mutual cooperation to implement the Eastern San Joaquin Subbasin Groundwater Sustainability Plan (GSP) in compliance with the Sustainable Groundwater Management Act (SGMA). Implementing the GSP includes implementation of the projects and management actions included in Chapter 6: Projects and Management Actions, as well as the following items:
• Eastern San Joaquin GSP implementation program management • Eastern San Joaquin GSAs administration and management • Implementation of the monitoring program and annual reporting • Data collection and analysis
• Public outreach
• Development of 5-year Periodic Evaluation and GSP amendments as needed • Grant writing
This chapter provides a description of the above items, including contents of the annual and 5-year Periodic Evaluation reports that will be provided to the Department of Water Resources (DWR) as required under SGMA regulations.

7.1 IMPLEMENTATION SCHEDULE
Development and adoption of an initial GSP by the January 31, 2020 deadline was a large task. During GSP development, the Eastern San Joaquin Groundwater Authority Board of Directors (ESJGWA Board) identified key areas that would need to be further developed as GSP implementation continued.

Table 7-1 illustrates the Eastern San Joaquin GSP’s schedule for implementation from 2020 to 2040, highlighting the high-level activities anticipated for each 5-year period. A more detailed schedule is provided in Figure 7-1, updated to reflect current understanding as of the 2024 GSP Amendment. These activities are necessary for ongoing GSP monitoring and updates; Figure 7-1 also includes tentative schedules for projects and management actions. Additional details on the activities included in the timeline are provided in the activities’ respective sections of this GSP.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 7-2
Projects and Management Actions November 2024
Table 7-1: GSP Schedule for Implementation 2020 to 2040 2020 2025 2030 2035 2040
Monitoring and
Reporting Project Implementation Prepare for Sustainability Implement Sustainable
Operations
• Establish monitoring
networks
• Construct new wells
• Model refinement
and verification
studies
• Initial project
implementation
• Ongoing outreach
regarding GSP and
projects
• GSAs conduct
5-year periodic
evaluation/update
• Project
implementation
continues
• Model refinement
continues as
needed
• Demand
management
policy/plan
developed
• Demand reduction
implemented where
possible
• Monitoring and
reporting continue
• Outreach regarding
GSP and projects
continues
• GSAs conduct
5-year periodic
evaluation/update
• Longer-term/
conceptual project
evaluation
• Project
implementation
continues
• Demand
management
policy/plan
implementation
begins
• Model refinement
continues as
needed
• Monitoring and
reporting continue
• Outreach continues
• GSAs conduct 5-year
periodic
evaluation/update
• Demand management
policy/ plan
implemented as
needed
• Project
implementation
completed
In the five years since the 2020 GSP was adopted, the ESJGWA has dedicated significant resources to the tasks identified in the first column in Table 7-1. A high-level summary of these efforts is summarized below. For a current understanding of GSP implementation work, please consult the most recent Annual Report and 5-Year Periodic Evaluation.
• Establish and improve monitoring networks
o Three additional wells were added to the groundwater level Representative Monitoring Network (RMN), for a total of 23 representative monitoring wells. o The water quality RMN was expanded into a larger combined network, which now includes 2 new wells in Stockton, 3 new wells from the groundwater level RMN, one nested well from the previous (2020) broad monitoring network for water quality, and five additional wells that fill data gaps on the eastern and southern portions of the Subbasin, for a total of 11 wells. Chloride will also be monitored at these wells in addition to total dissolved solids going forward. o The seawater intrusion sustainable indicator was deemed an inapplicable sustainability indicator, and the associated sustainable management criteria and monitoring were removed from the GSP. o A new RMN for subsidence was established in the 2024 GSP Amendment. Direct subsidence monitoring will occur at four continuous global positioning system (CGPS) stations and 6 survey benchmark locations going forward. Basin-wide InSAR will also be downloaded and analyzed on an annual basis as part of monitoring for subsidence in the Subbasin.

EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 7-3
Projects and Management Actions November 2024
o A new RMN for interconnected surface water was established in the 2024 GSP Amendment. This new network includes 6 groundwater levels RMN wells that are within 5 miles of streams, 5 new wells installed specifically for interconnected surface water monitoring, and 1 new well installed in the Delta. Stream gages and other shallow wells adjacent to streams will also be analyzed, but do not have sustainability criteria established.
• Construct new wells
o Constructed two new multi-completion wells through the Technical Support Services grant with DWR in the NSJWCD and SEWD service areas (2021)
o Constructed five new wells through the Prop 1 SGM grant through DWR to capture information related to interconnected surface waters (2022)
o Constructed one new multi-completion well in the Delta (northwestern) area of the Subbasin (2024) • Model refinement and verification studies
o Extended hydrology as part of the development of the Annual Reports (2019, 2020, 2021, 2022, 2023)
o Major model update and calibration (2021-2022)
o New model scenarios development and calibration (2022) o Major model update and calibration (2024)
• Project implementation
o CCWD Automated Metering Infrastructure (AMI) Replacement and Conversion has been completed (2022).
o Construction is completed for the White Slough Water Pollution Control Facility Expansion project (2020).
o Phases 1, 2 and 3 completed for the NSJWCD South System Modernization project (2024). o Pilot Dream Project was completed in February 2024 for the South System Groundwater Banking with East Bay Municipal Utilities District project.
o Phase 1A was constructed and began operation for the NSJWCD North System Modernization/Lakso Recharge project (2024).
o Tecklenburg Recharge Project began operation in 2023 and is substantially completed. o One agreement was executed in 2024 with an existing riparian pumper for the NSJWCD Private Pump Partnerships project.
o OID in-lieu and Direct Recharge program began deliveries of surface water to be used in-lieu of groundwater in 2023.
o OID and SSJID long-term transfer to SEWD was approved in 2023 and is set to begin operation in non-wet years.
o Construction on the Lake Grupe in-lieu recharge project has been completed (2023). o SEWD completed conversion of 2,505 acres to surface water through the SEWD Surface Water Implementation Expansion project (2024).
o Construction began on the West Groundwater Recharge Basin (2024). o The City of Stockton Groundwater Recharge Basin design is in progress. o The City of Stockton Advanced Metering Infrastructure was contracted in March 2024. • Ongoing outreach regarding GSP and projects
o GSA-specific targeted outreach to their constituencies regarding SGMA and ongoing projects to support groundwater sustainability
o Ongoing webpage updates
o Public survey to inform future outreach and engagement activities o Public meetings and open house during development of the 2024 GSP Amendment EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 7-4
Plan Implementation November 2024
Figure 7-1: GSP Implementation Schedule
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 7-5
Plan Implementation November 2024
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EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 7-6
Plan Implementation November 2024

7.2 IMPLEMENTATION COSTS
In implementing the GSP, the GSAs will incur costs which will require funding. Table 7-2 summarizes these activities and their estimated costs. The areas associated with Subbasin-wide management and GSP implementation will be borne by the ESJGWA through contributions from the member GSAs under a cost-sharing arrangement developed following adoption of the 2020 GSP. Projects will continue to be administered by the GSA project proponents. GSAs may elect to implement projects individually or jointly with one or more GSAs, or with the ESJGWA.

The table includes both Category A and Category B projects. Both category types are planned projects. Category A projects however, meet the following criteria:
• Are likely to advance by 2030
• Have necessary water rights or agreements in place
Category B projects are not anticipated to advance in the next five years, but could be leveraged in the future, particularly if Category A projects do not fully achieve stated recharge and/or offset targets or do not produce a response as simulated in the model.

Table 7-2: Costs to GSAs and GSP Implementation Costs
Activity Estimated Cost1
GSP Implementation and Management for GSAs
Monitoring and Reporting
Monitoring $150,000 - $175,000 (annually)
Annual Reporting $65,000 - $90,000 (annually)
Data Management System Updates $0 - $125,000 (as-needed, annually) Data Collection and Analysis
Model Refinements $0 - 100,000 (annually)
Additional Wells if needed $600,000 (as needed)
Administrative Actions $140,000 - $230,000 (annually)
Developing 5-Year Evaluation Reports $800,000 - $2,000,000 every 5 years Public Outreach and Website Maintenance $35,000 - $60,000 (annually) Grant Writing By application type:
$45,000 - $60,000 (State)
$50,000+ (Federal)
Implementing GSP: Projects (Category A)
Lake Grupe In-Lieu Recharge $2.3 million (one time)
$330,000 (annually)
SEWD Surface Water Implementation Expansion $750,000 (one time) $100,000 (annually)
White Slough Water Pollution Control Facility
Expansion
$6 million (one time) – complete
$4,664 (annually)
CSJWCD Capital Improvement Program $50,000 (annually)
EXHIBIT 1
2024 Groundwater Sustainability Plan Amendment 7-7
Plan Implementation November 2024
NSJWCD South System Modernization Phase 1&2: $7 million (one time) $200,000 (annually)
Phase 3: $4 million (one-time), $200,000
(annually)
Phase 4: $8 million (one-time), $200,000
(annually)
Future Phases: $10-20 million (one-time),
$200,000 (annually)
Long-term Water Transfer to SEWD and
CSJWCD
Up to $9 million (annually)
South System Groundwater Banking with East
Bay Municipal Utilities District (EBMUD)
Phase 1: $3,000,000 (one-time)
Phase 2: Estimated $5-15 million (one-time),
annual cost to be determined
NSJWCD North System Modernization/Lakso
Recharge
$4,000,000 (one-time)
$100,000 (annually)
Tecklenburg Recharge Project Phase 1: $750,000 (one-time), $100,000 (annually)
Phase 2: $1,500,000 (one-time), $100,000
(annually)
City of Stockton Phase 1: Groundwater
Recharge Project
$11,500,000 (one-time), annual costs to be
determined, as of 2024.

West Groundwater Recharge Basin To be determined, as of 2024.

NSJWCD Private Pump Partnerships To be determined, as of 2024.

Oakdale Irrigation District In-lieu and Direct
Recharge Project
To be determined, as of 2024.

City of Stockton Advanced Metering
Infrastructure
$17,000,000 (one-time), annual costs to be
determined, as of 2024.

Implementing GSP: Projects (Category B)
City of Manteca Advanced Metering
Infrastructure
$650,000 (one time)
$300,000 (annually)
City of Lodi Surface Water Facility Expansion
and Delivery Pipeline
$ 4 million (one time)
$2,340,000 (annually)
BNSF Railway Company Intermodal Facility
Recharge Pond
$ 50,000 (annually)
Manaserro Recharge Project Approximately $500,000 (one-time) $50,000 (annually)
City of Escalon Wastewater Reuse To be determined, as of 2024.

City of Ripon Surface Water Supply To be determined, as of 2024.

City of Escalon Connection to Nick DeGroot
Water Treatment Plant
To be determined, as of 2024.

Farmington Dam Repurpose Project To be determined, as of 2024.

Mobilizing Recharge Opportunities (MICUP) $2,700,000 (one-time) To be determined (annually)
NSJWCD Winery Recycled Water To be determined, as of 2024.

SSJID Storm Water Reuse To be determined, as of 2024.