Manteca City Council
December 17, 2024

Conserving California’s Wildlife Since 1870
of surface waters. Identify undesirable results indicators for dry and critically dry water years for all sustainability indicators. iii. Minimum Thresholds and Measurable Objectives: Reconsider minimum thresholds and measurable objectives, accounting for undesirable results for fish and wildlife beneficial uses and users of groundwater and interconnected surface water. Design sustainable management criteria that reflect a ‘Critically Overdrafted’ subbasin designation by seeking to improve current groundwater conditions rather than allowing for continued aquifer depletions over the next two decades. Consider how historical groundwater pumping has impacted stream interconnectivity (Figure 2-7, page 2-106), likely increasing streamflow depletion and reducing baseflows in ESJ Subbasin tributaries. Reduced groundwater baseflow exacerbates high water temperatures in the lower San Joaquin River, and high water temperatures negatively impact listed species such as the Chinook Salmon. Minimum thresholds and measurable objectives should reflect an effort to prevent further degradation to interconnected surface waters and to avoid undesirable results, rather than risk magnifying historical undesirable results through lowered groundwater elevations.

GSA Response to Comments: “See Master Response 2 - ISW” (Appendix 1-J, PDF page 899).

Department Response: The above comment remains relevant.

5. Comment #5 (Monitoring Networks, starting page 4-1): Number, distribution, and frequency of data collection of shallow groundwater monitoring wells are insufficient for analysis of ISW.
a. Issue: The current monitoring network lacks a sufficient number, representative distribution, and frequency of monitoring of shallow groundwater monitoring wells to monitor impacts to environmental beneficial uses and users of groundwater and interconnected surface waters [23 CCR § 354.34(2)]. Few wells are near interconnected surface waters or concentrations of GDEs; therefore, there are few data points on shallow groundwater level trends. These data are critical to understanding groundwater management impacts on fish and wildlife beneficial uses and users of groundwater, including GDEs and interconnected surface water habitats, which are impacted disproportionately by shallow groundwater trends.

Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Craig Altare, Supervising Engineering Geologist
California Department of Water Resources
May 13, 2020

Conserving California’s Wildlife Since 1870
b. Recommendation: Install additional shallow groundwater monitoring wells near GDEs and interconnected surface waters, potentially pairing multiplecompletion wells with streamflow gauges for improved understanding of surface water-groundwater interconnectivity. Monitor wells monthly to capture seasonal trends important to GDEs.

GSA Response to Comments: “Data gaps are discussed in Section 4.7 (Data Gaps) and include identified gaps in the monitoring and analysis of interconnected surface waters and GDEs. The GSP includes a plan for the drilling of up to 12 proposed wells to help resolve identified gaps and enhance future analysis of interconnected surface waters and GDEs. These proposed wells would all measure for both groundwater quality and groundwater levels and include 2 deep, nested wells funded under the TSS application and up to 10 shallow wells drilled by the ESJGWA. If a need for more detail is recognized, the monitoring network will be reevaluated as updates to the GSP occur. Frequency of groundwater level monitoring is cited in the Draft Monitoring Networks and Identification of Data Gaps Best Management Practice. While semi-annual monitoring is required for groundwater levels, DWR guidance recommends monthly sampling of groundwater levels for the Subbasin based on aquifer type, volume of long-term aquifer withdrawals, and recharge potential. The ESJGWA Board determined semi-annual sampling was appropriate as it will capture seasonal highs and lows and that additional monitoring would not necessarily provide additional information on trends” (Appendix 1-J, PDF page 905).

Department Response: The anticipated monitoring network expansion will vastly improve data collection and monitoring. Until such time as the new system is in place, the Department maintains the above concern for insufficient monitoring. The Department will also continue to recommend monthly monitoring of shallow groundwater to better understand the relationships between shallow groundwater trends and fish and wildlife beneficial uses and users of groundwater.

6. Comment #6 (Project and Management Actions; 6.1 Projects, Management Actions, and Adaptive Management Strategies; starting page 6-1): Demand reduction management actions lack emphasis and specificity critical to ESJ Subbasin sustainability goal achievement.
a. Issue: The GSP project and management actions focus on supply augmentation, with only three projects intended to conserve groundwater through metering and systems optimization. Though the GSP reserves the Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Craig Altare, Supervising Engineering Geologist
California Department of Water Resources
May 13, 2020

Conserving California’s Wildlife Since 1870
flexibility to implement demand-side management in the future (page 6-1), there are no specifics as to how the ESJGA or subbasin GSAs would implement demand management. This lack of specificity on how demand will be managed may lead to deprioritization or delayed implementation of demand management actions, which can undermine a basin’s ability to achieve sustainability goals. Considering the ESJ Subbasins’ current unsustainable rate of groundwater consumption as a ‘Critically Overdrafted Basin’ and considering the cost and timing challenges associated with supply augmentation projects, a balanced portfolio approach to achieve groundwater sustainability should include demandmanagement strategies. b. Recommendation: Add specific measures for initiating demand reduction on an earlier timeline in the ESJ Subbasin to account for groundwater pumping lag impacts, supply-augmentation project implementation challenges, and a scaled ramping-down of groundwater use that is a necessary component of San Joaquin Valley long-term groundwater sustainability. Be specific about triggers, timing, and expected outcomes of demand-management actions.

GSA Response to Comments: “See Master Response 5 – Projects” (Appendix 1-J, PDF page 902)
Department Response: Master Response 5 includes the addition of new language in the GSP that promises to convene a working group if projects are not effective in achieving their target recharge or offset targets. The Department remains concerned that this action, in concert with the minimal demand-management actions, may be insufficient to achieve long term sustainability. Therefore, the above comment remains relevant.

CONCLUSION
In conclusion, the Final Eastern San Joaquin Basin GSP has improved GSP transparency by acknowledging several key data gaps. After thorough review, the Department deems the GSP insufficient in its consideration of environmental beneficial uses and users of groundwater, including fish and wildlife and their habitats: GDEs and ISW. The Department recommends that ESJGA address the Departments concerns before the California Department of Water Resources approves the final GSP.

The Department appreciates the opportunity to provide comments on the Final Eastern San Joaquin Basin GSP. If you have any further questions, please contact Briana Seapy by email at [email protected] or at (916) 508-3345.

Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Craig Altare, Supervising Engineering Geologist
California Department of Water Resources
May 13, 2020

Conserving California’s Wildlife Since 1870
Sincerely,
Kevin Thomas
Regional Manager, North Central Region
ec: Joshua Grover, [email protected]
Robert Holmes, [email protected]
Jeff Drongesen, [email protected]
Briana Seapy, [email protected]
California Department of Fish and Wildlife
ec’s: Continued on page 14
Paul Wells, [email protected]
California Department of Water Resources
Brandon Nakagawa, [email protected]
Groundwater Sustainability Agency
Rick Rogers, [email protected]
Erin Strange, [email protected]
National Marine Fisheries Service
Natalie Stork, [email protected]
State Water Resources Control Board
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Craig Altare, Supervising Engineering Geologist
California Department of Water Resources
May 13, 2020

Conserving California’s Wildlife Since 1870
Literature Cited
Barlow, P.M., and Leake, S.A. 2012. Streamflow depletion by wells—Understanding and managing the effects of groundwater pumping on streamflow. U.S. Geological Survey Circular 1376.

California Department of Water Resources (CDWR). 2018. Critically Overdrafted Basins. Available: https://water.ca.gov/Programs/Groundwater-Management/Bulletin118/Critically-Overdrafted-Basins.

Hallock, R.J., R.F. Elwell, D.H. Fry Jr. 1970. Migrations of adult king salmon Oncorhynchus tshawytscha in the San Joaquin Delta as demonstrated by the use of sonic tags. State of California. The Resources Agency. Department of Fish and Game.

Fish Bulletin 151.

Marston, D, C. Mesick, A. Hubbard, D. Stanton, S. Fortmann-Roe, S. Tsao. T. Heyne. 2012. Delta flow factors influencing stray rate of escaping adult San Joaquin River fallrun Chinook salmon (Oncorhynchus tshawytscha). San Francisco Estuary & Watershed Science.

Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Conserving California’s Wildlife Since 1870
Attachment D

CALIFORNIA DEPARTMENT OF FISH AND WILDLIFE COMMENTS ON THE EASTERN SAN

JOAQUIN DRAFT GROUNDWATER SUSTAINABILITY PLAN
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
State of California - Natural Resources Agency

DEPARTMENT OF FISH AND WILDLIFE
North Central Region
1701 Nimbus Road,
Rancho Cordova, CA 95670
www.wildlife.ca.gov
GAVIN NEWSOM. Governor
CHARLTON H. BONHAM, Director
August 23, 2019
Brandon Nakagawa
Eastern San Joaquin Groundwater Sustainability Plan Manager Eastern San Joaquin Groundwater Authority
1810 E. Hazelton Avenue
P.O. Box 1810
Stockton, CA 95201
Email: [email protected]
Subject: COMMENTS ON THE EASTERN SAN JOAQUIN SUBBASIN DRAFT

GROUNDWATER SUSTAINABILITY PLAN
Dear Mr. Nakagawa;
The California Department of Fish and Wildlife (Department) North Central Region is providing comments on the Eastern San Joaquin (ESJ) Subbasin Draft Groundwater Sustainability Plan (GSP) prepared by the Eastern San Joaquin Groundwater Authority (ESJGA)' pursuant to the Sustainable Groundwater Management Act (SGMA). As trustee agency for the State's fish and wildlife resources, the Department has jurisdiction over the conservation, protection, and management offish, wildlife, native plants, and the habitat necessary for biologically sustainable populations of such species (Fish & Game Code §§ 711.7 and 1802).

Development and implementation of GSPs under SGMA represents a new era of California groundwater management. The Department has an interest in the sustainable management of groundwater, as many sensitive ecosystems and species depend on groundwater and interconnected surface waters, including ecosystems on Departmentowned and -managed lands within SGMA-regulated basins. SGMA and its implementing regulations afford ecosystems and species specific statutory and regulatory consideration, including the following as pertinent to Groundwater Sustainability Plans:
^The Eastern San Joaquin GnaundwaterAuthority comprises 17 GroundwaterSustainability Agencies (GSAs):

Calaveras County Water District / Stanislaus County, Califomia Water Service Company, Central Delta Water Agency, Central San Joaquin Water Conservation District, City of Lathrop, City of Lodi, City of Manteca, City of Stockton. Linden County Water District, Lockefbrd Community Services District, North San Joaquin Water Conservation District, Oakdale Irrigation District, San Joaquin County, South Delta Water Agency, South San Joaquin Groundwater Sustainability Agency, Stockton East Water District, Woodbridge Inigation District GSA.

Conserving CciCifomia's ^iOCCife Since 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

• Groundwater Sustainablllty Plans must identify and consider impacts to groundwater dependent ecosystems [23 CCR § 354.16(g) and Water Code § 10727.4(1)]: I
• Groundwater Sustainablllty Agencies must consider all beneficial uses and users of groundwater, including environmental users of groundwater [Water Code §10723.2 (e)]; and Groundwater Sustalnabili^y Plans must identify and consider potential effects on all beneficial uses and users of groundwater [23 CCR §§354.10(a). 354.26(b)(3). 354.28(b)(4),1354.34(b)(2). and 354.34(f)(3)];
• Groundwater Sustainability Plans must establish sustainable management criteria that avoid undesirable results within 20 years of the applicable statutory deadline, including depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water [23 CCR § 354.22 et seq. and Water Code §§ 10721(x)(6) and 10727.2(b)] and describe monitoring networl^s that can identify adverse impacts to beneficial uses of interconnected surface waters [23 CCR § 354.34(c)(6)(D)]: and • Groundwater Sustainability Plans must account for groundwater extraction for all Water Use Sectors including managed wetlancJs, managed recharge, and native vegetation [23 CCR §§ 351(al) and 354.18(b)(3)].

Accordingly, the Department values SGMA groundwater planning that carefully considers and protects groundwater dependent ecosystems (GDE), fish and wildlife beneficial uses, and users of groundwater and Interconnected surface waters.

COMMENT OVERVIEW
The Department Is writing to support ecosystem preservation In compliance with SGMA and its implementing regulations based on Department expertise and best available information and science.
!
The Department believes the GSP does not adequately demonstrate consideration of environmental beneficial uses and users of groundwater in its sustainablllty management criteria nor does It adequately characterize or consider surface watergroundwater connectivity. Accordingly, the Department recommends that ESJGA address these deficiencies before submitting the GSP to the Department of Water Resources(DWR). !

COMMENTS AND RECOMMENDATIONS
The Department comments are as follows:

1. Comment #1 (Plan Area, 1.2.1.1 Summary of Jurisdictlonal Areas and Other Features, pp. 1-18): Department lands are excluded from 'Summary of Jurisdictlonal Areas' narrative as well as from Figure 1-11, which maps other federal and state lands.

Conserving CaGfomia's WiQ£Cife Since 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

a. Issue: The GSP does not identify the jurisdictional boundaries of Department-owned and -managed lands as required by 23 CCR § 354.8(a)(3).
b. Recommendation: Include in Figure 1-11 and the accompanying narrative White Slough Wildlife Area, Woodbridge Ecological Reserve, and Vernalis Ecological Reserve Department lands.

2. Comment #2 (Basin Setting, 2.2.6 Interconnected Surface Water Systems, starting pp 2-97): The nanrative describing the basin's interconnected surface water conditions lacks specifics and contains inconsistencies in mapped surface water-groundwater interconnectivity.
a. Issue:
i. The interconnected surface water conditions narrative lacks estimations of the quantity and timing of streamflow depletions as specified in 23 CCR § 354.16(f).
ii. Figure 2-65 portrays modeled 'losing,' 'gaining,' and 'mixed' stream reaches, and Figure 2-66 portrays modeled 'interconnected and 'disconnected' streams. Figure 2-66 shows modeled stream reaches as 'disconnected,' whereas Figure 2-65 identifies those same reaches as switching between 'losing,' 'gaining,' and 'mixed.' Accompanying narrative suggests that streams are only mapped as 'interconnected' in Figure 2-66 when they are interconnected at least 75% of the time. This 75% threshold for displaying interconnected surface waters excludes reaches of stream that are intermittently connected to groundwater and that may depend on groundwater contributions to meet the needs of instream or riparian beneficial uses and users of interconnected surface waters. b. Recommendation:
i. Identify the estimated quality and timing of streamflow depletions in the ESJ Subbasin. Ifthis information is not available, identify an expeditious path to estimating these values.
ii. Update Figure 2-66 to show all interconnected stream reaches, even ifthey are interconnected less than 25% of the time.

3. Comment #3 (Basin Setting, 2.2.7 Groundwater-Dependent Ecosystems, starting pp 2-100): GDE identification, required by 23 CCR § 354.16(g), is based on methods that risk exclusion of ecosystems that may depend on groundwater. a. Issue: Methods applied to the Natural Communities Commonly Associated with Groundwater (NCCAG) dataset to eliminate potential GDEs are fallible.

Conserving CctRfomia's WiC(£Cife Since 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23. 2019

i. Depth to Groundwater: The removal of potential GDEs with a depth to groundwater greater than 30 feet during (an unspecified season) of 2015 relies on a single-point-in-tinfie baseline hydrology.

Specifically, this 2015 baseline falls several years into a historic drought when groundwater levels throughout the San Joaquin Valley were trending dramatically lovier than usual due to reduced surface water availability. Exclusion of potential GDEs based on a snapshot of groundwater elevations during a historic drought is invalid; because this approach does not consider representative climate conditions or account for GDEs that can survive a finite period of time without groundwater apcess (Naumburg 2005), but that rely on groundwater table recovery for long term survival. ii. Adjacent to Alternate Water Suoplies: The GSP notes that "to be dependent on groundwater there must not be other available water supplies" (GSP pp 2-104). This statement disregard's a GDE's adaptability and opportunistic approach to accessing water in which vegetation may vary reliance on surface water and groundwater between seasons and water years.^ Therefore, the removal of potential GDEs that are within 50 feeit ofirrigated lands, 150 feet of managed wetlands, and 150feet of perennial surfacewaterdoes not consider the potential for GDEs shifting reliance between surface and groundwater. Additionally, vegetation near
interconnected perennial surface waters may depend on sustained groundwater elevations to stabilize the gradient or rate of loss of surface water; meaning ecosystems near interconnected surface waters likely depend on sustainable groundwater elevations and constitute GDEs. Therefore, it is possible that any of these potential GDEs proximate to 'altemate water supplies' rely on groundwater during specific seasons or water years.
b. Recommendations:
i. Depth to Groundwater: Developa hydrologically robust baseline from which to remove 'areas with a depth to groundwater greater than 30 feet' that relies on multiple, climatically representative years of groundwater elevation and that accounts for the inter-seasonal and inter-annual variability of GDE water demand.
2The Department assumes that potential GDEs removed under this step overiie shallow groundwater, otherwise they would have already been removed during the step of excluding potential GDEs that overlie a depth to groundwater of 30+ feet.

Conserving California's WiCcCCifeSince 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

ii. Adjacent to Alternate Water Supplies: Reevaluate potential GDEs previously removed due to proximity to irrigated lands, managed wetlands, and perennial surface waters. Err on the side of inclusivity until there is evidence that the overlying ecosystem has no significant dependence on groundwater across seasons and water year types. Ensure that riparian GDE beneficial users of groundwater and interconnected surface water are carefully considered in the analysis of undesirable results and minimum thresholds for depletions of interconnected surface waters.

4. Comment #4 (Basin Setting, 2.3.5.4 Projected Water Budget, starting pp 2-130):

Projected water budget assumptions may risk overestimating surface water availability and sustainable yield by not relying on best available information [23 COR § 354.18(e)].
a. Issue: Projected surface water budget assumptions may risk overestimating water availability. Overestimation of water availability can result in the overallocation of both surface and groundwater water resources, unnecessarily jeopardizing environmental beneficial users. Two water budget assumptions that do not rely on best available infomriation and that underscore cunrent sustainable yield estimations are as follows:
1) the climate change analysis predicting a net depletion of aquifer storage is not reflected in the projected water budget or estimated sustainable yield, rather it is presented as a separate analysis; and 2) projected surface water deliveries need to be updated to reflect any new regulatory reductions ofsurface water deliveries such as those that may be codified in the State Water Resources Control Board Water Quality Control Plan for the Bay Delta: San Joaquin River Flows and Southem Delta Water Quality.
b. Recommendation: Amend the water budget and sustainable yield: 1) apply climate change estimates to the projected water budget and scale the sustainable yield accordingly; and 2) adjust surface water delivery estimates to reflect any new regulatory compliance.

5. Comment #5 (Sustainable Management Criteria, 3.2.1 Groundwater Levels and

3.2.6 Depletions of Interconnected Surface Water, starting pp 3-1): Groundwater Level and Interconnected Surface Water sustainable management criteria do not protect against undesirable results for fish and wildlife beneficial uses and users of groundwater and interconnected surface waters.
a. Issues:
i. Proxv Metric: Before addressing the individual sustainability criteria for both Groundwater Levels and Depletions of Interconnected Conserving CaCifomia's "WifdCife Since 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

Surface Water, the Department challenges the use of groundwater elevations as a proxy metric for Depletions of Interconnected Surface Water. The GSP does not provide evidence that a "significant correlation exists between groundwater elevations" and Depletions of Interconnected Surface Water [23 OCR §
354.36(b)(1)]. Instead, the GSP backs into the proxy metric by associating the proposed Groundwater Level minimum thresholds with the absence of significant and unreasonable surface water depletions, claiming that historical depletions of interconnected surface water had no associated undesirable results (GSP pp 3- 19). The GSP offers few details to substantiate this claim that historical surface water depletions did not lead to undesirable results, and the GSP does not specify the modeling exercise used to detennine the insignificance of historical surface water depletions. Provided the status of surface water allocations and aquatic ecosystems on rivers in the ESJ basin, the Department contests that any surface water depletions attributable to groundwater pumping are likely to be significant and unreasonable, particularly in the benchmark year of 2015 when groundwater pumping and surface water temperatures were critically high.

Depleted flows in the lower San Joaquin River, many reaches of which are identified as interconnected in the GSP, contribute to increased in-rlver water temperatures. Groundwater extraction from interconnected aquifers contributes to depletion of instream flow (Barlow and Leake, 2012). Low flows and increased water temperatures in the lower San Joaquin River have been
documented to negatively impact Chinook salmon {Oncorhynchus tshawytscha) and steelhead {Oncorhynchus mykiss) (Hallock 1970, Marston 2012). Acknowledging that fish and wildlife beneficial uses and users of groundwater likely experienced undesirable results during historical pumping regimes, especially during critically dry years, the GSP cannot rely on groundwater elevation as a proxy metric for Depletions of Interconnected Surface Water. If a significant correlation is lacking between groundwater elevations and Depletions of Interconnected Surface Water, particulariy at the representative monitoring well locations used to track groundwater elevations in the ESJ Subbasin, then groundwater elevations used as a proxy for surface water depletions may misinform groundwater management activities and pooriy predict instream habitat Conserving CaRfomia's WitcCCife Since 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

conditions for fish and wiidiife species. Accordingly, the application of Groundwater Level sustainable management criteria to Depletions of Interconnected Surface Water is inappropriate, as it is not grounded in a quantifiable and site-specific understanding of surface water-groundwater connectivity as required by 23 CCR § 354.28 (c)(6)(A).
ii. Undesirable Results: Groundwater Level 'undesirable results' and 'effects of undesirable results' do not specify impacts to environmental beneficial users such as terrestrial GDEs (GSP pp 3- 3, 3-4). Additionally, the method used to identify undesirable results for Groundwater Levels (i.e., minimum threshold exceedances in groundwater elevation) is applied to the identification of undesirable results for the Depletions of Interconnected Surface Water without a reasonable justification. The indicator of undesirable results for Groundwater Levels is the measure of 25% of monitoring wells falling below their minimum thresholds for two consecutive (nondry) years, yet the GSP does not prove a relationship between the Groundwater Level identification of undesirable results and the presence of undesirable results for Depletions of Interconnected Surface Water (see Comment #5.a.i). Effectively, the GSP does not connect identification of undesirable results for Depletions of Interconnected Surface Water to effects on interconnected surface water beneficial users per 23 CCR § 354.26 (b)(3). Finally, the GSP notes that groundwater levels that fall below the minimum threshold during hydrologically dry or critically dry years are not considered to be an indicator of undesirable results (GSP pp 3-3). This means proposed Indicators of undesirable results for Groundwater Levels and Depletions of Interconnected Surface Water do not exist for dry water years. This absence of undesirable results indicators for certain water years means beneficial users of groundwater and interconnected surface water may experience significant and unreasonable effects throughout the duration of dry or critical water years before the undesirable results are 'identified' and managed.

Accordingly, there is no groundwater management accountability during the most challenging of years for water resource managers and fish and wildlife beneficial users alike.
iii. Minimum Thresholds and Measurable Obiectives: Minimum thresholds and measurable objectives for Groundwater Levels, and by proxy, for Depletions of Interconnected Surface Water, are not Conserving CdCifomia's WUxfCife Since 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

protective of environmental beneficial uses and users of groundwater and interconnected surface water. Minimum
thresholds allow for a decrease of groundwater elevation from 2015, or a comparable historic low, for all representative monitoring sites (3-7); and measurable objectives are set at historically low groundwater elevations (GSP 3-8). These sustainability criteria suggest that groundwater elevations at all representative wells in the ESJ Subbasin can continue to decrease for the next 20 years, dropping further from historically low groundwater elevations during drought years, without witnessing undesirable results.

The ESJ Subbasin is characterized by DWR as 'Critically Overdrafted,' meaning "continuation of present water management practices [in the basin] would probably result in significant adverse overdraft-related environmental, social, or economic impacts" ("Critically"). However, according to the GSP, there are no areas within the basin that are considered to have 'significant and unreasonable existing issues' (GSP pp 3-4), therefore minimum thresholds allow for continued groundwater depletions.

Conceptually, there is a disconnect between the ESJ's 'Critically Overdrafted' designation and the GSP's claim that the basin has not experienced undesirable results, nor will it if groundwater levels continue to decrease. More specifically, the Department believes historical declines in terrestrial and aquatic groundwater dependent ecosystem viability, exacerbated by recent drought years, are evidence of undesirable results and further groundwater decline will undoubtedly lead to significant and unreasonable effects on fish and wildlife beneficial uses and users of groundwater and interconnected surface waters under the proposed sustainable management criteria. For example, further streamflow depletion attributable to groundwater pumping that lowers groundwater levels to meet minimum thresholds or evenjmeasurable objective may further compromise in-stream temperature targets in the lower San Joaquin River, adversely impacting in-stream species (see Comment #5.a.i). Accordingly, the Department does not believe groundwater levels above the proposed minimum thresholds and below the proposed measurable objectives (in the margin of operational flexibility) will allow the basin to achieve sustainability, particularly with respect to avoiding undesirable results for fish and Conserving California's ^ittCCifeSince 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

wildlife beneficial uses and users of groundwater and
Interconnected surface water.
b. Recommendation:
i. Proxy Metrics: To justify use of groundwater elevations as a proxy metric for Depletions of Interconnected Surface Water, the GSP should either specify how groundwater elevations are significantly correlated to surface water depletions; or define an expeditious path to identifying the location, quantity, and timing of surface water depletions caused by groundwater use, per 23 CCR §
354.28(c)(6)(A), to better informsustainability criteria for Depletions of Interconnected Surface Water.
ii. Undesirable Results: Specify Groundwater Level 'undesirable results' and 'effects of undesirable results' for environmental beneficial users of groundwater and interconnected surface water.

Specify undesirable result indicators for Depletions of Interconnected Surface Water that are relevant to beneficial users of surface waters. Identify undesirable results indicators for dry and critically dry water years for all sustainability indicators. ill. Minimum Thresholds and Measurable Obiectives: Reconsider minimum thresholds and measurable objectives, accounting for undesirable results for fish and wildlife beneficial uses and users of groundwater and interconnected surface water. Design sustainable management criteria that reflect a 'Critically Overdrafted' subbasin designation by seeking to improve current groundwater conditions rather than allowing for continued aquifer depletions over the next two decades. For example, historical groundwater pumping has likelycontributed to stream disconnection illustrated in figure 2-66 (GSP 2-99); resulting in depleted stream flows and reduced baseflows in ESJ Subbasin tributaries, and exacert3ated high water temperatures in the lower San Joaquin River that negatively impact listed species such as the Chinook Salmon. Minimum thresholds and measurable objectives should reflect an effort to prevent further degradation to interconnected surface waters and to avoid undesirable results, rather than risk magnifying historical undesirable results through lowered groundwater elevations.

6. Comment #6 (Sustainable Management Criteria. 3.6 Degraded Water Quality, starting pp 3-10): The GSP wrongly abdicates responsibility for specific constituents by implying there is no nexus between specific groundwater contaminants and groundwater pumping (GSP pp 3-11).

Conserving California's WiCdCifeSince 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

a. Issue'. Tlie GSP identifies two primary water quality constituents of concern in the ESJ Subbasin: salinity and arsenic (GSP pp 2-76). The GSP only specifies sustainability management criteria for salinity. The GSP explains that other constituents, including arsenic, are managed through other regulatory programs, and suggests that because GSAs do not have land use authority, they lack an ability to manage for such constituents as arsenic (GSP pp 3-11). Science suggests that overpumping of aquifers can cause clay layers to compress and release dissolved arsenic, resulting in an increase of arsenic in extracted water ("Groundwater"). Thus, groundwater pumping actions can affect the presence, movement, and concentration of naturally occumng arsenic in groundwater, potentially increasing anthropjagenic and ecosystem exposure to arsenic contamination. According to SGIVIA statue, GSAs have the authorityto establish groundwaterjextractionallocations, among other relevant authorities [WC § 10726.4]. Because arsenic contamination can be impacted by groundwater pumping, and because GSAs have the authority to manage groundwater pumping, the ESJGA has a viable management lever over arsenic contamination in the ESJ Subbasin. b. Recommendation: Draft a plan to investigate the relationship between groundwater pumping and the presence, movement, and concentration of arsenic in the ESJ Subbasin and include the plan in the GSP submitted to DWR by January 2020. Develop sustainability criteria for arsenic accordingly and in partnership with existing jregulatory programs by the first 5-year GSP update due in January 2025.

7. Comment #7 (Monitoring Networks, starting pp 4-jl): Number and distribution of groundwater monitoring wells are insufficient for analysis. a. Issue: The cun-ent monitoring network lack^ a sufficient number and representative distribution of shallow groundwater monitoring wells to monitor impacts to environmental beneficial uses and users of groundwater and interconnected surface waters [23 CCR § 354.34(2)], Few wells are near interconnected surface waters or concentrations of ] GDEs; and therefore, there are fewdata points on shallow groundwater level trends. These data are critical to understanding groundwater management impacts on fish and wildlife beneficial uses and users of groundwater, including GDEs and interconnected surface water habitats, that are impacted disproportionately by shallow groundwater trends. b. Recommendation: Install additional shallowj groundwater monitoring wells near GDEs and interconnected surface waters, potentially pairing multipleConsetving Cafifomia's WiUCCife Since 1870 Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

completion wells with streamflow gauges for improved understanding of surface water-groundwater interconnectivity.

8. Comment #8 (Project and Management Actions; 6.1 Projects, Management Actions, and Adaptive Management Strategies: starting pp 6-1): Demand reduction management actions lack emphasis and specificity critical to ESJ Subbasin sustainability goal achievement.
a. Issue: The GSP project and management actions focus on supply augmentation, with only three projects intended to conserve groundwater through metering and systems optimization. Though the GSP reserves the flexibility to implement demand-side management In the future (GSP pp 6- 1), there are no specifics as to how the ESJGA would implement demand management. This lack of specificity on how demand will be managed may lead to deprioritization or delayed implementation of demand management actions, which can undermine a basin's ability to achieve sustainability goals. Considering the ESJ Subbasins' current unsustainable rate of groundwater consumption and considering the cost and timing challenges associated with supply augmentation projects, a balanced portfolio approach to achieve groundwater sustainability should Include demand-management strategies.
b. Recommendation: Add specific measures for initiating demand reduction on an earlier timeline in the ESJ Subbasin to account for groundwater pumping lag Impacts, supply-augmentation project implementation challenges, and a scaled ramping-down of groundwater use that is a necessary ingredient in San Joaquin Valley long-tenn groundwater sustainability. Be specific about triggers, timing, and expected outcomes of demand-management actions.

CONCLUSION
In conclusion, the ESJ Subbasin Draft GSP does not comply with all aspects of SGMA statutes and regulations. The Department deems the GSP insufficient In its consideration of fish and wildlife beneficial uses and users of groundwater and interconnected surface waters. The Department recommends that ESJGA address the above comments before GSP submission to DWR. If these comments are not integrated, the Department may recommend to DWR an 'incomplete' or 'inadequate' plan detemninatlon based on the following regulatory criteria for plan evaluations:

1. The assumptions, criteria, findings, and objectives, including the sustainability goal, undesirable results, minimum thresholds, measurable objectives, and interim milestones are not reasonable and/or not supported by the best available infonnation and best available science. [23 OCR § 355.4(b)(1)] (See Comment #2, 3, 4, 5, 7)
Conserving CaCifomia's WilifCifeSince 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority j
August 23, 2019

2. The GSP does not identify reasonable measures and schedules to eliminate data gaps. [23 CCR § 355.4(b)(2)] (See Comment #7)

3. The sustainable management criteria and projects and management actions are not commensurate with the level of understanding of the basin setting, based on the level of uncertainty, as reflected in the GSP. [23 CCR § 355.4(b)(3)] (See Comment #5, 6, 8)

4. The interests of the beneficial uses and users of groundwater in the basin, and the land uses and property interests potentially affected by the use of groundwater in the basin, have not been considered. [23 CCR § 355.4(b)(4)] (See Comment #1. 2, 3, 4, 5, 7)

5. The projects and management actions are not feasible and/or not likely to prevent undesirable results and ensure that the basin is operated within its sustainable yield. [23 CCR § 355.4(b)(5)] (See Comment #8)

6. The GSP does not include a reasonable assessment of overdraft conditions and/or does not include reasonable means to mitigate overdraft, if present. [23 CCR § 355.4(b)(6)] (See Comment #4, 8)
The Department appreciates the opportunity to provide comments on the ESJ Subbasin Draft GSP. Please contact Lauren Mulloy by email at [email protected] with any questions.

Sincerely,
Kevin Thomas
Regional Manager. North Central Region
Enclosures (Literature Cited)
ec: California Department of Fish and Wildlife
Joshua Grover, Branch Chief
Water Branch
[email protected]
Robert Holmes, Environmental Program Manager
Statewide Water Planning Program
Robert. [email protected]
Briana Seapy, Statewide SGMA Coordinator
Groundwater Program
[email protected]
Conserving C<^fifomia's M/ifxfCife Since 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

MaryLlsa Cornell, Water Unit Supervisor
North Central Region
[email protected]
Lauren Mulloy, Environmental Scientist
North Central Region
[email protected]
California Department of Water Resources
Craig Altare, Supervising Engineering Geologist
Sustainable Groundwater Management Program
[email protected]
Paul Wells, Eastern San Joaquin Subbasin SGMA Point of Contact North Central Region Office
[email protected]
National l\/1arine Fisheries Service
Rick Rogers, Fish Biologist
West Coast Region
[email protected]
Erin Strange, San Joaquin River Branch Lead
West Coast Region
[email protected]
State Water Resources Control Board
James Nachbaur, Director
Office of Research, Planning & Performance
[email protected]
Conserving CaCifomia's 'Pl/ilKCifeSince 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
Brandon Nakagawa, ESJ GSP Plan Manager
Eastern San Joaquin Groundwater Authority
August 23, 2019

Literature Cited
Barlow, P.M., and Leake, S.A., 2012, Streamflow depletion by wells—Understanding and managing the effects of groundwater pumping on streamflow: U.S. Geological Survey Circular 1376.

California Department of Water Resources: Community Water Center. "Critically Overdrafted Basins." or httDs://water.ca.Qov/Proarams/GroundwaterManaaement/Bulletin-118/Criticallv-Overdrafted-Basins Hallock, R.J., R.F. Elwell, D.H. Fry Jr. 1970. Migrations of adult king salmon Oncorhynchus tshawytscha in the San Joaquin Delta as demonstrated by the use of sonic tags. State of California. The Resources Agency. Department of Fish and Game.

Fish Bulletin 151.

Marston, D, C. Mesick, A. Hubbard, D. Stanton, S. Fortmann-Roe, 8. Tsao. T. Heyne. 2012. Delta flow factors influencing stray rate of escaping adult San Joaquin River fallrun Chinook salmon (Oncorhynchus tshawytscha). San Francisco Estuary & Watershed Science.

Naumburg E, Mata-Gonzalez R, Hunter R.G.. McLendon T, Martin D.W. 2005. Phreatophytic vegetation and groundwater fluctuations: a review of current research and application of ecosystem response modeling with an emphasis on great basin vegetation. Environmental Management. 35(6);726-40.

Stanford: School of Earth, Energy & Environmental Sciences. "Groundwater Quality in the Sustainable Groundwater Management Act (SGMA): Scientific Factsheet on Arsenic, Uranium, and Chromium." or
httDs://d3n8a8Dro7vhmx.cloudfront.net/communitvwatercenter/paaes/293/attachments/o riainal/1560371896/CWC FS Gmdv/trQual 06.03.19a.odf?1560371896 Conserving California's "WilxlTife Since 1870
Docusign Envelope ID: F80B7DB6-AC32-48E0-A681-47F69EA5EC01 ATTACHMENT 2
2 Mitchell Maidrand, P.E.

T2, D2
Deputy Director
Water Resources Division
Municipal Utilities Department
Delta Water Treatment Plant
11373 N. Lower Sacramento RD
Lodi, CA 95242
Phone: (209) 937-7353
Mobile: (916) 698-0293
From: Mitchell Maidrand <[email protected]> Sent: Tuesday, October 1, 2024 11:01 AM
To: Katie Cole <[email protected]>
Subject: RE: Draft GSP
Katie – I was reviewing the project tables in the GSP in the ES. For the City’s projects there should be some changes if possible. For the groundwater recharge project – under current status it should state: Basin design in progress, construction to begin in spring of 2025. Also recharge should be stated to be 20k AFY. Capital cost should be $11.5 M.

Under regulatory it should indicate CEQA required.

For the AMI – current status should indicate AMI project in progress. Capital costs should indicate $17 M. Also, since it is in progress shouldn’t we list it with the Category A projects?
If we can make these changes in this version of the GSP prior to submittal to DWR that would be great. Thanks.

C-1
C-2
ATTACHMENT 2
1 From: Bana Rousan-Gedese <[email protected]>
Sent: Monday, October 21, 2024 8:17 AM
To: [email protected] [PW] <[email protected]> Subject: ESJGWA GSP Public Comment
Hello,
I would like to submit public comment on behalf of the Eastside San Joaquin GSA. • In the Executive Summary, can Calaveras County be added to the description of the Eastside San Joaquin GSA in the second paragraph on page ES-1. It would then read as, "... Eastside San Joaquin GSA (Eastside GSA) (composed of Calaveras County Water District [CCWD], Calaveras County, Stanislaus County, and Rock Creek Water District)..." • In Chapter 1, page 1-7, also in the description of the Eastside GSA, please add Calaveras County so the first sentence is, "Eastside San Joaquin GSA (Eastside GSA) is a partnership between Calaveras County Water District, Calaveras County, Stanislaus County, and Rock Creek Water District."
Thank you!
Bana Rousan-Gedese
Water Resources Specialist
[email protected]
Office: (209) 754-3090
Cell: (209) 419-1474
You don't often get email from [email protected]. Learn why this is important ATTACHMENT 2
1 Emily Honn
From: Katie Cole
Sent: Thursday, October 31, 2024 4:53 PM
To: Emily Honn; Liz DaBramo
Subject: FW: Eastside GSA
From: [email protected] [PW] <[email protected]> Sent: Thursday, October 31, 2024 2:38 PM
To: Brandon Nakagawa <[email protected]>; Katie Cole <[email protected]> Subject: FW: Eastside GSA
From: Bana Rousan-Gedese <[email protected]>
Sent: Monday, October 7, 2024 12:16 PM
To: [email protected] [PW] <[email protected]> Subject: Eastside GSA
Hello,
I am writing to ask that the CCWD and Calaveras County descriptions on page 1-7 be modified to read as follows:

Calaveras County Water District: The Calaveras County Water District (CCWD) provides water service to approximately 13,360 municipal and residential customers in six service areas and shares the same boundaries as Calaveras County. Supply for CCWD comes from reservoir releases on the Calaveras, Stanislaus, and Mokelumne Rivers for a total of approximately 6,000 AF/year for primarily agricultural and residential use. CCWD has several customers with riparian rights along the Calaveras River, has one service area that relies solely on groundwater, and has several areas that utilize recycled water.

Calaveras County: Calaveras County has a total area of 1,037 square miles and extends beyond the boundaries of the Eastern San Joaquin Subbasin. Calaveras County Water District is the only public water supplier to residents located in the portion of the county overlying the Subbasin. The only incorporated city, Angels Camp, is located outside of the Subbasin. Calaveras County had one of the fastest growing annual percent increases in population in California between 2000 and 2010 (CCWD, 2020). For the portion of Calaveras County that falls within the Eastern San Joaquin Subbasin, there are numerous domestic, municipal, and monitoring wells.

Thank you,
Bana Rousan-Gedese
Water Resources Specialist
[email protected]
You don't often get email from [email protected]. Learn why this is important Office: (209) 754-3090
Cell: (209) 419-1474
ATTACHMENT 2
ATTACHMENT 2
1 From: Pat Dunn <[email protected]>
Sent: Tuesday, October 22, 2024 4:00 PM
To: Brandon Nakagawa <[email protected]>; [email protected]; [email protected] <IMCEAUNDEFINED-sesser+40condorearth+2Ecom@namprd16.prod.outlook.com> Cc: Bana Rousan-Gedese <[email protected]>; Jesse Hampton <[email protected]>; Suzanne Jarmusch <[email protected]>; Damon Wyckoff ([email protected]) <[email protected]> Subject: RE: Proposed Well Nest for Semi-annual Groundwater Quality Monitoring - 5921 Raindance Road Thanks Brandon:

Please note discrepancies between Tables 4-1 and 4-4 and Figure 4-5. CCWD wells are not referenced on the tables but are on the Figure.

Best Regards,
Pat Dunn, P.G., C.Hg.

NV5
Cell 916-221-0012
ATTACHMENT 2

To: Members of the Eastern San Joaquin Groundwater Authority and Members of the Groundwater Sustainability Agencies (via [email protected]) From: Mary Elizabeth M.S., R.E.H.S., Delta-Sierra Group Conservation Chair Date: 9.11.2024
Re: Eastern San Joaquin Groundwater Authority (ESJGWA) Steering Committee

9.11.2024 Comments
The ESJGWA adopted a well mitigation program and ordinance on August 14, 2024 and in the minutes of the meeting a final ordinance copy signed was not included only that there was an attachment to the agenda which was clearly indicated as draft. Please send out the final copy for all those that submitted comments on the document as a means of stakeholder engagement.

The implementation of this program is essential for the preparation for future drought conditions. Comments we submitted 4.10.2024 were not included in the minor revisions involving management, but those comments are still valid.

On March 6, 2024, the DWR
released Groundwater Well
Permitting Report -
Observations and Analysis of
Executive Orders N-7-22 and N3-23 which included San
Joaquin County in the top 10
counties with dry wells since
March 28, 2022 as shown
below.
1 These DWR dry well
data are reported voluntarily and
would not include reports by
individuals within a GSA.

Recent groundwater data has been uploaded to DWRs groundwater data system as shown below, current as of 9.7.2024, indicates that there are areas in our community that is vulnerable to groundwater lowering events, either from drought or from overdrafted groundwater extraction.
1 htps://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Groundwater-Management/Wells/Files/DWRWell-Permi�ng-Analysis-Final_March2024.pdf?utm_medium=email&utm_source=govdelivery ATTACHMENT 2

When investigating resources
linked to DWRs website I came
across the San Joaquin
Partnerships website which is
notable that specific San Joaquin
County resources were not listed
to provide residents with a local
contact while they are navigating
the problem that brought them to
the site.

I hope that the Groundwater
Authority adds their well mitigation
program to resources available to
San Joaquin County residents
residing within the Eastern San
Joaquin Subbasin.

Additionally, while not lead the
Eastern San Joaquin
Groundwater Authority has been
identified by guidance documents
to be a key player in the SB552
drought planning effort and as
such should be receiving regular
updates on plan development in
San Joaquin County to respond to
domestic well and small water systems water supply problems related to drought.

ATTACHMENT 2

As I was the only public member in attendance at the July 2024 meeting regarding the Stakeholder and Engagement Plan revision and the plan will not be released until the 5- year GSP update, stakeholder engagement is needed in a significant way. At that meeting there was acknowledgement that 5-year update will be heavily technical. The Groundwater Authorities insistence that the Technical Advisory Committee that regularly meets albeit on different topics all of which are current has created a deficient in the ability of residents to comprehend and provide comments on plans and reports that have a short 30 day comment period. Two substantial reports are under review concurrently.

We hope that instead of overview meetings that there be some public information meetings on the technical topics.

You may reach me at [email protected] if you have any questions or wish to discuss these issues in more detail.

Sincerely,
Mary Elizabeth M.S., R.E.H.S.

Delta-Sierra Group, Conservation Chair, Sierra Club
[email protected]
ATTACHMENT 2
Restore the Delta
2616 Pacific Ave #4296, Stockton, CA 95204
209-479-2053
www.restorethedelta.org
October 31, 2024
Eastern San Joaquin Groundwater Authority
1810 E Hazelton Ave
Stockton, CA 95205
Sent via email: [email protected]
Re: Eastern San Joaquin Groundwater Authority’s Draft Groundwater Sustainability Plan To Whom It May Concern:

Restore the Delta (RTD) works in the areas of public education, program and policy development, and outreach so that all Californians recognize the Sacramento-San Joaquin Delta as part of California’s natural heritage, deserving of restoration. We interface with local, state and federal agencies to advance this vision.

We envision the Sacramento-San Joaquin Delta as a place where a vibrant local economy, tourism, recreation, farming, wildlife, and fisheries thrive as a result of resident efforts to protect our waterways. We seek water quality protections for all communities, particularly environmental justice communities and California Tribes, as well as community protections from flood and drought impacts.

Ultimately, our goal is to connect communities to our regional rivers and to empower communities to become the guardians of the estuary through participation in government planning, community science and waterway monitoring, and a sustainable local economy. We seek to build the next generation of water leaders by developing programs in science, land and water management, and the green economy. Rooted in the Clean Water Act, we work for a Delta with waters that are fishable, swimmable, and drinkable, and farmable.

We envision improvements in the Delta as opportunities for Delta Tribes, Delta farming communities, and environmental justice communities to gain greater equity in decision making and to share in the benefits from area natural resources management.

We are providing comments on the Eastern San Joaquin Groundwater Authority’s (“Authority”) draft Groundwater Sustainability Plan (“Plan”), pursuant to a January 2025 deadline for submission to the Department of Water Resources. Groundwater management in the Eastern San Joaquin Groundwater Basin is of direct interest to our organization due to potential Delta and Delta-adjacent impacts in the watershed.

ATTACHMENT 2
Restore the Delta’s Comments on Eastern San Joaquin Groundwater Authority’s Draft Groundwater Sustainability Plan
2 We respectfully submit this letter for consideration in regard to the adoption of the amended Plan. After reviewing in detail, the amendments to the Plan, we have identified a number of flaws that the Authority should be aware of prior to the approval and adoption of the Plan.

Accordingly, we lay out our key concerns and findings, below.

SGMA background and RTD position on SGMA
After one of the most severe droughts in state history, former California Gov. Jerry Brown signed into law the Sustainable Groundwater Management Act (SGMA) in 2014 to ensure better local and regional management of groundwater use by 2040. SGMA was crafted to shift traditional views of groundwater use away from the current siloed approach to encourage cities, counties, and irrigation districts to work together in a regional collaborative process.

SGMA requires over-drafted water basins to become sustainable (prevent overdrafts from pumping more than what is replenished during the year) by 2040. Over-drafting means more water is pumped from a groundwater basin than is replaced through sources like rainfall, irrigation water, streams fed by mountain runoff, and intentional recharge efforts (spreading surface water to feed into the basin).

The 70-square-mile Eastern San Joaquin Groundwater Subbasin is bounded by the Sierra Nevada foothills to the east, San Joaquin River to the west, Dry Creek to the north, and the Stanislaus River to the south. It’s one of 21 basins and subbasins identified by the California Department of Water Resources (DWR) as being in a state of critical overdraft. Current analysis indicates that groundwater pumping offsets and/or recharge on the order of 95,000 acre-feet per year (AF/year) may be required to achieve sustainability.

Local stakeholders had until 2022 (in critically overdrafted basins until 2020) to develop, prepare, and begin implementation of Groundwater Sustainability Plans (GSP). The first reports of an area's effort toward sustainability were filed in 2020 and the first 5-year updates are required by January 2025. Plans include various projects and management actions that are supposed to help the basin reach a balance between inputs (rivers, rainfall, etc.) and outputs (pumping for irrigation, drinking water, etc.).

Summary of concerns
With public trust requirements of SGMA, the Authority has legal and fiduciary responsibilities for proper implementation of the Ground Water Sustainability Plan. We are concerned that the Authority has failed to follow State mandates. First, the compliance issues in regard to funding accountability put the entire subbasin at risk of sanctions and further punitive actions by the State. Second, fundamental stakeholder engagement is required by law and must be a part of the process through better community outreach, Tribal engagement, disadvantaged community inclusion, and small farmer protections. Additionally, the Plan the Authority is reviewing does ATTACHMENT 2
Restore the Delta’s Comments on Eastern San Joaquin Groundwater Authority’s Draft Groundwater Sustainability Plan
3 not identify current permit applications for carbons sequestration projects that could affect the subbasin particularly, through CO2 sequestration. Poor planning for the future will, therefore, leave the Authority and its member agencies ill-prepared for future monitoring. Listed below are the flaws we have found in the current iteration of the Plan that will then be discussed in greater detail in descriptive narrative.

1. Three Groundwater Sustainability Agencies have failed to develop groundwater sustainability proposals and must be brought into compliance to avoid state sanctions for the entire Subbasin. This process requirement should have been completed over the course of the last three years and ready for public review now.

2. San Joaquin County is diverting funding that is supposed to be used for local flood control and water management projects to pay for Authority fees.

3. The Authority needs to significantly improve its communications and community engagement methods to ensure the vast array of perspectives across the Subbasin are meaningfully incorporated into regional groundwater sustainability planning efforts.

4. None of the 43 groundwater sustainability projects listed in the draft plan are located in South Stockton, a historically disadvantaged community that requires investment in groundwater protections.

5. The plan should be amended to include protections for small farmers.

6. The plan does not adequately identify or address subsidence.

7. The plan needs to explicitly address future monitoring plans for geologic CO2 sequestration site proposals in the Subbasin, and ensure local groundwater monitoring programs are well-integrated into existing public monitoring networks.

8. At public meetings, and in the documents, sustainability has not been fully and adequately defined, and does not encompass a broad definition of sustainability that represents the public interest.

Below are detailed sections regarding our concerns with the draft plan:

1. The three GSAs that have failed to develop groundwater sustainability proposals must be brought into compliance to avoid state sanctions for the entire Subbasin.

The lack of participation of three GSAs, including San Joaquin County, could cause all GSAs in the Subbasin to be subject to penalties from the State Water Board.

These would not only impact farmers but also property owners in the cities and urban areas of San Joaquin County.

The Eastern San Joaquin Groundwater Authority (“Authority”) is a joint powers agency consisting of 16 Groundwater Sustainability Agencies (GSAs) that make up the Eastern San Joaquin Subbasin. The purpose is to coordinate the various GSAs’ management of the basin, in accordance with SGMA. The updated Groundwater Sustainability Plan that the Authority and member GSAs were charged to submit to the state is supposed to show progress toward G-1
ATTACHMENT 2
Restore the Delta’s Comments on Eastern San Joaquin Groundwater Authority’s Draft Groundwater Sustainability Plan
4 groundwater sustainability by 2040. GSAs that have had their GSPs found to be deficient have been subject to enforcement (probation) by the State Water Board. For the GSAs in Kings County, for instance, this has meant the imposition of fees on wells and a fee per acre foot of water pump (the implementation of this has been stayed temporarily by the court). Additional fees will impact small farmers and economically disadvantaged households situated in the County and dependent on groundwater wells.

The three GSAs without plans are (1) San Joaquin County, (2) Central San Joaquin Water Conservation District, and (3) a Stanislaus County GSA in the southeast corner of San Joaquin/Stanislaus County. These GSAs have made no progress and have no proposals in place to work towards groundwater sustainability.

The failure of these three GSAs to develop their plans as stated above, could lead to sanctions by the State Water Board on all GSAs in the Subbasin, including per well charges along with additional charges per acre foot pumped. In the current agricultural economy such a charge would not be Sustainable and could potentially put small farmers out of business, create unemployment, reduce purchases of agricultural inputs, lower tax revenues, and subsequently property values.

2. Because the San Joaquin County Board of Supervisors has diverted over $800,000 that was meant to be used for local flood control and water management projects to pay for Authority fees, most property owners are paying twice to meet SGMA requirements.

Groundwater Sustainability Agencies (GSAs) share in the general operating and administrative cost of operating the Authority in accordance with percentages determined by the Authority Board of Directors. GSAs are solely responsible for raising funds for payment of their individual shares. The current scheme of shifting public funding designated for flood control to pay for San Joaquin County’s GSA is double taxation, and by shortchanging flood control spending puts County residents at risk physically and financially from a flood incident.

San Joaquin County’s GSA is comprised of unincorporated areas of San Joaquin County and the Tracy Basin. Specifically, San Joaquin County is paying its GSA fees with monies from Flood Control and Water Conservation District Zone 2, an investigation zone with the primary purpose of carrying out engineering, geologic, and other studies including the reclamation, storage, distribution, purchase, sale, use, conservation, and development of water including the management of combined surface water and groundwater supplies. Zone 2 gets its funding from agricultural landowners on a per acre charge of $.48 per acre plus a parcel charge of $.768, along with various other charges collected on beneficial properties.

More than 62% of the Zone 2 District’s annual budget – $1,358,000 – is being diverted for Authority fees. Zone 2 money (according to the Zone 2 website) is being used to pay for the G-1
con't
G-2
ATTACHMENT 2
Restore the Delta’s Comments on Eastern San Joaquin Groundwater Authority’s Draft Groundwater Sustainability Plan
5 eastern subbasin monitoring ($138,000), GWA fee ($25,000), a GSP/SGMA consultant ($25,000), and an additional contribution to the ESJ GWA ($225,000) for a total of $413,800 for the Eastern Subbasin. Payment for the Tracy subbasin adds another $231,267 for a total of $802,840 from Zone 2.

The reason given for not assessing fees on the areas encompassed in the San Joaquin County GSA is that the Board of Supervisors did not want to address issues associated with the implementation of Proposition 218 or engage in establishing a “beneficial” district that would be subject to fees. The consequence is that others are being required to subsidize the San Joaquin GSA with their Zone 2 payments and still paying Authority assessments through the charges from their respective GSA, which is effectively double taxation. This is an equity concern for disadvantaged households and an economic hardship for small farming businesses.

3. The Authority needs to significantly improve its communications and community engagement methods to ensure proper stakeholder engagement and that the vast array of perspectives across the Subbasin are meaningfully incorporated into regional sustainability planning efforts.

It’s been over a year since the 2023-2024 Civil Grand Jury published a scathing review of the Authority’s planning activities. Many of the issues raised by the Grand Jury, including a lack of transparency and inequitable community engagement practices, remain unresolved. Jurors recommended a variety of measures to the Authority for improving accessibility and transparency (e.g. updating its website with meeting times, agendas, and minutes; disclosing financial and project information, etc.), and diversifying community engagement.

Despite these recommendations, meaningful stakeholder and community engagement efforts have remained insufficient, especially in communities like Stockton, the largest city in the subbasin and broader Sacramento-San Joaquin Delta region, which has the highest proportion of environmental justice (EJ) communities in California. Overall, nearly 30% of the Delta's population belongs to EJ communities that are disproportionately impacted by the degradation of Delta waterways. This environmental degradation affects their health, well-being, and economic opportunities.

The Authority has failed to proactively engage with Tribal Nations and Disadvantaged communities from the inception of the agency and throughout ongoing development of the overarching Groundwater Sustainability Plan for the subbasin. Both are listed as proper stakeholders in the Plan and SGMA regulations. The Plan has been in development for three years, yet meaningful outreach and community involvement only began in the final four months.

This last-minute effort to engage EJ communities is unacceptable. The absence of consistent engagement from the project's onset failed to prioritize the voices and concerns of those most impacted, reinforcing a long-standing pattern of exclusion. Three meetings were originally planned, but at the most recent public meeting, when community members asked budget-related G-3
ATTACHMENT 2
Restore the Delta’s Comments on Eastern San Joaquin Groundwater Authority’s Draft Groundwater Sustainability Plan
6 questions, they were directed to speak with county representatives privately rather than having an open discussion.

Similarly, the Authority has done little to address accessibility issues for engaging in plan development. The requirement for public comments to be submitted in writing, for instance, creates challenges for community members who lack access to the internet and computer literacy and removes a layer of transparency between communities.

Lackluster engagement and inaccessibility issues add to the history of limited public events and outreach, especially concerning the Eastern San Joaquin GSP, highlighting a systemic issue:
critical EJ communities were not adequately consulted and lack of stakeholder outreach. Waiting until the final phase of a three-year process to involve these communities undermines the potential for equitable outcomes. Participation from the beginning would have advanced shared concerns while shaping groundwater sustainability planning efforts in ways that protect health and livelihood. Going forward, the Authority must adopt a more inclusive and transparent approach to ensure these communities have a meaningful role in water management decisions.

One of the Grand Jury’s recommendations was for the Authority to “identify ways to better find and engage with members of disadvantaged communities (DACs), including non‐English speakers, in the San Joaquin Subbasin.” The Authority responded that it would consider ways to expand language access in its pending “Communications and Engagement Plan”, which was to be posted within 10 days after its adoption (GJR, p. 183). As of writing, this plan has not been made publicly available.

To support the 5-year Periodic Evaluation of the GSP and development of the 2024 GSP Amendment, the Authority’s Steering Committee approved the formation of a Project Management Committee (PMC), “comprising six GSA volunteers representing the varied interests in the Subbasin and covering both urban and agricultural areas” who met 20 times on a bi-monthly basis. The “20 meetings” described in the draft plan were not publicly accessible.

Further, against the recommendation of the Grand Jury, the Authority Board of Directors refused to amend its bylaws and update its website to reflect the actual meeting times of the Board. The Authority’s reasoning for its lack of transparency was that board meeting frequency is variable.

The Authority also refused to formalize the status of its Technical Advisory Committee as a standing committee and bring it into compliance with the requirements of the Ralph M. Brown Act. These actions show an unwillingness to integrate more diverse perspectives into the Authority’s planning processes.

4. None of the 43 groundwater sustainability projects listed in the draft plan are specifically designated to benefit South Stockton. A historically disadvantaged community that requires investments in groundwater protections (e.g. water recycling, stormwater reuse, aquifer recharge, etc.).

G-4
ATTACHMENT 2
Restore the Delta’s Comments on Eastern San Joaquin Groundwater Authority’s Draft Groundwater Sustainability Plan
7 The GSAs have identified 43 projects for potential development that either replace groundwater use (offset) or supplement groundwater supplies (recharge) to meet current and future water demands. Project types include direct and in-lieu recharge, intra-basin water transfers, demand conservation, water recycling, and stormwater reuse. Furthermore, the Authority failed to hold the City of Stockton accountable for not analyzing groundwater conditions thoroughly in South Stockton in order to meet environmental justice needs for this historically redlined community.

On the heels of three years of lackluster engagement with disadvantaged communities and Tribes, the list of proposed beneficial projects in the plan is, unsurprisingly, largely concentrated away from communities who have historically been harmed the most by inequitable water and land management planning. This represents a missed opportunity for project development at the intersection of groundwater recharge and floodplain restoration in San Joaquin County that could’ve been highly competitive for federal and state funding if environmental justice considerations had been prioritized in the initial scoping phase.

Going forward, we request that the Authority encourage member GSAs to emphasize how their proposed projects can advance environmental justice and offer meaningful community benefits, including unincorporated areas of East Stockton that fall in the County. Ideally, projects should be co-designed from the start with community-based organizations who are experts on local environmental and public health challenges. Enhancement of projects and methodology can only be accomplished with more equitable community engagement practices.

5. The plan needs to be amended to explicitly outline protections for small farmers.

In 2023, the California Legislature passed AB 779, which sets new terms for comprehensive adjudication of groundwater rights in civil court. This SGMA add-on became effective this year.

It asks courts to consider the “water use of small farmers and disadvantaged communities,” in SGMA-related decisions (for the purposes of the bill, small farmers are those who earn between $10,000 and $400,000 in gross income). Several areas in need of revision include subsidence and small farm protections from substantial fees and undue burdens.

Subsidence leads to undesirable results on farmland. Dr. Steven Deveral from Hydro Focus based out of Davis, CA points out in his Simulation of Subsidence Mitigation Effects on Island Drain Flow, Seepage, and Organic Carbon Loads on Subsided Islands Sacramento–San Joaquin Delta how subsidence is affected by groundwater pumping (Deveral, 2017). We recommend looking over this study and making sure to consider his findings when setting up a subsidence baseline to be in compliance with AB 779.

The Authority must ensure small farmers and disadvantaged communities are protected.

Disproportionately burdening small farmers with fees, further meetings, and administrative processes that will have negative impacts on their small farms is a further failure of the public G-5
G-5
G-5
ATTACHMENT 2
Restore the Delta’s Comments on Eastern San Joaquin Groundwater Authority’s Draft Groundwater Sustainability Plan
8 trust responsibility of the Authority. With over three hundred thousand acres of agricultural land in the subbasin consideration for this stakeholder group must be research and addressed to provide proper protections for small farmers.

6. The plan needs to explicitly address future monitoring of potential groundwater contamination risks associated with geologic CO2 sequestration site proposals in the subbasin and ensure local groundwater monitoring programs are well-integrated into existing public monitoring networks.

The Plan lacks a section reviewing emerging industries and the potential for impacts to groundwater. Successful implementation of CO2 sequestration projects proposed in the western part of the subbasin demands careful coordination between project operators and groundwater protection efforts. To facilitate redundancy and data-sharing, extensive groundwater monitoring systems required under US EPA Class VI Underground Injection Control permits should be integrated into the existing subbasin monitoring network. Additionally, the results should be made publicly available.

The current sustainability indicators and minimum thresholds in the draft plan should be expanded to include monitoring for CO2-related impacts, including changes in groundwater acidity, pressure gradients, and water quality parameters. Regular testing for acidity levels near injection sites should be integrated into the GSP’s measurable objectives with clear guidelines for corrective action if monitoring reveals potential impacts to groundwater quality and quantity.

These protections are essential to prevent undesirable results and ensure the long-term viability of the region’s groundwater resources.

7. As full analysis and plans have not been completed for all GSAs, environmental justice needs and concerns have not been addressed or incorporated into basin projects, subsidence is not being accurately addressed, and misuse of public funds continue with San Joaquin County GSA operations, the plan fails to adequately define or demonstrate sustainability as required under the law.

Conclusion
In summation, Restore the Delta has reviewed the Eastern San Joaquin Groundwater Authority’s draft Groundwater Sustainability Plan and found the document with its efforts to be lacking critical components. The failure of three GSAs to develop groundwater plan, and the Authority’s failure to ensure that San Joaquin County’s GSA properly allocates funds place the entire subbasin at risk of sanctions. The minimal engagement of stakeholders by the Authority does not meet environmental justice requirements for SGMA as required by law, or meet the standards for public trust responsibilities of proper outreach, collaboration, and good neighbor efforts. There are no disadvantaged community projects in the County’s most pollution burdened areas, and a lack of protections for small farmers. Finally, future planning for emerging industry coordination G-6
G-6
G-6
ATTACHMENT 2
Restore the Delta’s Comments on Eastern San Joaquin Groundwater Authority’s Draft Groundwater Sustainability Plan
9 must be added to the Plan and the Authority’s goals. Collectively, this Plan falls short of DWR requirements and the intentions of the purpose of state and local agency efforts. These cumulative flaws make the amendment incomplete and not to standards set by SGMA. Restore the Delta recommends deep consideration of these issues prior to submitting this plan to DWR for Subbasin certification.

Respectfully Submitted,
Michael Machado Barbara Barrigan-Parrilla
President Executive Director
Restore the Delta Restore the Delta
Ivan Senock Sara Medina
Deputy Director Sustainable Agriculture Program Manager Davis Harper
Carbon and Energy Program Manager
ATTACHMENT 2

10.31.2024
Eastern San Joaquin Groundwater Authority Board
Members of the GSAs in the Eastern San Joaquin Subbasin P. O. Box 1810, Stockton, CA 95201
via [email protected]
Re: Draft Eastern San Joaquin Groundwater Sustainability Plan Amendment (2024) The Delta-Sierra Group of the Mother Lode Chapter, of the Sierra Club has over 600 members throughout San Joaquin County which includes a large portion within the Eastern San Joaquin Subbasin as shown below. The Mother Lode Chapter includes all areas within the Eastern San Joaquin Subbasin including San Joaquin County, Calaveras County and Stanislaus County. Due to the length of the Draft Eastern San Joaquin Groundwater Sustainability Plan Amendment (Draft 2024 GSP Amendment) and short review time, our comments will primarily relate to stakeholder engagement, a problem that continues affecting the ability of stakeholders to meaningfully engage in the development and implementation of the groundwater sustainability plan (GSP).

Stakeholder Engagement
The Delta-Sierra Group (DSG) has written numerous letters regarding the availability of the draft 5-year update of the 2020 GSP and revised 2022 GSP, ad hoc technical meeting transparency, and information availability on the Eastern San Joaquin Groundwater Authority (ESJGWA) website, www.esjgroundwater.org, since the 2022 GSP update in response to the Department of Water Resources (DWR) determination that the 2020 GSP ATTACHMENT 2

was deemed incomplete. These DSG correspondence submittals have also been posted on the DWR SGMA Portal. The 2022-2023 San Joaquin Grand Jury reported on several issues related to monetary and information transparency which was published June 2023.

While some improvements have been made, a sustained effort and systemic changes to stakeholder engagement have not occurred and continues to plague the ability of stakeholders to meaningfully engage in the development and implementation of the GSP.

For example, two rounds of DWR facilitation grants for the purpose of developing an updated stakeholder communication and engagement plan have not yielded a public plan.

These DWR facilitation providers assist GSAs all over the state and why a draft communication and engagement plan has not been made available in the Eastern San Joaquin Subbasin is perplexing. The ESJGWA will spend over 1 million dollars, including Zone 2 Groundwater Investigation property assessment dollars for this GSP Amendment, primarily developed, without public input. The water managers of the groundwater sustainability agencies (GSAs) have known and been working on the overdrafted aquifer for many years with limited public involvement, yet groundwater overdrafts persist. The Sustainable Groundwater Management Act (SGMA) adopted 10 years ago is the State of California’s answer to persistent groundwater over pumping in critically overdrafted basins in our state, like the Eastern San Joaquin Subbasin. Since the State of California adopted the SGMA, progress has been made to increase data availability and guidance has been developed to help local water agencies move towards sustainability. Many years will be needed to achieve sustainability that responds to water use changes and hydrologic changes relating to climate change, while continuing efforts to maximize groundwater use.

A well mitigation program, not yet implemented, and a demand management strategy are included in the Draft 2024 GSP Amendment with the expectation that wells will continue to go dry as the maximum groundwater use is determined until sustainable conditions are achieved.

The Draft 2024 GSP Amendment was released October 1, 2024 with a 30 day comment period consisting of fifteen documents as shown below which had not been released previously for public stakeholder review.
1 ▪ Notice of Intent to Adopt an Amended Groundwater Sustainability Plan ▪ Executive Summary (Public Draft)
▪ Chapter 1 Agency Information, Plan Area, and Communication (Public Draft) ▪ Chapter 2 Basin Setting (Public Draft)
▪ Chapter 3 Sustainable Management Criteria (Public Draft) ▪ Chapter 4 Monitoring Networks (Public Draft)
▪ Chapter 5 Data Management System (Public Draft)
▪ Chapter 6 Projects and Management Actions (Public Draft) ▪ Chapter 7 Plan Implementation (Public Draft)
▪ Chapter 8 References (Public Draft)
▪ Appendices (Public Draft)
▪ Chapter 1
▪ Chapter 2
▪ Chapter 3
▪ Chapter 5
▪ Chapter 6
1 https://www.esjgroundwater.org/Documents/GSP
ATTACHMENT 2

When combined these Draft 2024 GSP Amendment documents comprise 1602 pages with an unreasonable expectation that stakeholders are going to be able to review and engage in the development of the plan with a 30 day comment period. This is disappointing and not surprising despite correspondence requests in January 2024 for a 90 day public review comment period that was included in the December 2023 ESJ 2025 GSP Update Scope of Work.
2 The Notice of Intent to Adopt an Amended Groundwater Sustainability Plan released 7.24.2024 clarified this 90 day review period and included the following statement which illustrates the restriction of information preventing all stakeholders from participating in the development of the Draft 2024 GSP Amendment.
3 Cities or counties that receive this notice may request in writing to consult on the proposed amended GSP. Please submit any such requests to the undersigned using the contact information below within thirty (30) calendar days of receipt of this notice.

The general public, groundwater users, domestic well owners, and small water systems which are vulnerable to groundwater overdraft due to excessive groundwater extraction for various uses, primarily agriculture, were not invited to participate in consultation meetings while the Draft 2024 GSP Amendment was developed. The three 2024 workshops: well mitigation program, communication and engagement plan development, and GSP amendment overview, were held in the late afternoon-early evening and were the first outreach meetings since 2019,before a final report was submitted to DWR. ESJGWA meetings are not forums for discussions between groundwater users and plan managers.

The notion that public meetings of ESJGWA provided adequate information to make meaningful comments is not evidenced especially when presentations are not made available in advance of the meeting or in some cases following the meeting. The general public including groundwater users are seeing the report contents for the first time between

10.1.2024 and until 10.31.2024. The Sierra Club will be submitting additional comments to DWR for their consideration while reviewing the Final 2024 GSP Amendment as more than 30 days are needed to review technical aspects contained therein.

The adopted stakeholder communication and engagement plan from the 2020 GSP was not implemented after the 2020 GSP submittal to DWR. The San Joaquin 2022-2023 Grand Jury requested that by 11.1.2023 the ESJGWA develop specific methods to engage with disadvantaged communities and communication with non-English speaking groups. The ESJGWA stated in its 9.23.2023 response that a community and engagement plan was under development using a Department of Water Resources facilitation grant. A draft of this plan has not been released to the public and scant information was presented at the second 2024 outreach meeting since 2019 whose purpose was to present the communication plan and which was attended by one member of the public not affiliated with a Groundwater Sustainability Agency (GSA). Furthermore, the ESJGWA issued correspondence dated

9.11.2024 stating that a communication and engagement plan recommended by the 2023- 2024 San Joaquin County Grand Jury will be adopted on 12.11.2024 by the ESJGWA.4 This communication and engagement plan which is referenced in the Draft 2024 GSP Amendment is absent with only a placeholder, Appendix 1-H. No draft communication and 2 ESJ 2025 GSP Update Scope of Work December 2023 link
3 Notice of Intent to Adopt July 2024 link
4 2024 ESJGWA Response submitted regarding the 2023-204 San Joaquin County Grand Jury Report link ATTACHMENT 2

engagement plan is available for public review. Without adequate public availability of information, as issues are considered, stakeholders without access to relevant information cannot meaningfully participate in the development or implementation of the adopted GSP.

The third 2024 outreach meeting since 2019 occurred on 9.25.2024 before the release of the Draft 2024 GSP Amendment and included an informative presentation slide deck which as of 10.28.2024 was not posted on the outreach page.5 Since the third outreach meeting was for the purpose of engaging with interested stakeholders and not an agendized meeting of the governing body of the ESJWGA, the fact that material presented was not posted would not be a violation of California Government Code Title 5, Division 2, Part 1 Powers and Duties Common to Cities, Counties, and Other Agencies, Section 54957.5.

Violations of this provision of not posting meeting materials in advance of the meeting or immediately after so that members of public can participate, is business as usual, in the Eastern San Joaquin Subbasin and records of how this practice inhibits participation has been documented in comments submitted at various times since before the first GSP was submitted in 2020. For example, the material presented at the 9.11.2024 ESJGWA meeting is still not posted nor are the approved 2024 meeting minutes after 3.13.2024 posted on the website.6 Minutes posting was a practice which the ESJGWA agreed to do in response to the 2022-2023 San Joaquin Grand Jury Report on the ESJGWA policies and practices. 7 2018 Groundwater Sustainability Workgroup Meetings Legacy During the development of the initial GSP submitted to DWR in January 2020, a facilitation grant was obtained from DWR for the purpose of outreach and included the Stakeholder Workgroup which met after normal work hours on a monthly basis to review and discuss topics considered during the GSP development. Without a formal vote by the ESJGWA Board, no further meetings were held even though the adopted outreach plan was included in the GSP submitted to DWR both in 2020 and 2022. The last meeting with a record on the ESJGWA website was June 2019. No subsequent meetings on a quarterly/annual basis to discuss GSP implementation and reporting occurred. The Draft 2024 GSP Amendment continues to reference this outreach effort from five years ago and while it was a good example of outreach, the outreach ended five years ago without a replacement. The Draft 2024 GSP Amendment stated “The Workgroup included members from a variety of organizations who represent one or more of the interested parties’ groups. Table 1-4 lists the organizations and interests represented on the Workgroup. While this Workgroup was not active during the 2024 GSP amendment process, the information collected during their involvement remains relevant and a guiding factor in this update and GSP implementation.” (emphasis added)
The Final 2024 GSP Amendment should include a summary of the referenced information that was deemed relevant from June 2018- August 2019 that was relied upon during the development of the Draft 2024 GSP Amendment. Include an explanation of how the Workgroup would have guided the restriction of draft information availability during this update when the Workgroup was able to review draft chapters during their review process. 5 Five-Year GSP Update and Amendment Meeting and Outreach webpage as of 10.28.2024 6 ESJGWA Meeting Agenda webpage as of 10.28.2024
7 2023 ESJGWA Response submitted regarding the 2022-2024 San Joaquin County Grand Jury Report link ATTACHMENT 2

Finally, as many conditions have changed since 2019, how has the stakeholder workgroup thoughts from more than five years ago relevantly guided GSP implementation? “The original goals of the 2018 Outreach and Engagement Plan are still relevant in the recent iterations of this plan”. The 2018 plan is the only adopted public plan though never it was never fully implemented despite these bulleted statements:
• Keep an interested list of stakeholders informed and aware of opportunities for involvement through email communications and/or their preferred mode of communication.

On multiple occasions the DSG has requested that meetings that have a zoom/teams videoconferencing component be recorded for stakeholders that are unable to attend daytime meetings to view the meeting contents and discussions at a preferred time.

Please include in the Final 2024 GSP Amendment how meeting recordings will be incorporated into stakeholder communications.
• Engage DWR for facilitated support to aid in the development of the GSP Multiple emails were sent to the current DWR facilitation support staff which were not returned. Please provide clear directions to stakeholders about communication expectations between ESJGWA staff and the public in the Final 2024 GSP Amendment. • Open ESJGWA planning efforts to the public with agendas and meeting minutes published on the ESJGWA website
Minutes are not separately published after approval nor are presentations included with the agenda posting so that stakeholders unable to attend the meeting can submit relevant comments for consideration prior to ESJGWA Board/Steering Committee actions. The Final 2024 GSP Amendment should include a discussion about how open meetings can be facilitated when meeting materials are not posted in advance of the meeting. • Inform and obtain comments from the general public through public meetings held on an approximately quarterly basis
There are no regular evening meetings either quarterly nor annually in coordination with the submittal of the annual report to inform and obtain comments other than at the ESJGWA Board or Steering Committee meetings that are infrequently held and often cancelled as evidenced in the meeting website record referenced previously. ESJGWA Board of Directors or Steering Committee meetings are very rarely held for purposes of a workshop. • Facilitate productive dialogue among participants at Advisory Committee, Workgroup, and public meetings
A dialogue regarding information availability and public attendance at ad hoc technical advisory committee (ad hoc project management committee) began on 9.11.2024 during an ESJGWA meeting, then staff counsel interrupted the dialogue resulting in the acting chair of the meeting to remind staff counsel of the ability of ESJGWA Board members to ask questions. Again, this dialogue, albeit limited, occurred at the prerogative of a ESJGWA Board member, and was not recorded. The Final 2024 GSP Amendment must include the methodology by which these productive dialogues will be facilitated and the means by which recordings will be made available for stakeholders unable to attend live meetings.

ATTACHMENT 2

• Provide timely and accurate public reporting of planning milestones through the distribution of outreach materials and posting of materials on the ESJGWA website for the GSP.

Draft annual reports are not available to review before adoption by the ESJGWA. The Final 2024 GSP Amendment should describe the public review processes of various planning milestones that will occur at intervals throughout the implementation of the GSP and which are reviewed during the annual plan development process.

The California Department of Water Resources (DWR) released in October 2023 a report, “A Guide to Annual Reports, Periodic Evaluations, & Plan Amendments”, which provides guidance when developing required reports.8 This guidance document includes some consideration about when an amendment is to be prepared one of which is “a GSA may determine to amend a Plan to incorporate changes or additions that are desirable or necessary to comply with public disclosure and stakeholder engagement requirements or policies.”
The possibility exists that some of these communication and engagement issues may be related to lack of knowledge and understanding rather than a deliberate disregard to the SGMA outreach requirements and good governance.
9 As the implementing agency for the
GSP, the ESJGWA cannot hide behind the SGMA language that the GSAs are the primary agency responsible for outreach as was mentioned several times in responses to the 2022- 2023 San Joaquin County Grand Jury report. This is not to say that all GSAs are not doing some outreach communications and providing opportunities to engage. However, the GSA with the largest population of residents, some of which pay the highest fees for water, the City of Stockton GSA, do not hold regular meetings to discuss the GSP implementation and monitoring. The City of Stockton held a very rare meeting on 10.2.2024 (one day after the public Draft 2024 GSP Amendment release date) of their Water Advisory Group to recommend that the City Council Water Committee consider adoption of the 2024 GSP Amendment. Then the City Council Water Committee on 10.10.2024 approved the motion 2024-10-10-0302 adopting the GSP and authorizing the ESJGWA to submit the GSP to the DWR before even a final report was prepared. 10
Perhaps, DWR would be willing to present to the GWA and all GSA members information contained in their guidance documents regarding stakeholder outreach to ensure that stakeholders can meaningfully engage in the development and implementation of groundwater sustainability plans.
• Maintain an active communications tracking tool to capture stakeholder engagement and public outreach activities and to demonstrate the reporting of GSP outreach 8 https://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Groundwater-Management/SustainableGroundwater-Management/Best-Management-Practices-and-Guidance-Documents/Files/GSP-ImplementationGuidance-Report.pdf 9 https://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Groundwater-Management/Assistance-andEngagement/Files/Guidance-Doc-for-GSP---Stakeholder-Communication-and-Engagement.pdf 10 Draft Minutes 10.10.2024 accessed 10.31.2024
https://stockton.granicus.com/GeneratedAgendaViewer.php?view_id=58&clip_id=8824 ATTACHMENT 2

activities through the use of qualified facilitators to obtain, consider, and integrate feedback accordingly throughout the planning process.

Note in October 2023, the DSG discovered that not only are there never any responses to correspondence that we submit but that the “official email address” for the GWA was not being monitored and that was the email that all SGMA Portal comments were then being sent. Additionally, comments that were addressed to ESJGWA and all GSA members may not be distributed to all GSA members as a California Public Records Act request to a GSA did not yielded after 21 days, a letter which we submitted to the ESJGWA addressed to all GSA members on 9.11.2024.
11 Ad Hoc Committees and Public Information
All of the discussions of drafts throughout the plan amendment development process were not public, instead utilizing an ad hoc project management committee formed by the ESJGWA Board of Directors Chair. According to the ESJGWA these technical ad hoc committee meetings do not have to be open to the public because the ad hoc committee are formed for specific purposes and for a limited amount of time.

The ESJGWA ad hoc project management committee formed in December 2023 included six GSA staff representing agricultural and urban interest which met bi-monthly for an unspecified amount of time. This ad hoc project management committee not only reviewed and guided the GSP amendment development process but was also tasked with coordinating other SGMA implementation efforts including the development of a well mitigation program, coordinating stakeholder outreach and engagement, and annual and long-term budgeting, reviewing draft work products and other meeting materials. These meeting materials and draft work products were never made public to allow stakeholders the same access to information on a regular basis throughout the development process.

The ESJGWA ad hoc project management committee that did not hold open meetings was also responsible for recognizing and flagging items requiring discussion and directions from “stakeholders”, the ESJGWA Steering Committee and Board of Directors. This ad hoc project management committee seems to have a considerably greater focus than a reasonable person would describe as a narrow focus and meetings should have been public. No disclosure of the “stakeholders” that were involved in these discussions or were any of the recommended directions that these “stakeholders” provided was disclosed in the Draft 2024 GSP Amendment. During the 9.11.2024 ESJGWA meeting there was expressed a desire for this group to continue beyond the plan amendment period.

The ad hoc project management committee membership was disclosed in the ESJWRM Version 3.0 Model Update dated October 2024 that was included as part of the Draft 2024 GSP Amendment. These six individuals were consulted during meetings closed to the public regarding the model update on which many decisions regarding the condition of the subbasin are based. Additionally, individual GSAs were not consulted directly during this Eastern San Joaquin Water Resources Model (model) update. Whether or not GSA staff, not members of the ad hoc project management committee, were allowed to listen in on these model development and refinement meetings was not specifically disclosed. The 11 CA PRA Information not found
ATTACHMENT 2

importance of the model refinement and assumptions cannot be stressed enough because the model is the basis for decision making and determining when sustainability is achieved:
▪ Developing understanding of Subbasin inflows, outflows, and change in storage under variety of conditions and planning horizons (historical, current, future) ▪ Understanding of current and historical groundwater storage and depletions of interconnected surface water
▪ Estimating Subbasin sustainable yield
▪ Evaluating impact of demand reduction on Subbasin sustainability ▪ Evaluating impact of climate change on Subbasin sustainability ▪ Developing or evaluating Sustainable Management Criteria (SMC) for groundwater levels, groundwater storage, and depletion of interconnected surface water ▪ Evaluating projects and management actions needed to reach sustainability ▪ Providing information on Subbasin data gaps or focus needs The annual update on the model is estimated to cost $100,000. The Final 2024 GSP Amendment should include a schedule of workshops regarding the model that are held on zoom/teams and that are recorded so that members of the public can have a better understanding of the consequences of various assumptions. Additionally, there should be an avenue by which stakeholders can discuss questions and concerns regarding the model.

Model updated assumptions were considered, with and without climate change, to develop projected conditions baseline with demand reduction and with projects and management actions. In order to “fit” the model to zero average annual storage changes, two assumptions were used and disclosed:
• Urban Demand: Urban per capita water use was reduced by 15% under both model conditions. This reduction is not indicative of how potential future urban demand cutbacks may be implemented.
• Agricultural Demand: Agricultural groundwater pumping was reduced in areas further than one (1) mile from streams by reducing agricultural acreage. Larger users of agricultural groundwater in ESJWRM were reduced at higher percents compared to smaller users. This reduction is not indicative of how potential future agricultural demand cutbacks may be implemented.

The conditions and assumptions used for the climate change baseline included DWR climate related guidance using a future scenario of 2070 climate forecasts that combined 10 global climate models (GCMs) for two different representative climate pathways to generate central tendency scenarios in the datasets used in this analysis. Discussions about these conditions and assumptions with the general public are needed to increase understanding of expected changes in conditions, particularly when making assumptions that may or may not be implemented regarding changes in water use within the subbasin.

The Final 2024 GSP Amendment should include a description of these climate pathways developed by DWR as there may be other applications of these pathways as communities develop climate resiliency plans and NOAA releases updated precipitation frequency estimates. Communities in San Joaquin, Stanislaus, and Calaveras counties have ATTACHMENT 2

experienced in the last five years the hottest temperatures, longest droughts, and intense precipitation storms causing flooding and loss of life.

How or if this guiding ad hoc program management committee considered the disadvantaged communities throughout the Eastern San Joaquin Subbasin was not disclosed though a map of those areas deemed disadvantaged by the State of California was provided in the Draft 2024 GSP Amendment as included below.

Large proportions of
the eastern
disadvantaged
communities in the
subbasin are colocated where the
greatest decrease in
groundwater levels
have occurred related
to over pumping of
groundwater. The over
pumping in these rural
area in eastern San
Joaquin County is
principally related to
agricultural
development as shown
in the groundwater
pumping density
diagram from the
model for conditions
where there was the
assumption of demand
reduction which may or
may not be a program
that is developed
and/or implemented.

Over pumping
groundwater not only
impacts disadvantaged
communities but all
well owners can be
significantly affected
when a well goes dry or
decreased yields
experienced.

ATTACHMENT 2

The 7.6.2023 DWR determination that the 2022 Revised GSP was approved, included within the Draft 2024 GSP Amendment, recommended that several corrective actions be incorporated into GSP updates including the human right to water and protective minimum thresholds. Technical Memorandum No. 1 – Groundwater Levels (TM-1) dated 10.1.2024 described the updated approach to minimum threshold above which undesirable results should not occur. Release of this TM-1 that while dated 10.1.2024 was reported to have been completed months ago, in advance of 10.1.2024, would have been an important gesture of an openness and transparency during the GSP development process.

The 2024 minimum thresholds overall were deemed more protective of drinking water sources. The 23 representative monitoring wells shown on the map below are those whose water depth is the basis of determining if the sustainable goals are achieved. The TM-1 stated that new minimum thresholds were included in the Draft 2024 GSP Amendment with six of the representative monitoring wells having new groundwater minimum threshold levels which were increased by an average of 7.6 feet, and three wells having new minimum threshold levels which were lowered by an average of 1.7 feet. Also reported was the installation of new nested monitoring wells to fill some data gaps. When comparing the areas of heavy agricultural groundwater extraction, disadvantaged communities, and well distribution, concerns remain that “no undesirable results” can be a paper exercise even with considering an extended radius around the representative monitoring wells.

The ESJGWA Board maintains that the domestic well and small water system drought readiness relating to SB552 implementation is a San Joaquin County project having nothing to do with the SGMA. DWR specific guidance regarding the relationship between the SGMA and SB552 was provided in links to the County and ESJGWA.12 There have 12 Alignment and Coordination Water Shortage Planning for Rural Communities and Sustainable Groundwater Management. March 2023
ATTACHMENT 2

been no public meetings resembling a domestic well and small water system drought task force other than a verbal presentation by OES/SJC Public Works at a San Joaquin Advisory Water Commission meeting last summer. The San Joaquin Advisory Water Commission that meets rarely was suggested to be the forum for the drought domestic well and small water system task force. The Final 2024 GSP Amendment must include a discussion of how this coordination and alignment outlined in DWR guidance will be implemented.

The ESJGWA Board of Directors have continued to attest that the Subbasin did not experience significant numbers of dry wells as included in the Resolution adopting a dry domestic well mitigation program.

The DSG has submitted periodically screenshots from the DWR My Dry Well database and submitted comments in April 2024 which included the following regarding dry wells in addition to recommendations and comments regarding the draft dry well mitigation program.

On March 6, 2024, the DWR released Groundwater Well Permitting Report - Observations and Analysis of Executive Orders N-7-22 and N-3-23 which included San Joaquin County in the top 10 counties with dry wells since March 28, 2022 as shown below.13 These DWR dry well data are reported voluntarily and would not include reports by individuals within a GSA.

While San Joaquin County groundwater users have not experienced dry wells as frequently as Fresno County, San Joaquin County experienced 20% more occasions of a well going dry than neighboring Stanislaus County. Once again, we disagree with the characterization that “the GSAs in the Eastern San Joaquin Subbasin have not experienced significant dry well reports as reported by the State of California Dry Well Reporting System or as reported by individuals within the GSAs.” 13 https://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Groundwater-Management/Wells/Files/DWRWell-Permitting-Analysis-Final_March2024.pdf?utm_medium=email&utm_source=govdelivery ATTACHMENT 2

A well mitigation program was adopted by the Board of Directors of the Eastern San Joaquin Groundwater on 9.11.2024 and included in Appendix 3-J. The DSG submitted comments regarding drafts of the well mitigation program. Once a draft program was drafted and made available for review, the DSG received no indication that the submitted comments were received or considered. The DSG looks forward to opportunities to provide comments as the dry well mitigation is implemented and processes developed.

The Final 2024 GSP Amendment should include a dated and finalized dry domestic well mitigation program and a timeline for the program implementation with specific steps that can be monitored for accountability. The DSG appreciates the efforts of the North San Joaquin Water Conservation District including Steve Schwabauer and Jennifer Spaletta for their leadership in drafting up an initial concept outline for the program which has been requested for many years and which we were invited to comment along with Clean Water Action on the initial concept outline. An acknowledgement was received but further opportunities to be involved in discussions/dialogues were not presented other than formal comments which were submitted in March and April 2024 by the DSG. A response to comments or a disclosure of comments received was not provided. Of course, a California Public Records Act request can be made but since the SGMA specifically included a requirement to engage with stakeholders in the development and implementation of GSPs, the expectation is that information would be readily available to interested parties without the need for a formal PRA submittal to county counsel.

Please reach out to discuss any issue which has been presented and we look forward to reading the Final 2024 GSP Amendment and submitting comments to DWR.

Sincerely,
Mary Elizabeth M.S., R.E.H.S.,
Delta-Sierra Group, Conservation Chair, Sierra Club
[email protected]
Margo Praus
Delta-Sierra Group Chair, Sierra Club
cc: Sean Wirth, Mother Lode Chapter Conservation Chair, Sierra Club ATTACHMENT 2
Stockton Environmental Justice
Education and Advocacy
Eastern San Joaquin Groundwater Authority Board 10.31.2024 Members of the GSAs in the Eastern San Joaquin Subbasin P. O. Box 1810, Stockton, CA 95201
via [email protected]
Re: Draft Eastern San Joaquin Groundwater Sustainability Plan Amendment (2024) While celebrating homecoming and the 100 year anniversary of the University of the Pacific in Stockton, CA I heard a talk by the Stockton Poet Laurate, Jazmarie LeTour, about voices and advocacy and was inspired to write this poem.

Ode to Outreach
Same Old, Same Old, Same Old
Broken record that skips, skips, skips
Over the parts that allow all groundwater users to meaningfully engage with the development and implementation of the plan, the plan, the plan For what, for what, for what
Expediency, privacy, withholding of power, because we know better, and you know your place, know your place, know your place
By Mary Elizabeth, October 16, 2024
Please do better because the stakeholders in the Eastern San Joaquin Subbasin are valuable components of sustainable solutions.

Sincerely,
Mary Elizabeth, M.S., R.E.H.S.
[email protected]
ATTACHMENT 2
APPENDIX 1-J.

RESPONSE TO PUBLIC COMMENTS
2024
Groundwater Sustainability Plan Amendment
Complete Appendices November 2024
ATTACHMENT 2
Comment # Commenter
Name
Organization Represented
Date Comment Received
Response
A-1 Brent Barton Barton Ranch 10/3/2024 It continues to be the intent and overarching goal of the Subbasin to reach sustainability through the implementation of projects. It is the responsibility of individual GSAs to plan for, fund, and implement projects that best meet their needs. The Demand Management Program is designed to be a backstop in the event that projects are not sufficient in helping the Subbasin reach sustainability.

B-1 Morgan Kilgour California Department
of Fish & Wildlife
10/30/2024 An expanded explanation of the data limitations to identifying potential GDEs was included in Appendix 3-C to include the lack of monitoring wells near GDEs. This is highlighted more clearly as a data gap within the GSP. This data gap will be filled by a commitment, on the part of the GSAs, to doing a field verification exercise at identified potential GDEs to evaluate water source and species present. This field verification will be completed by the 2030 Periodic Evaluation.

B-2 Morgan Kilgour California Department
of Fish & Wildlife
10/30/2024 Once the field verification study is complete ahead of the 2030 Periodic Evaluation, the results of the study will inform what type of Projects & Management Actions might be needed to reduce impacts on the identified GDEs. This PMA would be included in a 2030 GSP Amendment, if it is needed.

B-3 Morgan Kilgour California Department
of Fish & Wildlife
10/30/2024 As noted by CDFW, because of the lack of groundwater level data and site-specific surface water availability information, it is a challenge to differentiate a potential GDE that has partial reliance on GW with the current toolset available. Field verification of potential GDEs planned to address these data gaps will provide valuable information to confirm presence of GDEs and associated water availability.

B-4 Morgan Kilgour California Department
of Fish & Wildlife
10/30/2024 Figure 3 in the ISW TM displays the percentage of time that streams are connected in the ESJWRM. The text was revised to reflect that 75% connectivity time does not indicate if streams are considered ISWs or not, but is rather used as a comparison point for the analysis since the model outputs show that most of the major rivers are connected at least 80% of the time historically. Additionally, due to insufficient shallow groundwater data near surface water courses in the Eastern San Joaquin Subbasin, there is significant uncertainty in model calibration and the identification of interconnected surface waters (ISWs), which is required by GSP regulations. This will be reevaluated in the 2025 Periodic Evaluation, as mentioned in the response to comment B-10.

B-5 Morgan Kilgour California Department
of Fish & Wildlife
10/30/2024 The analysis of small streams and creeks in the 2024 GSP Amendment was limited by data availability, not by the use of streams/creeks for irrigation conveyance. Major streams and creeks are included in the ESJWRM model and calibrated with observed streamflow data. Several small streams and creeks do not have gages on them, which makes data input and calibration more challenging. The ISW TM will be amended to reflect that small streams and creeks were excluded because of data availability and the identification of these water bodies for ISW analysis will be included as a data gap.

B-6 Morgan Kilgour California Department
of Fish & Wildlife
10/30/2024 The GSAs currently do not have the tools required to confidently establish an SMC based on volume, timing, and rate of depletions due to groundwater pumping. In the absence of timely DWR guidance, groundwater levels are used for the ISW SMC since they can be directly measured and facilitate proactive monitoring and management of stream depletions, without depending on model simulations with a degree of uncertainty. As mentioned in the response to comment B-10, additional ISW analyses will be conducted before the next 5-year GSP update.

B-7 Morgan Kilgour California Department
of Fish & Wildlife
10/30/2024 Before publicly displaying the simulated stream-aquifer interactions on a sub-reach and monthly scale, additional streamflow and groundwater level data from shallow perforate wells should be collected to validate and increase certainty in the spatial and temporal findings on a refined scale. A refined analysis of ISW is noted as a data gap. Additionally, the frequency of monitoring of some ISW RMN wells will be increased with transducers funded from the ARPA to enhance understanding of stream-aquifer interactions and model calibration.

ATTACHMENT
2 Comment #
B-8
Commenter
Name
Morgan Kilgour
Organization Represented
California Department of Fish & Wildlife
Date Comment Received
10/30/2024
Response
Statements related to avoiding undesirable results because of rising Chinook salmon population in 2015 will be removed and the complexity of survival rates, spawning success, habitat availability, and other factors will be noted.

B-9 Morgan Kilgour California Department
of Fish & Wildlife
10/30/2024 Interim methodologies were considered during development of the ISW, however were excluded for various reasons.

At the time of analysis, there were no groundwater level observations since the wells are newly installed. There were insufficient nearby wells with shallow perforations and recent groundwater levels that could be used as a proxy. Lastly, simulated groundwater levels were not used to determine the SMCs since the ESJWRM is not calibrated to the level of certainty to solely establish ISW SMCs. Ultimately there are insufficient data to establish SMCs and a stable target to which to manage groundwater resources. Groundwater level observations at the new ISW representative monitoring network wells will be shared via Annual Reports and used to develop SMCs in the methodology described in the ISW TM.

B-10 Morgan Kilgour California Department
of Fish & Wildlife
10/30/2024 The ISW has been updated to include a commitment to reevaluating the ISW undesirable result and SMCs, with supporting analysis from the ESJWRM, before the next 5-year Periodic Evaluation. This allows for adequate time to include the latest DWR ISW guidance and ESJWRM model improvements.

C-1 Mitchell Maindrand City of Stockton 10/1/2024 Edits have been incorporated in the Periodic Evaluation, Executive Summary, Chapter 6, and Chapter 7.

C-2 Mitchell Maindrand City of Stockton 10/1/2024 Edits have been incorporated in the Periodic Evaluation, Executive Summary, Chapter 6, and Chapter 7. Note that although this will be listed as a Category A project, it will not be modeled.

D-1 Bana Rousan-Gedese Calaveras County Water
District
10/21/2024 Edits have been incorporated into Executive Summary.

D-2 Bana Rousan-Gedese Calaveras County Water
District
10/21/2024 Edits have been incorporated into Chapter 1.

D-3 Bana Rousan-Gedese Calaveras County Water
District
10/7/2024 Edits have been incorporated into Chapter 1.

D-4 Michael Minkler Calaveras County Water
District
10/31/2024 Comment noted. Wells that were previously in the Broad Monitoring Network can still be monitored and their data submitted to DWR.

D-5 Michael Minkler Calaveras County Water
District
10/31/2024 These are part of the new WQ network to provide vertical resolution of WQ in this part of the basin. Expectations are that these wells will be monitored for TDS and Chloride bi-annually. The GWA has contracted with Condor to complete this monitoring for the Subbasin. The monitoring will be billed to the appropriate agencies going forward.

D-6 Michael Minkler Calaveras County Water
District
10/31/2024 If these wells were part of the CASGEM reporting requirements, they will still be monitored and reported bi-annually as they have been historically. This data will continue to be available for any additional analysis of groundwater trends. Wells in the representative network are used to evaluate against sustainable management criteria under SGMA. CCWD has not had any representative monitoring network wells in the GSP to date including the 2024 Plan Amendment, but this can be reconsidered in the future.

D-7 Michael Minkler Calaveras County Water
District
10/31/2024 Analysis as part of the annual report looks at all wells with available data to assess groundwater conditions, beyond the representative monitoring networks. The representative wells are primarily used for assessing progress toward sustainability for the groundwater levels indicator.

D-8 Michael Minkler Calaveras County Water
District
10/31/2024 Comment noted. All GSAs are encouraged to continue pursuing projects that can support Subbasin sustainability.

ATTACHMENT
2 Comment #
E-1
Commenter
Name
Pat Dunn
Organization Represented
NV5
Date Comment Received
10/22/2024
Response
CCWD wells were part of the Broad monitoring network. The broad monitoring network was not used to evaluate progress toward sustainability and did not have SMC. To streamline monitoring efforts, the Broad monitoring network was removed from the GSP. Figure 4-5 has been replaced to remove reference to the Broad network, making it consistent with Tables 4-1 and 4-4.

F-1 Mary Elizabeth Delta-Sierra Group of
Sierra Club
9/11/2024 The Dry Domestic Well Mitigation Program was provided in the Public Draft as Appendix 3-J. The final GSP, once approved by the GSAs, will be posted on the esjgroundwater.org website.

F-2 Mary Elizabeth Delta-Sierra Group of
Sierra Club
9/11/2024 All GSAs are encouraged to add groundwater resources available to their residents on their respective webpages, including the Dry Domestic Well Mitigation Program documents.

F-3 Mary Elizabeth Delta-Sierra Group of
Sierra Club
9/11/2024 The GWA agrees that public engagement is important for an effective GSP. The Communication & Engagement plan being prepared under the DWR facilitation support services grant will address how the GWA can better reach more stakeholders.

G-1 Michael Machado,
Barbara BarriganParrilla, Ivan Senock, Sara Medina, Davis Harper Restore the Delta 10/31/2024 It continues to be the intent and overarching goal of the Subbasin to reach sustainability through the implementation of projects. It is the responsibility of individual GSAs to plan for, fund, and implement projects that best meet their needs.

G-2 Michael Machado,
Barbara BarriganParrilla, Ivan Senock, Sara Medina, Davis Harper Restore the Delta 10/31/2024 We understand the concerns regarding the diversion of funds and the impact on property owners. It is important to note that the administrative processes are designed to be equitable and consistent for all stakeholders. The goal is to ensure that everyone is subject to the same rules and procedures, which helps maintain fairness across the board. Additionally, Authority fees are essential for the successful implementation of the Sustainable Groundwater Management Act (SGMA). These fees support the necessary infrastructure and management efforts to achieve sustainable groundwater management, benefiting the entire community.

G-3 Michael Machado,
Barbara BarriganParrilla, Ivan Senock, Sara Medina, Davis Harper Restore the Delta 10/31/2024 Using a Facilitation Support Services grant from the Department of Water Resources, the GWA worked over the spring, summer, and fall of 2024 to solicit input and develop an updated Communication & Engagement Plan. This C&E Plan, provided as Appendix 1-H in the Final 2024 GSP Amendment, addresses how the GWA can improve its communications and community engagement efforts.

G-4 Michael Machado,
Barbara BarriganParrilla, Ivan Senock, Sara Medina, Davis Harper Restore the Delta 10/31/2024 Note that the City of Stockton has been pursuing grand funding to acquire funding for smart metering in South Stockton. PMAs that achieve groundwater sustainability benefit the entire basin, including South Stockton.

ATTACHMENT
2 Comment #
G-5
Commenter
Name
Michael Machado, Barbara BarriganParrilla, Ivan Senock, Sara Medina, Davis Harper Organization Represented
Restore the Delta
Date Comment Received
10/31/2024
Response
We have reviewed the paper by Deverel (2017) and acknowledge that the land and water use subsidence mitigation strategies proposed in the paper may present additional challenges such as potential water quality effects, infrastructure investments, and the potential loss of agricultural income due to altered land use or reduced crop yields. However, these issues fall outside the scope of this GSP as they involve altering land use practices, which is beyond the purview of the Sustainable Groundwater Management Act. Any land use decisions proposed to offset subsidence and achieve the subbasin's groundwater sustainability goals would require coordination between land use planning and groundwater management entities. These decisions must also ensure that the water use and accessibility of water for small farmers and DACs are still being considered, in accordance with AB 779. Regarding administrative burdens on small farmers, the public engagement process is designed to be inclusive and open to everyone, ensuring that all voices are heard. While we understand the concerns about the impact on small farmers, it is essential to have consistent administrative rules to maintain fairness and equity across the board. We are committed to finding a balance that supports small farmers while upholding these principles.

G-6 Michael Machado,
Barbara BarriganParrilla, Ivan Senock, Sara Medina, Davis Harper Restore the Delta 10/31/2024 Geologic CO2 sequestration projects fall under the California Environmental Quality Act (CEQA), which mandates additional monitoring. The Regional Monitoring Network (RMN) will oversee a regional and programmatic approach, rather than focusing on project-specific monitoring. Your concerns about integrating local groundwater monitoring programs and ensuring transparency with US EPA Class VI Underground Injection Control permits are noted and ideally regular testing for acidity levels near injection sites will be monitored on a project level through CEQA, outside of the GSP process.

H-1 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The GWA agrees that public engagement is important for an effective GSP. The Communication & Engagement plan being prepared under the DWR facilitation support services grant will address how the GWA can better reach more stakeholders.

H-2 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 There is no requirement under SGMA that Subbasins release the GSP for public comment prior to GSA adoption and submittal to DWR. As noted by the commenter, DWR holds a 30-day public comment period once the approved GSP is received by DWR.

H-3 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The Communication & Engagement plan being prepared under the DWR facilitation support services grant will address how the GWA can better reach more stakeholders. This plan will be provided with the final compiled GSP.

H-4 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The GSAs appreciate the commentor bringing this to the attention of the GWA; these materials are now posted. The posting of meeting materials is discussed in the Communication & Engagement (C&E) plan.

H-5 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 Because the 2024 GSP Amendment is an amendment to the 2020 GSP, work completed as part of the 2020 GSP remains relevant unless otherwise redlined or updated. Thus, components that the Workgroup meaningfully contributed to during the 2018-2019 stakeholder process remain relevant to the 2024 GSP Amendment. This includes the development of the Eastern San Joaquin Water Resources Model (ESJWRM), the development of the representative monitoring networks, the process for setting sustainable management criteria, and the development of projects and management actions, among other technical components. Technical aspects of amended components were discussed with the Project Management Committee (PMC) and administrative draft documents were provided to the GSAs during an Admin Review period. After GSA comments were addressed, the GSAs then released the Public Draft on October 1 for a 31-day public comment period. As noted by the commentor, DWR will also be providing an additional public review period within 20 days of receiving the 2024 GSP Amendment.

ATTACHMENT
2 Comment #
H-6
Commenter
Name
Mary Elizabeth & Margo Praus
Organization Represented
Delta-Sierra Group of Sierra Club
Date Comment Received
10/31/2024
Response
The GWA is in the process of re-evaluating how it plans to implement the new elements of the 2024 GSP Amendment, including the Communication & Engagement (C&E) plan. The commentor's concern related to recording meetings has been noted.

H-7 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The GWA is in the process of re-evaluating how it plans to implement the new elements of the 2024 GSP Amendment, including the Communication & Engagement (C&E) plan. The commentor's concern related to clarifying communication expectations has been noted.

H-8 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The GWA is in the process of re-evaluating how it plans to implement the new elements of the 2024 GSP Amendment, including the Communication & Engagement (C&E) plan. The commentor's concern related to posting meeting materials in advance has been noted.

H-9 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The GWA is in the process of re-evaluating how it plans to implement the new elements of the 2024 GSP Amendment, including the Communication & Engagement (C&E) plan. The commentor's concern related to hosting quarterly public meetings has been noted.

H-10 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The GWA is in the process of re-evaluating how it plans to implement the new elements of the 2024 GSP, including the C&E plan. These concerns about GWA process and governance have been noted and will be considered as part of that restructuring.

H-11 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The GWA is in the process of re-evaluating how it plans to implement the new elements of the 2024 GSP, including the C&E plan, Dry Domestic Well Mitigation Program, and the demand management program.

H-12 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 Information related to stakeholder engagement and public outreach activities conducted by the GSAs is reported each year in the Subbasin's Annual Report, which is submitted to DWR by April 1.

H-13 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 A list of PMC members have been incorporated into Chapter 1, Section 1.1.4.2.

H-14 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The GWA will soon begin the process of outlining a more detailed development schedule for the Demand Management Program, which it anticipates will include a series of workshops and opportunities for public participation and engagement.

H-15 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The assumptions made for urban and agricultural demand are preliminary in the 2024 GSP Amendment and were used as an initial assumption to provide a starting point from which demand management program discussions could begin. The GWA is planning to outline a more detailed schedule during which these numbers will be refined. This will be designed to be an iterative process to ensure broad agreement on the methodology and ensure the latest data is incorporated.

H-16 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 An explanation of the global climate models used by DWR is included in Appendix 2-B of the 2024 GSP Amendment.

H-17 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 San Joaquin County is responsible for implementing the requirements of SB552. Given the County's membership in the ESJGWA as a GSA, the ESJGWA will coordinate with and support the County where needed. The Dry Domestic Well Mitigation Program included in the 2024 GSP Amendment shares similar goals to those expected as a result of SB552 implementation.

H-18 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 The number of dry wells reported by the state for San Joaquin County are reported annually in the GSP's annual report. In San Joaquin County there were 12 reported water shortages due to dry wells between March 2023 and March 2024. The GWA's new Dry Well Mitigation Program is designed to step in to mitigate impacts of wells that go dry.

H-19 Mary Elizabeth &
Margo Praus
Delta-Sierra Group of Sierra Club
10/31/2024 Public comments received at the June 26, 2024 informational meeting, March 13, 2024 Steering Committee meeting, April 10, 2024 Steering Committee meeting, and August 14, 2024 Steering Committee meeting were considered prior to the GWA adopting the program at its September 11, 2024 GWA Board meeting. The GSAs welcome input as the program is implemented.

ATTACHMENT
2 Comment # Commenter
Name
H-20 I-1
Mary Elizabeth & Margo Praus Mary Elizabeth
Organization Represented
Delta-Sierra Group of Sierra Club Self
Date Comment Received
10/31/2024 11/1/2024
Response
The Dry Domestic Well Mitigation Program was provided in the Public Draft as Appendix 3-J. The final GSP, once approved by the GSAs, will be posted on the esjgroundwater.org website. The GWA is in the process of re-evaluating how it plans to implement the new elements of the 2024 GSP Amendment, including the Communication & Engagement (C&E) plan. This concern related to ensuring meaningful engagement during GSP implementation has been noted.

ATTACHMENT
2 2024
Groundwater Sustainability Plan Amendment
Complete Appendices November 2024
APPENDIX 1-K.

NOTICE OF INTENT TO ADOPT THE 2024 GSP AMENDMENT
ATTACHMENT 2
1419529-2
1 Water Code §§ 10 720, et seq.
2 DWR’s letter determination can be accessed on DWR’s SGMA Portal website:
https://sgma.water.ca.gov/portal/gsp/status
Board Members:

San Joaquin County
Robert Rickman - Chair
Stockton East Water
District
Mel Panizza - Vice Chair
California Water Service
Company
Jeremiah Mecham
Central Delta Water
Agency
George Biagi Jr.

Central San Joaquin Water
Conservation District
Grant Thompson
City of Lodi
Alan Nakanishi
City of Manteca
David Breitenbucher
City of Stockton
Dan Wright
Eastside San Joaquin GSA
Gary Tofanelli
Linden County Water
District
Myron Blanton
Lockeford Community
Services District
Mike Henry
North San Joaquin Water
Conservation District
Jason Colombini
Oakdale Irrigation District
Eric Thorburn
South Delta Water Agency
John Herrick
South San Joaquin
Irrigation District
Robert Holmes
Woodbridge Irrigation
District
Keith Bussman
July 24, 2024
Via E-mail and U.S. Mail
Calaveras County
San Joaquin County
Stanislaus County
City of Escalon
City of Lodi
City of Manteca
City of Ripon
City of Stockton
Re: Notice of Intent to Adopt an Amended Groundwater Sustainability Plan On behalf of the Groundwater Sustainability Agencies (“GSAs”) comprising the Eastern San Joaquin Groundwater Authority (collectively, the “GSAs”, as listed below), the Eastern San Joaquin Groundwater Authority (“Authority”) hereby gives notice on behalf of its members that the GSAs intend to adopt an amended Groundwater Sustainability Plan for the Eastern San Joaquin Subbasin pursuant to California Water Code Section 10728.4. Pursuant to this section, this notice is provided to the cities and counties within the area of the proposed amended GSP.

The GSP, originally adopted by the GSA members of the Authority, was submitted to the Department of Water Resources (“DWR”) on January 29, 2020, in compliance with the Sustainable Groundwater Management Act.1DWR completed its two-year review, and by letter dated January 28, 2022, determined the GSP to be incomplete and identified corrective actions to be completed within 180 days of the determination.2On July 27, 2022, the GSP was resubmitted to DWR. By letter dated March 2, 2023, DWR approved the resubmitted GSP and included a list of eight Recommended Corrective Actions to address in the Periodic Evaluation due January 2025.
______________________________________________________
ATTACHMENT 2
Notice of Intent to Adopt an Amended Groundwater Sustainability Plan June 24, 2024

The GSAs intend to address the Recommended Corrective Actions as part of the Periodic Evaluation and anticipate amending the GSP as a result. Each of the GSAs intends to hold separate public hearings to consider adoption of the amended GSP no sooner than ninety (90) days from the date of this notice.

Cities or counties that receive this notice may request in writing to consult on the proposed amended GSP. Please submit any such requests to the undersigned using the contact information below within thirty (30) calendar days of receipt of this notice.

For further information regarding the amended GSP, to download copies of the public draft of the amended GSP, and for other information regarding the amendment and readoption of the GSP, please visit www.esjgroundwater.org.

Sincerely,
Fritz Buchman, C.E., T.E., CFM
Eastern San Joaquin Subbasin Plan Manager
[email protected]
209-468-3100
GSAs in the Eastern San Joaquin Groundwater Subbasin:

Central Delta Water Agency
Central San Joaquin Water Conservation District
City of Lodi
City of Manteca
City of Stockton
Eastside San Joaquin GSA
Linden County Water District
Lockeford Community Services District
North San Joaquin Water Conservation District
Oakdale Irrigation District
San Joaquin County GSA No. 1
San Joaquin County GSA No. 2
South Delta Water Agency
South San Joaquin GSA
Stockton East Water District
Woodbridge Irrigation District
ATTACHMENT 2
ATTACHMENT 2
2024
Groundwater Sustainability Plan Amendment
Complete Appendices November 2024
APPENDIX 2-A.

EASTERN SAN JOAQUIN WATER RESOURCES MODEL
(ESJWRM) REPORT
ATTACHMENT 2
Eastern San Joaquin
Water Resources Model (ESJWRM)
AUGUST 2018
ATTACHMENT 2

EASTERN SAN JOAQUIN WATER RESOURCES MODEL
(ESJWRM)
Final Report
August 2018
Prepared by
ATTACHMENT 2
San Joaquin County i Woodard & Curran
ESJWRM Report August 2018

TABLE OF CONTENTS
SECTION PAGE NO.

EXECUTIVE SUMMARY .................................................................................................................. ES-1

1. INTRODUCTION ......................................................................................................................1-1

1.1 Goals of Model Development ...............................................................................................1-1

1.2 Eastern San Joaquin Groundwater Subbasin.........................................................................1-1

1.3 Local Coordination ..............................................................................................................1-2

1.4 Model Platform ...................................................................................................................1-2

2. MODEL DEVELOPMENT...........................................................................................................2-4

2.1 Model Input Data ................................................................................................................2-4

2.2 Model Grid and Reporting Units............................................................................................2-5

2.3 Stream Configuration and Stream Inflow ...............................................................................2-6

2.4 Precipitation .......................................................................................................................2-8

2.5 Root Zone Soil Parameters..................................................................................................2-8

2.6 Land Use and Cropping Patterns..........................................................................................2-9

2.7 Evapotranspiration ............................................................................................................2-11

2.8 Drainage ..........................................................................................................................2-12

2.9 Model Layering .................................................................................................................2-12

2.10 Small-Stream Watersheds .................................................................................................2-13

2.11 Boundary Conditions .........................................................................................................2-13

2.12 Initial Conditions ...............................................................................................................2-14

3. WATER SUPPLY AND DEMAND DATA.......................................................................................3-1

3.1 Agricultural Water Demand ..................................................................................................3-1

3.2 Urban Water Use ................................................................................................................3-1

3.3 Water Supply Summary.......................................................................................................3-2

3.3.1 Surface Water...........................................................................................................3-2

3.3.2 Groundwater Pumping...............................................................................................3-6

3.4 Water Supply Sources.........................................................................................................3-7

3.4.1 Delta Areas ..............................................................................................................3-7

3.4.2 Woodbridge Irrigation District .....................................................................................3-8

3.4.3 City of Lodi ...............................................................................................................3-8

3.4.4 North San Joaquin Water Conservation District............................................................3-8

3.4.5 Lockeford Community Services District .......................................................................3-9

3.4.6 Calaveras County......................................................................................................3-9

3.4.7 Stockton Area ...........................................................................................................3-9

3.4.8 Stockton East Water District.......................................................................................3-9

3.4.9 Linden County Water District....................................................................................3-10

3.4.10 Central San Joaquin Water Conservation District .......................................................3-10

3.4.11 South San Joaquin Irrigation District .........................................................................3-10

3.4.12 City of Lathrop ........................................................................................................3-11

3.4.13 City of Manteca.......................................................................................................3-11 ATTACHMENT 2
San Joaquin County ii Woodard & Curran
ESJWRM Report August 2018

3.4.14 City of Ripon...........................................................................................................3-11

3.4.15 City of Escalon........................................................................................................3-11

3.4.16 Oakdale Irrigation District.........................................................................................3-12

3.4.17 Cosumnes Subbasin ...............................................................................................3-12

3.4.18 Modesto Subbasin ..................................................................................................3-12

3.4.19 Riparian Diverters ...................................................................................................3-12

4. MODEL CALIBRATION.............................................................................................................4-1

4.1 Model Calibration................................................................................................................4-1

4.2 Calibration of the IDC and Root-Zone Parameters..................................................................4-1

4.3 Calibration of Surface Water Features ..................................................................................4-2

4.4 Calibration of Water Budgets................................................................................................4-3

4.4.1 Land and Water Use Budget ......................................................................................4-3

4.4.2 Groundwater Budget .................................................................................................4-4

4.5 Groundwater Level Calibration .............................................................................................4-5

4.6 Measurement of Calibration Status .......................................................................................4-6

4.7 Final Calibration Parameters................................................................................................4-6

4.8 Sensitivity Analysis..............................................................................................................4-7

4.8.1 Sensitivity Analysis Results ........................................................................................4-8

5. CONCLUSIONS .......................................................................................................................5-1

6. REFERENCES.........................................................................................................................6-1 TABLES
Table 1: ESJ Subbasin GSAs and Member Agencies
Table 2: Physical Model Boundaries
Table 3: ESJWRM Major Model Data
Table 4: Model Subregions and Subareas
Table 5: Summary of ESJWRM Stream Inflow Data
Table 6: Land Use Categories
Table 7: Summary of ESJWRM Surface Water Deliveries
Table 8: Summary of ESJWRM Well Pumping
Table 9: Summary of ESJWRM Stream Calibration Gauges
Table 10: Range of Aquifer Parameter Values

FIGURES
Figure 1: ESJ Subbasin with County Lines
Figure 2: Groundwater Subbasins
Figure 3a: ESJ Subbasin Major Water Purveyors
Figure 4: ESJWRM Boundaries
Figure 5: ESJWRM Grid Development Features
Figure 6: ESJWRM Elements
Figure 7: ESJWRM Subregions
Figure 8: ESJWRM Subareas
Figure 9: ESJWRM Streams and Stream Inflow Locations
ATTACHMENT 2
San Joaquin County iii Woodard & Curran
ESJWRM Report August 2018
Figure 10: ESJWRM Average Annual Precipitation
Figure 11: ESJWRM Annual Rainfall
Figure 12: ESJWRM Hydrologic Soil Group
Figure 13: ESJWRM General Land Use in 1995 DWR Land Use Survey Figure 14: ESJWRM General Land Use in 2015 CropScape
Figure 15: ESJWRM ESJ Subbasin Annual General Land Use
Figure 16: ESJWRM Cropping Pattern in 1995 DWR Land Use Survey Figure 17: ESJWRM Cropping Pattern in 2014 Land IQ
Figure 18: ESJWRM Cropping Pattern in 2015 CropScape
Figure 19a: ESJWRM Annual Cropping Pattern – Eastern San Joaquin Subbasin Figure 20: ESJWRM Annual Evapotranspiration
Figure 21: ESJWRM Surface Water Drainage Watersheds
Figure 22: ESJWRM Ground Surface Elevation
Figure 23: ESJWRM Layer 1 Thickness
Figure 24: ESJWRM Corcoran Clay Depth to Top
Figure 25: ESJWRM Corcoran Clay Thickness
Figure 26: ESJWRM Layer 2 Thickness
Figure 27: ESJWRM Layer 3 Thickness
Figure 28: ESJWRM Layer 4 Thickness
Figure 29a: ESJWRM Cross Section A - A’
Figure 30: ESJWRM Small Watersheds
Figure 31: ESJWRM Initial GW Levels (Fall 1994)
Figure 32: ESJWRM Annual Population by Urban Center
Figure 33: ESJWRM Annual Per Capita Water Use by Urban Center Figure 34: ESJWRM Surface Water Diversion Locations
Figure 35: ESJWRM Groundwater Production Wells
Figure 36: ESJWRM Riparian Surface Water Diversion Areas Figure 37: ESJWRM Field Capacity
Figure 38: ESJWRM Wilting Point
Figure 39: ESJWRM Total Porosity
Figure 40: ESJWRM Saturated Hydraulic Conductivity
Figure 41: ESJWRM Pore Size Distribution Index
Figure 42a: ESJWRM Agricultural Water Demand – Eastern San Joaquin Subbasin Figure 43a: ESJWRM Urban Water Demand – Eastern San Joaquin Subbasin Figure 44: ESJWRM Stream Calibration Gauges
Figure 45: ESJWRM Stream Bed Hydraulic Conductivity
Figure 46a: ESJWRM Stream Calibration Gauges Streamflow – Dry Creek near Galt Figure 47a: ESJWRM Agricultural Land and Water Use Budget – Eastern San Joaquin Subbasin Figure 48a: ESJWRM Urban Land and Water Use Budget – Eastern San Joaquin Subbasin Figure 49a: ESJWRM Groundwater Budget – Eastern San Joaquin Subbasin Figure 50: ESJWRM Groundwater Level Calibration Wells
Figure 51a: ESJWRM Groundwater Level Contours (Fall 2015) Figure 52a: ESJWRM Groundwater Level Hydrograph – Hydrograph #1 Figure 53: ESJWRM ESJ Subbasin Groundwater Level Histogram Figure 54: ESJWRM ESJ Subbasin Groundwater Level Scatter Plot Figure 55: ESJWRM Parametric Grid
Figure 56: ESJWRM Layer 1 Horizontal Hydraulic Conductivity Figure 57: ESJWRM Layer 2 Horizontal Hydraulic Conductivity ATTACHMENT 2
San Joaquin County iv Woodard & Curran
ESJWRM Report August 2018
Figure 58: ESJWRM Layer 3 Horizontal Hydraulic Conductivity Figure 59: ESJWRM Layer 1 Specific Storage
Figure 60: ESJWRM Layer 2 Specific Storage
Figure 61: ESJWRM Layer 3 Specific Storage
Figure 62: ESJWRM Layer 1 Specific Yield
Figure 63: ESJWRM Layer 2 Specific Yield
Figure 64: ESJWRM Layer 3 Specific Yield
Figure 65: ESJWRM Sensitivity Analysis of Horizontal Hydraulic Conductivity – Difference in Average Groundwater Elevation (feet)
Figure 66: ESJWRM Sensitivity Analysis of Horizontal Hydraulic Conductivity – Relative Root Mean Square Error Figure 67: ESJWRM Sensitivity Analysis of Vertical Hydraulic Conductivity – Difference in Average Groundwater Elevation (feet)
Figure 68: ESJWRM Sensitivity Analysis of Vertical Hydraulic Conductivity – Relative Root Mean Square Error Figure 69: ESJWRM Sensitivity Analysis of Specific Storage – Difference in Average Groundwater Elevation (feet) Figure 70: ESJWRM Sensitivity Analysis of Specific Storage – Relative Root Mean Square Error Figure 71: ESJWRM Sensitivity Analysis of Specific Yield – Difference in Average Groundwater Elevation (feet) Figure 72: ESJWRM Sensitivity Analysis of Specific Yield – Relative Root Mean Square Error Figure 73: ESJWRM Sensitivity Analysis of Streambed Conductance – Difference in Average Groundwater Elevation (feet)
Figure 74: ESJWRM Sensitivity Analysis of Streambed Conductance – Relative Root Mean Square Error

APPENDICES
Appendix A: Presentations to Technical Review Committee Appendix B: ESJWRM IDC Technical Memorandum
Appendix C: ESJWRM Calibration Wells
ATTACHMENT 2
San Joaquin County v Woodard & Curran
ESJWRM Report August 2018

LIST OF ABBREVIATIONS
AF and AFY Acre-Feet and Acre-Feet Per Year
ASTM American Standard Testing Method
AWMP Agricultural Water Management Plan
C2VSim California Central Valley Groundwater-Surface Water Simulation Model Cal Water California Water Service Company Stockton District CALSIMETAW California Simulation of Evapotranspiration of Applied Water CASGEM California Statewide Groundwater Elevation Monitoring CCWD Calaveras County Water District
CDEC California Data Exchange Center
CFS Cubic Feet per Second
CIMIS California Irrigation Management Information System County San Joaquin County
CSJWCD Central San Joaquin Water Conservation District
CVHM Central Valley Hydrologic Model
DEM Digital Elevation Model
DWR California Department of Water Resources
ESJ Subbasin Eastern San Joaquin Groundwater Subbasin
ESJWRM Eastern San Joaquin Water Resources Model
ET Evapotranspiration
ETAW Evapotranspiration of Applied Water
GBA Eastern San Joaquin County Groundwater Basin Authority GMS Aquaveo Groundwater Modeling System
GPCD Gallons Per Capita Per Day
GSA Groundwater Sustainability Agency
GSE Ground Surface Elevation
GSP Groundwater Sustainability Plan
GWA Eastern San Joaquin Groundwater Authority
IDC IWFM Demand Calculator
IGSM Integrated Groundwater and Surface Water Model
IRWMP Integrated Regional Water Management Plan
IWFM Integrated Water Flow Model
KH Aquifer Hydraulic Conductivity
KV Aquifer or Aquitard Vertical Hydraulic Conductivity
LCSD Lockeford Community Services District
LCWD Linden County Water District
MAF and MAFY Million Acre-Feet and Million Acre-Feet Per Year METRIC Mapping Evapotranspiration at High Resolution with Internalized Calibration NASS National Agricultural Statistics Service
NRCS Natural Resource Conservation Service
NSJWCD North San Joaquin Water Conservation District
OID Oakdale Irrigation District
OSWCR Online System for Well Completion Reports
PRISM Precipitation-Elevation Regressions on Independent Slopes Model ATTACHMENT 2
San Joaquin County vi Woodard & Curran
ESJWRM Report August 2018
PSDI Pore Size Distribution Index
RMS Root Mean Square
SEWD Stockton East Water District
SGMA Sustainable Groundwater Management Act
SS Aquifer Specific Storage
SSJID South San Joaquin Irrigation District
SSURGO Soil Survey Geographic Database
STATSGO2 Digital General Soil Map of the United States
SY Aquifer Specific Yield
TAF and TAFY Thousand Acre-Feet and Thousand Acre-Feet Per Year USACE United States Army Corps of Engineers
USDA United States Department of Agriculture
USGS United States Geological Survey
UWMP Urban Water Management Plan
WDL Water Data Library
WID Woodbridge Irrigation District
ATTACHMENT 2
San Joaquin County vii Woodard & Curran
ESJWRM Report August 2018

ACKNOWLEDGEMENTS
In December 2015, San Joaquin County (County) applied for Proposition 1’s Counties with Stressed Basins Grant and received approval for $499,900. With a fifty percent cost share with the California Department of Water Resources, the County executed a contract with Woodard & Curran (formerly RMC Water and Environment), on September 13, 2016 to begin work on a hydrologic model for the Eastern San Joaquin Groundwater Subbasin. The purpose of the resulting model, the Eastern San Joaquin Water Resources Model (ESJWRM), is to support activities in long-term management of the Eastern San Joaquin Subbasin at the local scale, specifically focusing on meeting the goals and requirements of the Sustainable Groundwater Management Act.

A technical committee provided quality assurance and technical support throughout the project, resulting in a groundwater model widely accepted by local shareholders and public agencies. The committee was an informal group consisting of technical representatives from local agencies, consultants with knowledge of the area, representatives for neighboring groundwater subbasins, Department of Water Resources (DWR) staff, and San Joaquin County personnel. Local agencies with consistent representation included San Joaquin County, Woodbridge Irrigation District, City of Lodi, North San Joaquin Water Conservation District, Lockeford Community Services District, Calaveras County Water District, City of Stockton, California Water Service Company Stockton District, Stockton East Water District, City of Lathrop, City of Manteca, South San Joaquin Irrigation District, City of Escalon, Oakdale Irrigation District, and Stanislaus County.

The Main Project Team included:
• Woodard & Curran (formerly RMC Water and Environment) o Alyson Watson, Project Principal
o Ali Taghavi, Project Manager
o Sevim Onsoy, Project Support
o Jeanna Long, Data Management System Lead
o Sara Miller, Project Engineer
• NV5
ATTACHMENT 2
San Joaquin County ES-1 Woodard & Curran
ESJWRM Report August 2018

EXECUTIVE SUMMARY
The Eastern San Joaquin Water Resources Model (ESJWRM) was developed to evaluate the surface water and groundwater resources in the Eastern San Joaquin Groundwater Subbasin (ESJ Subbasin) during recent historical hydrologic conditions. This period covers water years 1995 through 2015, and includes several above normal and wet years, as well as the most recent drought conditions. The model is designed to simulate the regional water resources conditions in the ESJ Subbasin, including the land surface processes, groundwater operations, stream and river systems, and the interaction between these resources.

Development of the ESJWRM occurred in an open and
transparent process over approximately 24 months, starting in September 2016. Model development was a collaborative process between San Joaquin County staff, local water agencies, and Woodard & Curran, as consultant and developers of the model. The model was developed by partial funding from the Department of Water Resources (DWR), and as such, the DWR staff were engaged and collaborated in development of the model.

A technical committee provided quality assurance and technical support throughout the project, resulting in an integrated water resources model widely accepted by local shareholders and public agencies. The committee was an informal group consisting of technical representatives from local agencies, consultants with knowledge of the area, representatives from neighboring groundwater subbasins, DWR staff, and San Joaquin County personnel. Local agencies with consistent representation included San Joaquin County, Woodbridge Irrigation District, City of Lodi, North San Joaquin Water Conservation District, Lockeford Community Services District, Calaveras County Water District, City of Stockton, California Water Service Company Stockton District, Stockton East Water District, City of Lathrop, City of Manteca, South San Joaquin Irrigation District, City of Escalon, Oakdale Irrigation District, and Stanislaus County.

ESJWRM development followed a robust process as shown below. Modeling needs were established in early 2015, shortly after the passage of the Sustainable Groundwater Management Act (SGMA).

Subsequently, modeling goals and objectives were discussed and established, and San Joaquin County was successful in securing funds through Proposition 1 to begin development of the model.

ESJWRM development required a significant amount of data and information, including hydrologic, hydrogeologic, topographic and soil conditions, land use and cropping patterns, urban and agricultural water demand, urban and agricultural water supplies, surface water conveyance and distribution systems, groundwater infrastructure and extraction, and irrigation practices. The following figure shows the type ATTACHMENT 2
San Joaquin County ES-2 Woodard & Curran
ESJWRM Report August 2018
of data and information needed to develop the model. A collaborative process was followed to collect and analyze, fill data gaps, and develop proper assumptions for the use, context, and accuracy of the data, before analyzing and properly formatting the data for input in the model.

Once the model was constructed, appropriate state-of-the-art scientific and engineering protocols and guidelines were utilized to calibrate the model to ensure that:
• Water budgets generated by the model represent the regional and local understanding of the agricultural and urban entities represented in the model. The model-generated water budgets showing water demand and supply and the groundwater system are prepared and reported on both monthly and annual scales for urban and agricultural entities as well as at the subbasin scale. • Monthly groundwater levels generated by the model at select observation wells throughout the subbasin closely follow the long-term annual trends and short-term seasonal fluctuations that are recorded and reported at the observation wells.
• Monthly streamflow generated by the model at select gauging stations closely follow the high and low flows as reported.

The calibrated ESJWRM provides detailed conditions of the ESJ Subbasin over the calibration period of water years 1996 through 2015. This calibrated model can be used for understanding subbasin characteristics and the effects of historical surface water and groundwater operations as well as irrigation practices or urban operations on the groundwater and surface water resources in the ESJ Subbasin. These include:
• Historical and current levels of development
• Subbasin operations under natural conditions
• Nature, extent, and rates of stream-aquifer interaction ATTACHMENT 2
San Joaquin County ES-3 Woodard & Curran
ESJWRM Report August 2018
• Effects and benefits of upstream regulation of rivers on the operations of the groundwater subbasin
• Effects of operations of regional water supply projects, including conjunctive use, on subbasin conditions
• Evaluation of water quality conditions in the subbasin Additionally, the calibrated model can be used to develop baseline conditions representing projections of land use, population growth, water demand, and water supply conditions, as estimated based on local and regional planning activities. The baseline model, as a robust, defensible, and detailed tool, may be used for assessing the current and projected water resources conditions in the basin to support various local and regional planning projects and programs,
such as the development and implementation of a
Groundwater Sustainability Plan (GSP). ESJWRM may
also be used to evaluate the effectiveness of different projects that may be proposed through the GSP
development process. The fine scale of the model also
provides the opportunity for individual Groundwater
Sustainability Agencies (GSAs) to evaluate the effects
of ESJ Subbasin conditions on smaller GSA areas.

Some of the key features of the ESJWRM are as follows:

Model Platform
The model code platform is the DWR’s Integrated Water Flow Model (IWFM-2015). This code platform was developed by DWR to simulate the integrated hydrologic conditions of a groundwater basin, with interactions between the surface water, groundwater, and stream system. The code platform has specific strengths in the calculation of agricultural water demand in a predominantly agricultural area, such as the Eastern San Joaquin Subbasin. The code platform is supported by the DWR modeling support staff for local and regional applications, including SGMA implementation.

Model Area
The model covers the entire area of the Eastern San Joaquin Groundwater Subbasin, as defined by DWR Bulletin 118, as well as the areas of the Modesto and Cosumnes Groundwater Subbasins (the basins immediately north and south of the ESJ Subbasin). The model area is subdivided into small units (elements). A comprehensive integrated hydrologic process and analysis is conducted at each model element, and surface water and groundwater flows are calculated and simulated across elements, and throughout the entire model area on a monthly time step, in such a way that mass balance is preserved every month. Additionally, each element represents the geologic and hydrogeologic conditions of the subsurface environment as represented by four model layers in a conceptual context.

Project Evaluations

SGMA, IRWM, GWMP
Groundwater Banking
Water Availability
Groundwater
Sustainability
Urban Water Supply
Storm water and
Recycled Water
Opportunities
Hydro-Economic
Evaluations
Project Beneficiary
Assessment
ATTACHMENT 2
San Joaquin County ES-4 Woodard & Curran
ESJWRM Report August 2018
Hydrology
The model contains 50 years of hydrologic period (water years 1969 through 2018), which provides opportunities to assess the basin conditions during above normal, below normal, and drought periods.

The model is calibrated during the period of 1996-2015, during which there are more robust and defensible data available for model calibration. In addition, the model includes major and minor rivers and creeks in the area and calculates stream-aquifer interaction along the major rivers and creeks. The minor creeks and canals represented in the model are used for conveyance of irrigation water and drainage.

ATTACHMENT 2
San Joaquin County ES-5 Woodard & Curran
ESJWRM Report August 2018
Model Subareas
The model elements are aggregated into larger geographic areas, which represent individual agricultural and urban entities (Subregions) and larger planning areas (Subareas). These larger areas can be used to prepare model input data and to analyze model generated water budgets for planning purposes.

ATTACHMENT 2
San Joaquin County ES-6 Woodard & Curran
ESJWRM Report August 2018
Land Use and Agricultural Cropping Pattern
A key data set used in the model is the distribution of land between agricultural, urban, native, and riparian land use categories, as well as acreages of major crops in the agricultural lands. This information is prepared and processed based on land use surveys prepared and reported by the DWR (DWR, 1993- 2000), remote sensing data from the United States Department of Agriculture called CropScape (USDA NASS, 2007-2015), and the DWR Land IQ dataset (DWR, 2014). This information was compiled, analyzed, and evaluated for each model element; compared and cross-checked with data and information from the agricultural entities; and finalized for use in the model.

ATTACHMENT 2
San Joaquin County ES-7 Woodard & Curran
ESJWRM Report August 2018
Water Budgets
The model produces water budgets for land surface processes, including an estimate of urban and agricultural water demands, and water supplies. In addition, the model produces water budgets for the groundwater system, including groundwater pumping to meet irrigation demand and urban water needs, deep percolation from rainfall and irrigation applied water, subsurface flows from neighboring groundwater subbasins and the Sierra Nevada foothills, seepage from unlined conveyance canals, and flows between the stream and the aquifer system. The model can present this information on both a monthly and annual basis. Local operations data and information was collected from various water users and model parameters were adjusted to calibrate the model outcome to the reported values. Model calibration was conducted in an open and transparent process to ensure that the water budgets and model calibration results are properly representing the conditions of the groundwater basin to the extent that information is available.

An annual representation of the groundwater budget can reveal overall changes in groundwater storage, as depicted in the chart below. Uncertainties are inherent in every data set and calculation. Through a systematic sensitivity analysis, the range of impacts of uncertainties on model calculations was quantified.

Knowledge of this range of uncertainties can assist in providing flexibility in decisions that rely on model results. The average annual depletions in groundwater storage for the historical period of 1996-2015 is estimated to be about 24,000 to 70,000 acre-feet per year (AFY), with an average depletion of 47,000 AFY.

Groundwater Levels
The model-calculated groundwater levels are calibrated to observed groundwater levels at key wells over time. The typical goal of this calibration process is to adjust hydraulic parameters that influence the movement of groundwater such that the groundwater levels calculated by the model at the specific observation wells throughout the model area track short-term seasonal fluctuations and long-term trends as closely as possible. A typical model produced result is shown in the chart below. Once calibrated, the model produces regional groundwater levels for select points in time, as shown in the figure below. Model calibration statistics are represented in the following figures, which indicate that 75% of model calculated groundwater levels are within 10 feet of reported observations, and 97% are within 20 feet of reported observations. Given the uncertainties in the measurement of reported values, as well as uncertainties in model calculations, and expected calibration results for similar models as reported in the scientific communities, this statistic represents a very good model performance.

ATTACHMENT 2
San Joaquin County ES-8 Woodard & Curran
ESJWRM Report August 2018
Streamflows
The model calculates flow of water in the stream system throughout the basin. Streamflows are subject to the diversion of water for beneficial agricultural uses or urban consumption, return flows from irrigation practices, runoff of rainfall, as well as gains and losses due to interaction with the groundwater system. The model stream system is calibrated to reported flows at the downstream gauging stations. The chart below shows the comparison between model calculated streamflow and gauge records on Mokelumne River at Woodbridge. The results indicate that the model is capable of simulating both the low and the high flows reasonably well.

ATTACHMENT 2
San Joaquin County ES-9 Woodard & Curran
ESJWRM Report August 2018
Conclusions and Recommendations
The ESJWRM, in its current state, is a robust, comprehensive, defensible and well-established model for assessing the water resources in the ESJ Subbasin under historical and projected conditions. The following recommendations are to be considered for further refinements and enhancements of the model:
• Continue engagement with local groundwater users and managers. Continue working with local agencies and groundwater users in ESJ Subbasin to further understand the local operations of the groundwater system and improve representation of groundwater users in the ESJWRM. • Refinement of boundary flows. The current boundary flows at the northern, western, and southern boundaries of the model area are based on an older version of the C2VSim with adjustments made based on initial groundwater levels assumed for the beginning of the model (October 1994). DWR is currently in the process of updating the C2VSIm model. Once the latest fine grid version (C2VSim-2015) is publicly available, boundary flows for the ESJ model area should be verified and updated, as necessary.
• Enhance variability of potential evapotranspiration. The current version of the IDC used for estimation of the consumptive use of crops in the ESJWRM uses monthly potential ET values that are the same for all years during the model period. Given that there may be annual variability in the potential ET data with possible effects on the annual estimation of crop water demand, it is recommended to use more detailed data with temporal variability to develop a full time series of ET values for use in the model.
• Refine surface water deliveries in Cosumnes and Modesto Subbasins. The surface water deliveries in the Cosumnes and Modesto Subbasins are currently at the subregion level and do not have the detailed spatial resolution of other areas within the ESJ Subbasin. This data may need to be verified and updated as modeling efforts in those subbasins progress to meet the requirements of SGMA.
• Update C2VSim based on ESJWRM. The fine grid version of C2VSim was developed by the DWR to evaluate the integrated surface water and groundwater conditions at a regional scale; whereas, the ESJWRM is capable of evaluation at the local scale. To increase the accuracy of regional groundwater conditions in the fine grid C2VSim, the County is encouraged to work with DWR to provide data and information for further refinement and update of C2VSim in the ESJWRM area. • Develop model update schedule. In order to keep the ESJWRM up-to-date and current for analysis of water resources and especially for supporting SGMA implementation, it is recommended that the model be updated every 3 to 5 years. A possible update schedule can be kept consistent with the GSP updates, with a lead time of 2 to 3 years relative to the GSP update schedule.

ATTACHMENT 2
San Joaquin County 1-1 Woodard & Curran
ESJWRM Report August 2018

1. INTRODUCTION

1.1 Goals of Model Development
The Eastern San Joaquin Water Resources Model (ESJWRM) was developed primarily to evaluate the current and recent historical groundwater conditions of the Eastern San Joaquin Groundwater Subbasin (ESJ Subbasin) and simulate various future condition scenarios as part of the Groundwater Sustainability Plan (GSP) preparation process under the Sustainable Groundwater Management Act (SGMA). ESJWRM will also be used to evaluate the effectiveness of different projects that may be proposed through the GSP development process. The fine scale of the model also provides the opportunity for individual Groundwater Sustainability Agencies (GSAs) to evaluate the effect of changing ESJ Subbasin conditions on smaller GSA areas.

1.2 Eastern San Joaquin Groundwater Subbasin
The ESJ Subbasin underlies portions of San Joaquin, Calaveras, and Stanislaus counties, with the majority of the area in San Joaquin County (Figure 1). San Joaquin County is located in the northeastern San Joaquin Valley and contains portions of the Sacramento-San Joaquin River Delta.

In 2014, the ESJ Subbasin was categorized as a high priority groundwater subbasin under the California Statewide Groundwater Elevation Monitoring (CASGEM) program. The ESJ Subbasin has been identified by the California Department of Water Resources (DWR) as critically overdrafted and is included in the List of Critically Overdrafted Basins finalized in January 2016. As a critically overdrafted subbasin, GSAs in the ESJ Subbasin must develop a GSP by January 31, 2020 that details how the ESJ Subbasin will be managed in a sustainable manner by 2040. The other groundwater subbasins immediately surrounding the ESJ Subbasin are not critically overdrafted except for the Delta-Mendota Subbasin (Figure 2).

The major municipalities in the ESJ Subbasin are the cities of Lodi, Stockton (including California Water Service Company Stockton District or Cal Water), Lathrop, Manteca, Ripon, and Escalon. The major agricultural water providers in the ESJ Subbasin include Woodbridge Irrigation District (WID), North San Joaquin Water Conservation District (NSJWCD), Stockton East Water District (SEWD), Central San Joaquin Water Conservation District (CSJWCD), South San Joaquin Irrigation District (SSJID), and Oakdale Irrigation District (OID). The major municipalities and agricultural water providers are all GSAs. Other agencies which supply water or have land use authority within the ESJ Subbasin and have been designated as GSA’s are San Joaquin County, Stanislaus County (in combination with CCWD and Rock Creek Water District), Calaveras County Water District (CCWD), North and South Delta Water Agencies, Lockeford Community Services District (LCSD), and Linden County Water District (LCWD). The 17 GSAs covering ESJ Subbasin and their corresponding member agencies are listed in Table 1. The water purveyors are shown in Figure 3a and the GSAs are shown in Figure 3b.

Table 1: ESJ Subbasin GSAs and Member Agencies
GSA Member Agency
Central Delta Water Agency Central Delta Water Agency
Central San Joaquin Water
Conservation District Central San Joaquin Water Conservation District City of Lathrop City of Lathrop
City of Lodi City of Lodi
ATTACHMENT 2
San Joaquin County 1-2 Woodard & Curran
ESJWRM Report August 2018
GSA Member Agency
City of Manteca City of Manteca
City of Stockton City of Stockton
Eastside San Joaquin GSA
Calaveras County Water District
Stanislaus County
Rock Creek Water District
Linden County Water District Linden County Water District Lockeford Community
Services District Lockeford Community Services District North San Joaquin Water
Conservation District North San Joaquin Water Conservation District Oakdale Irrigation District ESJ
Subbasin GSA Oakdale Irrigation District
San Joaquin County San Joaquin County
San Joaquin County No. 2 San Joaquin County
Cal Water
South Delta Water Agency South Delta Water Agency
South San Joaquin GSA
South San Joaquin Irrigation District
City of Ripon
City of Escalon
Stockton East Water District Stockton East Water District Woodbridge Irrigation
District
Woodbridge Irrigation District

1.3 Local Coordination
The development of the ESJWRM took place in an open and transparent process. The 17 GSAs of the ESJ Subbasin coordinate SGMA activities through the formation of the Eastern San Joaquin Groundwater Authority (GWA). The Eastern San Joaquin County Groundwater Basin Authority (GBA) was the organizational structure for agency coordination of water resources activities before SGMA regulations and the formation of the GWA. Many of the GBA/GWA agency members participated in a Technical Review Committee, which acted as the forum to review model input data and assumptions, as well as calibration results. The Technical Review Committee helped to facilitate major modeling decisions, provided input data, and reviewed results. The monthly Technical Review Committee meetings were open to all interested parties and generally consisted of technical representatives from local agencies, consultants with knowledge of the area, representatives for neighboring groundwater subbasins, DWR staff, and San Joaquin County personnel. Presentations given to this group are included in Appendix A and highlight major model configuration decisions, data analysis, and draft model results.

Local agencies with consistent representation at the Technical Review Committee meetings included San Joaquin County, WID, City of Lodi, NSJWCD, LCSD, CCWD, City of Stockton, Cal Water, SEWD, City of Lathrop, City of Manteca, SSJID, City of Escalon, OID, and Stanislaus County.

1.4 Model Platform
The ESJ Subbasin has been modeled since the mid-1980s. In 1993, as part of the Bureau of Reclamation’s American River Watershed Investigation, an integrated model was developed based on the Integrated ATTACHMENT 2
San Joaquin County 1-3 Woodard & Curran
ESJWRM Report August 2018
Groundwater and Surface Water Model (IGSM) code. This model was developed in coordination with the San Joaquin County (County) and DWR and was used to analyze several conjunctive use programs and projects. In 2001, the San Joaquin County IGSM model was converted to a DYNFLOW platform (a proprietary finite element groundwater flow model) and was used for the County’s Water Management Plan (CDM, 2008). The model originally simulated a period of October 1969 through September 1993 and was updated in 2007 for the Eastern San Joaquin Integrated Regional Water Management Plan (IRWMP) to simulate hydrologic conditions through September 2006. The proprietary nature of DYNFLOW makes the model not suitable to support subbasin analysis as part of GSP development per SGMA requirements.

With the award of Proposition 1’s Counties with Stressed Basins Grant, the determination was made to combine data from the older models into a new, local-scale model using DWR’s code that updated and replaced IGSM, called Integrated Water Flow Model (IWFM). IWFM is an open-source, finite element simulation code that supports triangular and quadrilateral elements (Dogrul et al., 2017a). It was specifically designated in GSP regulations as being supported by DWR for water budget development and SGMA compliance. It is also the code used for DWR’s California Central Valley Groundwater-Surface Water Simulation Model (C2VSim), the fine grid version of which is being refined and enhanced by DWR to support SGMA activities throughout the Central Valley at the regional scale (Brush et al., 2013). C2VSim was developed using the same methodology and source data as were ESJWRM’s datasets. To maintain consistency, ESJWRM relies on C2VSim for many of its datasets.

The IWFM Demand Calculator (IDC) is the stand-alone root zone component of IWFM that simulates land surface and root zone flow processes (Dogrul et al., 2017b). It calculates agricultural and urban water demands using inputs including climate conditions, soil parameters, and land use types and distribution.

It can be run separately or combined with IWFM. IDC data development and results in this documentation are included as part of all other IWFM datasets and results. The IDC major data pieces and draft results were initially presented in a February 1, 2018 Technical Memorandum (Appendix B).

At the October 26, 2016 Technical Review Committee meeting, the decision was made to keep the model domain the same as for the DYNFLOW model. The County’s DYNFLOW model included the ESJ Subbasin, as well as the Cosumnes Subbasin to the north and the Modesto Subbasin to the south. The ESJ Subbasin is the primary model area and the secondary model area includes the Cosumnes and Modesto Subbasins.

The physical model boundaries are included in Table 2 and shown in Figure 4.

Table 2: Physical Model Boundaries
Boundary Entire Model Primary Model Area
(ESJ Subbasin)
North Cosumnes River Dry Creek and County Boundary
(including Mokelumne River)
East Sierra Nevada Foothills Sierra Nevada Foothills
South Tuolumne River Stanislaus River
West San Joaquin River San Joaquin River
ATTACHMENT 2
San Joaquin County 2-4 Woodard & Curran
ESJWRM Report August 2018

2. MODEL DEVELOPMENT
This section presents the source and analysis of input data used in the development of ESJWRM. This includes spatial and temporal information for hydrologic and hydrogeologic data sets included in the model, as well as physical parameters and assumptions.

2.1 Model Input Data
The historical ESJWRM simulates water years 1995 through 2015 (October 1, 1994 through September 30, 2015). All data and computations are performed on a monthly time step. IWFM model files and corresponding major data sources and report sections are referenced below in Table 3.

Table 3: ESJWRM Major Model Data
Major Data
Category Minor Data Category Data Source Report Section Hydrogeological
Data
Geologic Stratification C2VSim 2.9
Aquifer Parameters USGS Texture Model 4.7
Stream Data
Stream Configuration C2VSim & San Joaquin
County 2.3
Stream Inflow USGS & USACE Stream
Gauges 2.3
Calibration Gauges USGS & CDEC Stream
Gauges 4.3
Hydrological Data Precipitation PRISM & CalSIMETAW 2.4
Agricultural Water
Demand
Land Use
DWR
CropScape
Land IQ
Ag Commissioner’s Report
Local Information

2.6 Evapotranspiration
C2VSim
METRIC
Local Information

2.7 Soil Properties SSURGO & STATSGO2 2.5
Urban Water
Demand
Population U.S. Census Bureau &
Local Information 3.2
Per Capita Water Use Local Information
(UWMPs) 3.2
Water Supply
Groundwater Pumping Local Information 3.3.2
Surface Water
Deliveries Local Information 3.3.1
Other
Boundary Conditions C2VSim & Local
Information 2.11
Initial Conditions C2VSim 2.12
Small Watersheds C2VSim 2.10
Calibration Wells DWR & Local Information 4.5
ATTACHMENT 2
San Joaquin County 2-5 Woodard & Curran
ESJWRM Report August 2018
The hydrologic period used to build the model data files was water years 1969 through 2018 (October 1, 1968 through September 30, 2018). This allows for future work to use a longer model run time using actual historical rainfall and stream inflow records.

2.2 Model Grid and Reporting Units
The finite element grid was developed using Aquaveo’s Groundwater Modeling System (GMS) software.

The grid includes quadrilateral and triangular elements based on selected input lines and control points.

Features included in the development of the model grid are shown in Figure 5 and included:
• Groundwater subbasin boundaries
• Hydrologic and hydrogeologic features (i.e., major and minor streams, reservoirs/lakes, and outcroppings)
• City spheres of influence boundaries
• ESJ Subbasin GSA boundaries
• County boundaries
• Subsurface flow patterns
• Other boundaries
The model grid contains 16,054 elements and 15,302 nodes with an average element area of 76.5 acres (Figure 6). The average node spacing is 0.37 miles overall, ranging from about 0.28 miles near hydrologic features to 0.42 miles in other areas. There was a 0.75-mile buffer included around the streams to transition from the finer to coarser node spacing. Primary objectives during grid development were to maintain a manageable number of elements and nodes, to optimize resolution for data analysis, to contain a finer resolution along rivers to allow for better simulation of stream-aquifer interaction, to optimize the model run time, and to streamline model output.

The model elements are grouped into 20 model subregions that are used to organize input data for the model and report standard model output water budgets (Figure 7). Subregion borders were delineated using boundaries including city spheres of influence, water agencies, subbasin, and county lines. These subregions are aggregated into 8 larger units (model subareas), which are the primary units to present results and are used for basin-scale planning (Figure 8). ESJ Subbasin, the primary model area, is made up of 6 subareas and 18 subregions or a total of 772,377 acres (about 1,207 square miles). The entire ESJWRM area covers 1,228,194 acres (about 1,919 square miles). A description of model subregions, including the subarea they are part of and the number of model elements they contain, is in Table 4.

Table 4: Model Subregions and Subareas
Subregion
Number Subregion Name Subarea Name and Number
Number of
Elements
1 North Delta North Delta
Subarea (#1) 872
2 Woodbridge North Subarea
(#2)
485
3 Lodi 104
4 North San Joaquin 1,969
ATTACHMENT 2
San Joaquin County 2-6 Woodard & Curran
ESJWRM Report August 2018
Subregion
Number Subregion Name Subarea Name and Number
Number of
Elements
5 Calaveras Calaveras
Subarea (#3) 664
6 Stockton
Central
Subarea (#4)
1,074
7 Stockton East 1,314
8 Central San Joaquin 929
9 Lathrop
South Subarea
(#5)
119
10 Manteca 224
11 South San Joaquin East 632
12 Escalon 33
13 Oakdale West 128
14 South Delta 254
15 South San Joaquin West 74
16 Ripon 86
17 Stanislaus Stanislaus
Subarea (#6)
1,312
18 Oakdale East 332
19 Cosumnes Cosumnes
Subarea (#7) 2,378
20 Modesto Modesto
Subarea (#8) 3,071

2.3 Stream Configuration and Stream Inflow
The model hydrology is represented by 25 model stream reaches, which are largely defined to start and/or end at confluences. Major streams include Cosumnes River, Dry Creek, Mokelumne River, Bear Creek, Calaveras River, Stanislaus River, Tuolumne River, and San Joaquin River (Figure 9). Many of these streams route water along connecting sloughs and canals, including Pixley Slough, Mosher Creek, Potter Creek, Mormon Slough, and Diverting Canal. As described in Section 2.2, the model grid was designed to include other hydrologic features such as major reservoirs or other important streams that may be simulated in ESJWRM in the future. Hydrologic features used during grid development (i.e., reservoirs and minor streams) include Camanche Reservoir, Duck Creek, Farmington Flood Control Basin, French Camp Slough, Little Johns Creek, Lone Tree Creek, Modesto Reservoir, Tracy Lakes, and Woodward Reservoir (Figure 5 and Figure 9). These hydrologic features represent important drainage and conveyance water courses in the model, while the model streams interactively simulate flows and stream-aquifer interaction at every model stream node.

The streams and creeks are represented in the model by 1674 stream nodes on a quarter-mile interval.

The number of stream nodes and their refined resolution provide increased accuracy when depicting stream-groundwater interaction. Physical characteristics, including the stream invert elevation, channel width, and a stream flow rating table, were obtained from the closest C2VSim stream nodes and United States Geological Survey (USGS) Digital Elevations Models (DEM).

Time series of stream inflow data is available from 7 USGS and the United States Army Corps of Engineers (USACE) gauging stations. This data is consistent with C2VSim streamflow data (Brush, 2013). A table of stream input data and a map of available stream gauge locations may be found in Table 5 and Figure 9.

ATTACHMENT 2
San Joaquin County 2-7 Woodard & Curran
ESJWRM Report August 2018
There was not sufficient data available for Bear Creek to generate a full time series record and it is only receiving runoff and/or drainage from nearby model elements.

Table 5: Summary of ESJWRM Stream Inflow Data
Stream Stream
Node Source Gauge Name Period of Record
Average
Annual
Streamflow
(acre-feet)
Cosumnes
River 1 USGS
USGS 11335000:

Cosumnes River at
Michigan Bar, CA
October 1907 to
present/ongoing 365,000
Dry Creek 140
USGS
Estimated in C2VSim by
correlation with USGS
11329500: Dry Creek near
Galt, CA
Not continuous
October 1926 to
December 1997
25,000
USGS
Estimated in C2VSim by
correlation with USGS
11335000: Cosumnes
River at Michigan Bar, CA
Used October 1987 to
September 1995 and
January 1998 to
present/ongoing
Mokelumne
River 290 USGS
USGS 11323500:

Mokelumne River below
Camanche Dam, CA
October 1904 to
present/ongoing 525,000
Calaveras
River 758
USGS
USGS 11308900: Calaveras
River below New Hogan
Dam near Valley Springs,
CA
February 1961 to
September 1990
151,000
USACE New Hogan Dam releases October 1990 to
present/ongoing
Stanislaus
River 1033 USGS
USGS 11302000:

Stanislaus River below
Goodwin Dam near
Knights Ferry, CA
February 1957 to
present/ongoing 575,000
Tuolumne
River 1248 USGS
USGS 11289650:

Tuolumne River below
Lagrange Dam near
Lagrange, CA
October 1970 to
present/ongoing 835,000
San Joaquin
River 1497 USGS
USGS 11303500: San
Joaquin River near
Vernalis, CA
October 1923 to
present/ongoing 3,089,000
ESJWRM also specifies how water routes at forks in the rivers. Ten percent of Bear Creek flows through Pixley Slough before returning to Bear Creek, while 90% continues in Bear Creek. Eighty percent of Calaveras River flows through Mormon Slough and the Diverting Canal before returning to Calaveras River, while 20% continues in Calaveras River.

ATTACHMENT 2
San Joaquin County 2-8 Woodard & Curran
ESJWRM Report August 2018

2.4 Precipitation
Rainfall data for the model area is derived from the PRISM (Precipitation-Elevation Regressions on Independent Slopes Model) database used in the DWR’s CALSIMETAW (California Simulation of Evapotranspiration of Applied Water) model. The database contains daily precipitation data from October 1, 1921 on a 4-kilometer grid throughout the model area. ESJWRM has monthly rainfall data defined for every model element in order to preserve the spatial distribution of the monthly rainfall. Each of the model elements was mapped to the nearest of 364 available PRISM reference nodes, uniformly distributed across the model domain. The resulting average annual precipitation is shown in Figure 10.

Figure 11 shows the annual rainfall in the model area and the cumulative departure from mean, which is an indication of long-term rainfall trends in the area. The minimum precipitation during the simulation period was in water year 2007 with 8.0 inches, while the maximum occurred in water year 1998 with 28.5 inches. The average precipitation was 15.1 inches, with 9 above average and 12 below average simulation years.

2.5 Root Zone Soil Parameters
The soil properties specified in the model are field capacity, wilting point, total porosity, saturated hydraulic conductivity, and pore size distribution index (PSDI). A recent update to IWFM added the capability to specify a separate saturated hydraulic conductivity for areas covered by rice or wetlands, which prevents the overestimation of deep percolation during periods of ponded water. All the soil properties are used to determine the soil types and characteristics of each model element.

DWR’s IWFM Soil Data Builder (DWR, 2017) was used in conjunction with the United States Department of Agriculture (USDA) Soil Survey Geographic Database (SSURGO) (USDA, 2017a) soil data to determine the five soil properties for each model element. The IWFM Soil Data Builder extracts the SSURGO data relevant to the model area (in this case, 6 counties) and associates it with each grid element. For ESJWRM elements where SSURGO data was incomplete, USDA’s Digital General Soil Map of the United States (STATSGO2) data were used instead (USDA, 2017b). In total, a little over 3,500 elements (about 22% of all elements) used STATSGO2 data for at least one of the parameters. Editing of soil parameters is a standard part of IDC calibration and the final soil parameter values and their spatial distributions are discussed and shown in figures in Section 4.2.

Model elements are associated with the four hydrological soil groups according to their runoff potential and infiltration characteristics. ESJWRM elements with their corresponding hydrologic soil group are shown in Figure 12. The Natural Resource Conservation Service (NRCS) (USDA NRCS, 2009) defines these hydrological soil groups as follows:
• Group A – Soils in this group have low runoff potential when thoroughly wet. Water is transmitted freely through the soil. Group A soils typically have less than 10 percent clay and more than 90 percent sand or gravel and have gravel or sand textures. Some soils having loamy sand, sandy loam, loam or silt loam textures may be placed in this group if they are well aggregated, of low bulk density, or contain greater than 35 percent rock fragments. • Group B – Soils in this group have moderately low runoff potential when thoroughly wet. Water transmission through the soil is unimpeded. Group B soils typically have between 10 percent and 20 percent clay and 50 percent to 90 percent sand and have loamy sand or sandy loam textures.

ATTACHMENT 2
San Joaquin County 2-9 Woodard & Curran
ESJWRM Report August 2018
Some soils having loam, silt loam, silt, or sandy clay loam textures may be placed in this group if they are well aggregated, of low bulk density, or contain greater than 35 percent rock fragments. • Group C – Soils in this group have moderately high runoff potential when thoroughly wet. Water transmission through the soil is somewhat restricted. Group C soils typically have between 20 percent and 40 percent clay and less than 50 percent sand and have loam, silt loam, sandy clay loam, clay loam, and silty clay loam textures. Some soils having clay, silty clay, or sandy clay textures may be placed in this group if they are well aggregated, of low bulk density, or contain greater than 35 percent rock fragments.
• Group D – Soils in this group have high runoff potential when thoroughly wet. Water movement through the soil is restricted or very restricted. Group D soils typically have greater than 40 percent clay, less than 50 percent sand, and have clayey textures. In some areas, they also have high shrink-swell potential.

2.6 Land Use and Cropping Patterns
For the model to calculate water supply requirements, every model element needs to have land use defined for every year of the simulation. ESJWRM includes 23 irrigated crop categories and 4 general land use categories. All of the irrigated crop categories except for rice are simulated as non-ponded crops, meaning they are grown without standing water. Rice is simulated as both no decomposition (assumed 20% of total rice area) and flooded decomposition (assumed 80% of total rice area) to represent the current understanding of local growing practices. The general land use categoriesinclude urban landscape (e.g., residential areas, golf courses, and school fields), water surface (e.g., streams, lakes, and reservoirs), riparian vegetation (e.g., native vegetation located near surface water), and native vegetation. The irrigated crop categories were combined into 6 high-level groupings of crops with similar water use or irrigation practices. Table 6 lists the land use categories.

The crop categories are identical to those in C2VSim, except that ESJWRM breaks out almonds, cherries, pistachios, and walnuts as individual categories. This was done at the request of the Technical Review Committee based on the importance and amount of these crops in the ESJ Subbasin.

Spatial land use data was used to specify land use types and crop acreages for each model element for each year. The three major reference sources include DWR land use surveys, CropScape, and Land IQ. As crop categories were not consistent across all the land use data sources, individual mappings matched up each crop type to model land use category.

DWR conducts periodic land use surveys for each county that include over 70 different crop categories, as well as urban and native vegetation, for each parcel or field (DWR, 1993-2000). DWR land use surveys have high accuracy due to extensive ground truthing. For ESJWRM, the land use surveys by county were merged and assumed to represent water year 1995 in the model. The surveys used include:

1. San Joaquin County (1996)

2. Sacramento County (1993)

3. Amador County (1997)

4. Calaveras County (2000)

5. Stanislaus County (1996)
ATTACHMENT 2
San Joaquin County 2-10 Woodard & Curran
ESJWRM Report August 2018
Data for water years 2007 through 2015 are from the USDA’s remote sensing CropScape data (USDA NASS, 2007-2015). CropScape includes 256 land use categories that come from annual satellite imagery collected during the growing season on 30-meter by 30-meter pixels. Based on reports on the CropScape website, the level of accuracy for this data is about 85-97% for crop-specific land cover categories. Although this level of accuracy is relatively high, the accuracy varies depending on many factors, including the time of the satellite image, growing season timing, cloud cover, type of crop, and maturity state of the crop.

DWR retained Land IQ to develop a statewide assessment of agricultural land use in summer 2014. Land IQ used remote sensing methods to collect and process the data at the parcel scale, which was then ground truthed for a reported overall accuracy of 96.6% (DWR, 2014). In ESJWRM, this data was used as verification of CropScape 2014 data and, in some cases, as replacement or enhancement of the CropScape data. Land IQ did not include a native vegetation category, so any blank land was assumed to be native vegetation.

Table 6: Land Use Categories
Land Use Type Model Category Grouped Categories
Irrigated Crops
Almonds
Cherries
Citrus & Subtropical
Other Orchard
Pistachios
Walnuts
Fruit and Nut Trees
Vineyards Vineyards
Alfalfa
Pasture
Alfalfa and Irrigated
Pasture
Grain Grain
Corn
Cotton
Dry Beans
Field Crops
Safflower
Sugar Beets
Field Crops
Cucurbits
Onion & Garlic
Potatoes
Tomato Fresh
Tomato Processing
Truck Crops
Truck Crops
Rice Rice
Other Land Use
Urban Landscape
Water Surface
Riparian Vegetation
Native Vegetation
ATTACHMENT 2
San Joaquin County 2-11 Woodard & Curran
ESJWRM Report August 2018
Local data and knowledge was also utilized to refine and correct, when necessary, the cropping acreages developed based on the DWR land use surveys and CropScape years. To fill the gap between 1995 and 2007, all land use and crop categories were interpolated at the spatial resolution level of the model element. Thus, the geographic distribution of interpolated land use and cropping patterns are honored.

Consistent mappings were developed to link crop categories from the various data sources to model categories based on previous work done for C2VSim. Adjustments were made, as needed, at the element level to ensure that the land use and cropping pattern trends over time are reflective of local data. These adjustments were mostly based on local knowledge and information received from various entities, including irrigation districts, water districts, and municipalities.

Figure 13 and Figure 14 show the spatial distribution of the major land use categories in the ESJ Subbasin for 1995 and 2015. Figure 15 shows the annual trends of land use categories in the ESJ Subbasin.

Figure 16, Figure 17, and Figure 18 show the spatial distribution of the irrigated crops for 1995, 2014, and 2015. Figure 19a-19g show the annual cropping patterns, by high level categories, for the entire ESJ Subbasin and major model subareas.

Overall, land use trends from 1995 through 2015 show significant increases in total and irrigated agricultural acreage, with about 384,000 irrigated acres in ESJ Subbasin at the beginning of simulation and about 398,000 acres with agricultural production by 2015. This change from native to agricultural area brings additional stresses on the hydrological system, particularly as the majority of this increase comes from conversion to higher water permanent crops, particularly vineyards, almonds, and walnuts. This translates to a higher water requirement, largely provided either by groundwater or surface water, though changes in irrigation methods may mitigate some of the increased water need due to land use changes.

Not all the subareas show an increase in agricultural land; many remain relatively consistent through the entire simulation period. When there was a decrease in agricultural land, there was a compensating increase in urban land, indicating the expansion of urban areas.

2.7 Evapotranspiration
The crop evapotranspiration (ET) requirement is an important factor in agricultural demand estimation.

Every ESJWRM land use category (except for water surface) plus small-stream watersheds must have average monthly values used for the entire simulation. To allow for spatial variability within the model, ET rates are also defined by model subregion.

The ET values are based on a variety of sources, including locally-developed data for the SSJID and the OID Agricultural Water Management Plans (AWMPs) (SJJID, 2015; OID, 2016) and averages for DWR’s CIMIS (California Irrigation Management Information System) Zone 12 developed using the Mapping Evapotranspiration at High Resolution with Internalized Calibration (METRIC) methodology, which is a remote-sensing based technology to estimate crop actual ET. Based on discussions with locals (pers. comm. Jennifer Spaletta representing NSJWCD and Bryan Thoreson representing SSJID), deficit irrigation of vineyards was simulated in ESJWRM with reference to the growing season ET values in the Lodi area (Prichard).

In IWFM, ET represents the net vertical water flux from the land surface and root zone through the upper model boundary. Figure 20 shows the range in annual evapotranspiration rates from the various sources for the 27 categories. Final model ET depends on the model subregion, with SSJID and OID using their locally-developed ET rates and the remainder of the model using the METRIC data.

ATTACHMENT 2
San Joaquin County 2-12 Woodard & Curran
ESJWRM Report August 2018

2.8 Drainage
Surface water drainage (e.g., runoff from rainfall and excess applied water) for each model element is assigned to a stream node representing where the drainage ultimately flows to. These drainage patterns were delineated using the USGS Watershed Boundary Dataset for 12-digit hydrologic units, also called subwatersheds. Each 12-digit hydrologic unit located within the model boundaries was associated with the model stream node it ultimately drained into through both visual analysis as well as information provided on the subwatersheds. Elements falling within the hydrologic units were assigned to the model stream node indicating the ultimate surface water drainage direction. A total of 94 unique stream nodes receive surface water drainage in ESJWRM from 79 subwatersheds. Figure 21 shows these stream nodes and the subwatersheds mapped to the model elements.

2.9 Model Layering
The subsurface zone is characterized by four model layers (three freshwater aquifers and one saline aquifer) representing the different geology from the ground surface to the bedrock. A small portion of the southwestern part of the subbasin has a confining unit of Corcoran Clay. The layering extents and thicknesses are all consistent with C2VSim. Descriptions of each of the model layers are listed below, from top to bottom.
• Layer 1: Layer 1 represents the top unconfined portion of the aquifer. The ground surface elevation (GSE), or the top of Layer 1, comes from the USGS DEM at a resolution of 10 meters.

The bottom of Layer 1 is defined as the top of Corcoran Clay where the confining unit exists or else as the bottom of Layer 1 in C2VSim. The layer thickness is limited by the stream invert elevation and ranges from 34 to 966 feet. The GSE is shown in Figure 22 and thickness of Layer 1 is shown in Figure 23.
• Aquitard 1: Corcoran Clay (i.e., E Clay) separates Layers 1 and 2 in a small portion of the southwest corner of the model. The extent, thickness, and depth of the Corcoran Clay originated from the Central Valley Hydrologic Model (CVHM) Spatial Database. The depth to the Corcoran Clay, ranging from 20 to 280 feet below the GSE, is shown in Figure 24 and the thickness of the Corcoran Clay, ranging from 10 to 160 feet, is in Figure 25.
• Layer 2: Layer 2 represents the primary pumping layer and is beneath the confining layer where Corcoran Clay exists. Layer 2 is principally bounded on the top by the bottom of Layer 1 or the bottom of Corcoran Clay (where it exists) and on the bottom by Layer 2 in C2VSim. The thickness of Layer 2, ranging from 50 to 540 feet, is in Figure 26. • Layer 3: Layer 3 extends to the base of fresh water. Information used in developing the bottom of Layer 3 includes data from Steven Springhorn of DWR’s North Central Regional Office, Christopher Olvera of DWR’s South Central Regional Office, and Williamson et al. 1989. The thickness of Layer 3, ranging from 50 to 1,335 feet, is in Figure 27.
• Layer 4: Layer 4 consists of the saline water ranging from the base of fresh water to the base of continental deposits and is a current non-production zone. Information used in developing the bottom of Layer 4 includes Page’s 1974 Base and Thickness of the Post Eocene Continental Deposits in the Sacramento Valley and the thickness of the aquifer developed by Williamson et al. 1989. The thickness of Layer 4, ranging from 50 to 2,250 feet, is in Figure 28.

Cross sections of the model layering in various locations across the model extent can be seen in Figure 29a-29f.

ATTACHMENT 2
San Joaquin County 2-13 Woodard & Curran
ESJWRM Report August 2018

2.10 Small-Stream Watersheds
The inflow from the eastern boundary of the model (i.e., Sierra Nevada foothills) originates from both gauged and ungauged watersheds. The simulation of gauged watersheds (i.e., stream inflows into the model) was discussed in Section 2.3 and shown in Figure 9. The simulation of the ungauged watersheds is explained in this section.

Flow from ungauged small watersheds is estimated based on precipitation rates and characteristics assigned to each identified ungauged watershed. A portion of flow from the small watershed enters the model area as surface runoff and flows to simulated streams. The remaining small watershed inflow infiltrates to groundwater.

ESJWRM simulates the ungauged eastern inflow using 39 distinct small watersheds (Figure 30), consistent with those on the eastern boundary of C2VSim. These were delineated originally from the USGS Watershed Boundary Dataset.

All subsurface inflows from these small watersheds are routed to model Layer 1 along specified groundwater nodes (Figure 30), with a user-defined maximum percolation rate at each node. Excess flows that do not infiltrate to groundwater enter the simulated streams at user-specified locations (Figure 30) delineated using a similar methodology to the drainage pattern discussed above in Section 2.8. The hydrologic conditions of these small watersheds used to estimate the subsurface and surface flows are represented using site-specific parameters (e.g., precipitation, surface layer soil parameters, runoff coefficient) based on C2VSim.

2.11 Boundary Conditions
As discussed in the previous section, inflows along the eastern boundary are represented using small watersheds. Boundary conditions define the subsurface inflows from all other boundaries of the model (i.e., northern, western, and southern), as well as areas with known groundwater levels.

Time series general head boundary conditions representing groundwater levels outside of the model area were defined for 596 boundary nodes on the northern, western and southern limits (i.e., along Cosumnes, Mokelumne, San Joaquin, and Tuolumne Rivers). Groundwater flow at the model boundaries was quantified based on the groundwater gradient across the model boundary. The head inside the model area is simulated by ESJWRM and the head outside the model area is based on historical groundwater elevation data from DWR’s Water Data Library (WDL).

Additional groundwater boundary conditions were defined to simulate known groundwater elevationsfor the Sacramento-San Joaquin Delta and lakes or reservoirs (reservoir locations shown in Figure 5). ESJWRM specifies high groundwater levels at or near zero feet for 60 groundwater nodes representing the edges of the Sacramento-San Joaquin Delta. Using data available in C2VSim, seepage from Camanche Reservoir was represented by specifying the full time series of groundwater levels for the 270 groundwater nodes representing the reservoir. The other reservoirs in the model were not included in C2VSim, so did not have boundary conditions available to estimate reservoir seepage. Instead, Woodward Reservoirseepage is included as a stream diversion from Stanislaus River (see Section 3.3.1). Farmington Flood Control Basin is used primarily for flood control purposes. Any recharge is incidental to the operation of the dam and is currently not included in ESJWRM. Modesto Reservoir, as it is located outside of the focus area of ESJ Subbasin, was not simulated.

ATTACHMENT 2
San Joaquin County 2-14 Woodard & Curran
ESJWRM Report August 2018

2.12 Initial Conditions
Groundwater heads for each model node and each layer at the beginning of the simulation (i.e., October 1, 1994) were developed using the DWR’s WDL database and San Joaquin County’s database of historical groundwater monitoring. Over 1,100 wells with data for Fall 1993, Fall 1994, or Fall 1995 were compiled and interpolated to create a raster representing initial groundwater levels for each model groundwater node. Due to the lack of information on well perforation and even depth for many of the WDL and San Joaquin County monitoring locations, the groundwater heads for each model layer are assumed to all begin at the same value. This assumption means the model needs about a year for groundwater levels to stabilize, so model results focus on water years 1996 through 2015 (a 20-year period). The initial conditions for ESJWRM representing October 1, 1994 are shown in Figure 31.

ATTACHMENT 2
San Joaquin County 3-1 Woodard & Curran
ESJWRM Report August 2018

3. WATER SUPPLY AND DEMAND DATA
The following sections describe the data and methodology for the ESJWRM water demand and supply calculations. Agricultural and urban demand are calculated in the IDC portion of IWFM. Agricultural and urban supply are specified in IWFM’s groundwater pumping and surface water diversion data.

3.1 Agricultural Water Demand
Agricultural water demand is the amount of irrigation water that is required to satisfy the crops evapotranspiration requirement. The IWFM Demand Calculator or IDC is designed to estimate the agricultural water demand for each model element through consumptive use methodology. The IDC calculations rely on model input data for historical crop acreage, irrigation practices (e.g., return and reuse fractions, irrigation period), soil moisture requirements, effective rainfall (the portion of rainfall available for crop consumptive use), crop evapotranspiration, and localized soil parameters. This data was compiled, analyzed, synthesized, and processed for input in ESJWRM.

Precipitation, land use, evapotranspiration, and soil properties are discussed in the relevant sections in Chapter 2. Irrigation period, using data from C2VSim, defines irrigation as either on or off for each crop and each month of the model simulation period. These were vetted and revised as necessary by the Technical Review Committee to better represent local practices in the ESJWRM area. Most trees are assumed irrigated from April through October (with almonds and pistachios from February through October), vineyards from May through October, most field crops from May through September, and most truck crops from April through September. Crops with irrigation assumed year-round include citrus and subtropical trees, irrigated pasture, alfalfa, and onions and garlic. Fractions to represent return flow (i.e., irrigation flow following the model drainage pattern discussed in Section 2.8) and reuse (i.e., the fraction of applied irrigation water to be reused for irrigation) are from C2VSim and are defined by subregion. For all ESJWRM, agricultural lands are given a 1% return flow and 1% reuse factor and urban landscape areas are assumed to have 15% return flow and 0% reuse.

3.2 Urban Water Use
IDC calculates urban demand based on per capita water use, population, and the breakdown of indoor versus outdoor water use by month. Figure 32 shows the annual population trends for each urban center.

Figure 33 shows the annual per capita water use values of these urban centers used in the calculation of urban water demand.

Population and per capita water use for the major urban areas were largely provided directly by the urban areas or were obtained from the respective Urban Water Management Plans (UWMP). Additional annual population, including an estimate for rural urban areas, came from the United States Census Bureau and the California Department of Finance. Monthly per capita water use, commonly reported in gallons per capita per day (GPCD), was generally estimated for each urban entity using the annual population and monthly urban water use (provided by cities based on water delivery records). To estimate the urban water demand of rural domestic water areas, the average major urban area GPCD was combined with estimated rural population.

It was assumed that an annual average of 60% of urban water was used indoors and 40% was used outdoors. The monthly fractions entered into the model had the majority of urban water demand due to ATTACHMENT 2
San Joaquin County 3-2 Woodard & Curran
ESJWRM Report August 2018
indoor activities from November through March and up to a maximum of 60% of urban water used outdoors for the remainder of the year.

The indoor/outdoor breakdown received concurrence from the urban water providers who attended the Technical Review Committee meetings. Population and per capita water use data were reviewed by the major urban areas and confirmed at the meetings (pers. comm. Kathryn Garcia from Lodi, Andrew Richle from Lodi, Michael Bolzowski from Cal Water, Greg Gibson from Lathrop, and Elba Mijango from Manteca).

3.3 Water Supply Summary
Both the agricultural and urban demands estimated by IDC are primarily met through the IWFM representation of surface water diversions and groundwater pumping. Other sources of water simulated in IWFM to meet demand include precipitation and existing moisture in the soil.

3.3.1 Surface Water
Historical surface water diversions for the simulation period were compiled from a combination of sources discussed in more detail in Section 3.4, including gauge data, water rights reports, UWMPs, AWMPs, and other sources. Some diversions were estimated based on historical demands. A summary of diversions simulated in the model is provided in Table 7, 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).

The monthly data for all these diversions came from local agencies or C2VSim (Modesto Subbasin diversions and riparian diversions) as discussed in more detail in Section 3.4. Many diversions provide water across model subregions, so deliveries are assigned to a group of elementsrepresenting the delivery area. Diversions either are taken out of streams at specified model streams nodes or are imported into the model area (i.e., diversion location occurs upstream of stream inflow gauge). Figure 34 shows the stream nodes where diversions occurred.

Table 7: Summary of ESJWRM Surface Water Deliveries
ID Description Diversion
Location Delivery Area Use
Fraction Average
Annual
Diversion***
(acre-feet)
Data
RL* NL** Delivery Source
1 Mokelumne River
to Woodbridge ID
for Ag
Mokelumne
River at Lodi
Lake
Element group
representing
Woodbridge
Irrigation
District
Ag 30% 2% 68% 56,700 WID
2 Mokelumne River
to City of Lodi (by
agreement with
Woodbridge ID)
Mokelumne
River at Lodi
Lake
Lodi Sphere of
Influence Urban 3% 1% 96% 5,000 WID
ATTACHMENT 2
San Joaquin County 3-3 Woodard & Curran
ESJWRM Report August 2018
ID Description Diversion
Location Delivery Area Use
Fraction Average
Annual
Diversion***
(acre-feet)
Data
RL* NL** Delivery Source
3 Mokelumne River
to City of Stockton
for Delta Water
Supply Project (by
agreement with
Woodbridge ID)
Mokelumne
River at Lodi
Lake
Element group
representing
Stockton area
minus Cal Water
Urban 3% 1% 96% 5,400 WID
4 Mokelumne River
to Contra Costa
WD (by
agreement with
Woodbridge ID)
Mokelumne
River at Lodi
Lake
Export out of
model Urban 0% 0% 100% 2,000 (one year only) WID
5 Mokelumne River
to North San
Joaquin WCD For
Ag
Mokelumne
River between
Camanche
Reservoir and
Lodi Lake
Element group
representing
North San
Joaquin WCD
Ag 10% 2% 88% 2,200 NSJWCD
6 Calaveras River to
Bellota Pipeline to
Stockton East WD
WTP for M&I
Calaveras River
at split with
Mormon
Slough
Stockton Sphere
of Influence Urban 3% 1% 96% 15,800 SEWD
7 Calaveras River to
Calaveras County
WD for Ag
Import (outside
of ESJWRM)
Calaveras
Subregion
(Subregion 5)
Ag 9% 1% 90% 1,100 CCWD
8 Calaveras River to
Stockton East WD
for Ag
Calaveras River
at split with
Mormon
Slough
Element group
representing
Stockton East
Water District
agricultural
customers
Ag 40% 5% 55% 42,600 SEWD
9 Calaveras River to
Farmington
Groundwater
Recharge Program
Calaveras River
at split with
Mormon
Slough
Element group
representing
recharge
locations
Ag 100% 0% 0% 1,300 SEWD
10 San Joaquin River
at Empire Tract to
City of Stockton
for Delta Water
Supply Project
San Joaquin
River at Empire
Tract just after
junction with
Bear Creek
Element group
representing
Stockton area
minus Cal Water
Urban 3% 1% 96% 7,800 City of
Stockton
ATTACHMENT 2
San Joaquin County 3-4 Woodard & Curran
ESJWRM Report August 2018
ID Description Diversion
Location Delivery Area Use
Fraction Average
Annual
Diversion***
(acre-feet)
Data
RL* NL** Delivery Source
11 San Joaquin River
to North Delta
San Joaquin
River near
North Delta
Subregion
Element group
representing
North Delta
Ag 5% 1% 94% 107,000 Estimated
by model
12 San Joaquin River
to South Delta
San Joaquin
River near
South Delta
Subregion
Element group
representing
South Delta
Ag 5% 1% 94% 14,200 Estimated
by model
13 Farmington
Reservoir via
Lower Farmington
Canal to Peters
Pipeline to
Stockton East WD
WTP
Import (outside
of ESJWRM)
Stockton Sphere
of Influence Urban 3% 1% 96% 33,300 SEWD
14 Farmington
Reservoir via
Lower Farmington
Canal to Stockton
East WD for Ag
Import (outside
of ESJWRM)
Element group
representing
Stockton East
Water District
agricultural
customers
Ag 15% 2% 83% 5,300 SEWD
15 Farmington
Reservoir via Little
Johns Creek and
Lower Farmington
Canal to Central
San Joaquin WCD
for Ag
Import (outside
of ESJWRM)
Element group
representing
Central San
Joaquin WCD
Ag 28% 2% 70% 38,800 SEWD
16 Stanislaus River to
Farmington
Groundwater
Recharge Program
Import (outside
of ESJWRM)
Element group
representing
recharge
locations
Ag 100% 0% 0% 3,000 SEWD
17 Woodward
Reservoir to South
San Joaquin ID for
Ag
Import (outside
of ESJWRM)
Element group
representing
South San
Joaquin ID
minus Division 6
Ag 21% 6% 74% 195,300 SSJID
18 Stanislaus River at
Goodwin Dam to
Oakdale ID for Ag
Import (outside
of ESJWRM)
Element group
representing
Oakdale ID
Ag 16% 1% 83% 111,100 OID
ATTACHMENT 2
San Joaquin County 3-5 Woodard & Curran
ESJWRM Report August 2018
ID Description Diversion
Location Delivery Area Use
Fraction Average
Annual
Diversion***
(acre-feet)
Data
RL* NL** Delivery Source
19 Woodward
Reservoir Seepage
Import (outside
of ESJWRM)
Element group
representing
Woodward
Reservoir
Ag 100% 0% 0% 17,500 SSJID
20 Woodward
Reservoir to Nick
C. DeGroot WTP
to City of Manteca
for M&I
Import (outside
of ESJWRM)
Manteca Sphere
of Influence Urban 3% 1% 96% 6,300 AWMP/UWMP
21 Woodward
Reservoir to Nick
C. DeGroot WTP
to City of Escalon
for M&I
Import (outside
of ESJWRM)
Escalon Sphere
of Influence Urban 3% 1% 96% 0
AWMP/
UWMP
22 Woodward
Reservoir to Nick
C. DeGroot WTP
to City of Lathrop
for M&I
Import (outside
of ESJWRM)
Lathrop Sphere
of Influence Urban 3% 1% 96% 1,100 AWMP/UWMP
23 Woodward
Reservoir to Nick
C. DeGroot WTP
to City of Ripon
for M&I
Import (outside
of ESJWRM)
Ripon Sphere of
Influence Urban 3% 1% 96% 0
AWMP/
UWMP
24 Tuolumne River to
Modesto ID
Import (outside
of ESJWRM)
Element group
representing
Modesto ID
Ag 15% 3% 82% 307,600 C2VSim
25 Tuolumne River to
City of Modesto
(via Modesto ID)
Import (outside
of ESJWRM)
Element group
representing
City of Modesto
Urban 5% 1% 94% 30,600 C2VSim
26 Cosumnes River to
Riparian for Ag
Along
Cosumnes
River near
confluence
with
Mokelumne
River
Element group
representing
riparian
diverters
Ag 10% 2% 88% 4,300 C2VSim
27 Dry Creek to
Riparian for Ag
Approximately
midway along
Dry Creek
Element group
representing
riparian
diverters
Ag 10% 2% 88% 6,000 C2VSim
ATTACHMENT 2
San Joaquin County 3-6 Woodard & Curran
ESJWRM Report August 2018
ID Description Diversion
Location Delivery Area Use
Fraction Average
Annual
Diversion***
(acre-feet)
Data
RL* NL** Delivery Source
28 Mokelumne River
to Riparian for Ag
Approximately
midway along
Mokelumne
River
Element group
representing
riparian
diverters
Ag 10% 2% 88% 9,700 C2VSim
29 Calaveras River to
Riparian for Ag
Calaveras River
at split with
Mormon
Slough
Element group
representing
riparian
diverters
Ag 10% 2% 88% 20,400 C2VSim
30 Stanislaus River to
Riparian for Ag
Approximately
midway along
Stanislaus River
Element group
representing
riparian
diverters
Ag 15% 3% 82% 20,700 C2VSim
31 Tuolumne River to
Riparian for Ag
Approximately
midway along
Tuolumne River
Element group
representing
riparian
diverters
Ag 15% 3% 82% 2,500 C2VSim
32 San Joaquin River
to Riparian for Ag
San Joaquin
River near
confluence
with Tuolumne
River
Element group
representing
riparian
diverters
Ag 15% 3% 82% 6,200 C2VSim
33 Woodward
Reservoir to South
San Joaquin ID
Division 6 for Ag
Import (outside
of ESJWRM)
Element group
representing
South San
Joaquin ID
Division 6
Ag 15% 2% 83% 5,200 SSJID
*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)

3.3.2 Groundwater Pumping
Groundwater pumping within ESJWRM is separated into well- or element-based pumping. The former largely includes district-operated wells that feed into the surface water supply network, while the latter includes estimated private groundwater pumping.

District pumping (or well pumping) is specified monthly throughout the simulation period. Data was provided by local agencies and included well locations, depths and perforations, use (agricultural or urban) and historical monthly pumping records. Table 8 lists the number of wells by type and agency included in ESJWRM. Figure 35 shows all the district pumping wells (separated by agricultural and municipal wells) in ESJWRM.

ATTACHMENT 2
San Joaquin County 3-7 Woodard & Curran
ESJWRM Report August 2018
Table 8: Summary of ESJWRM Well Pumping
Agency
Number of
Urban
Pumping Wells
Number of
Agricultural
Pumping Wells
Average Annual
Urban Pumping
(acre-feet)
Average Annual
Agricultural Pumping
(acre-feet)
Cal Water 56 --- 9,600 0
Escalon 4 --- 1,400 0
Lathrop 6 --- 2,200 0
Linden County WD 4 --- 450 0
Lockeford CSD 4 --- 530 0
Lodi 29 --- 15,200 0
Manteca 15 31 9,500 1,300
Oakdale ID --- 24 0 5,800
Ripon 9 9 3,900 1,100
SEWD 5 --- 3,100 0
SSJID --- 28 0 5,200
Stockton 37 --- 9,300 0
Total Average Annual Pumping (acre-feet) 55,180 13,400
Private groundwater pumping quantities on an individual well basis are largely unknown, though aggregate estimates for private pumping are often included in planning documents (e.g., AWMPs, UWMPs, groundwater management plans). Therefore, private agricultural pumping in ESJWRM is estimated by IWFM on an element basis by assigning two virtual wells at the centroid of each model element. One well represents private agricultural pumping and one well represents rural residential pumping. These wells are used to calculate any additional pumping necessary to meet the agricultural and urban demand estimated by IDC for an element after district pumping and surface water has been distributed.

The perforation interval, which dictates the layers a simulated well extracts water from, were assigned separately to the agricultural and domestic (i.e., rural residential) wells. All agricultural wells were assumed to pump 40% from Layer 1 and 60% from Layer 2. Rural residential wells used a statistical analysis of perforation interval developed for C2VSim. Perforation interval data was compiled by DWR using data from the CASGEM and Online System for Well Completion Reports (OSWCR) databases. Simulated perforation intervals were assigned as the 5th and 95th percentiles of the well perforation interval data for each township/range block.

3.4 Water Supply Sources
This section provides a detailed description of the sources of water supply (both surface water and pumping) occurring in ESJWRM.

3.4.1 Delta Areas
The North Delta and South Delta Subregions (Subregion 1 and 14) are mostly assumed to cover the portion of the Sacramento-San Joaquin River Delta overlying the ESJ Subbasin. As discussed at the Technical Review Committee meetings, the majority of the agricultural water demand in these areas is known to be entirely served by surface water taken off the San Joaquin River. Therefore, almost all of the agricultural demand is assumed to be supplied by the San Joaquin River (Diversion #11 and #12 for North Delta and ATTACHMENT 2
San Joaquin County 3-8 Woodard & Curran
ESJWRM Report August 2018
South Delta, respectively). A small portion of the agricultural land is assumed to rely on groundwater via element pumping. All of the urban demand is supplied by small, private residential wells and is estimated in ESJWRM using element pumping.

Though Subregions 1 and 14 are assumed to represent the Delta, elements in Subregions 1 and 14 receive surface waterfrom other diversions unrelated to the assumed riparian Delta diversions. A portion of WID’s delivery area extends into Subregion 1 and is supplied by WID’s diversion off the Mokelumne River (Diversion #1) as discussed in Section 3.4.2. Portions of other riparian diversions discussed in Section

3.4.19 extend into Subregions 1 and 14, specifically Dry Creek (Diversion #27) in Subregion 1 and San Joaquin River (Diversion #32) in Subregion 14.

3.4.2 Woodbridge Irrigation District
WID receives water from the Mokelumne River, which is provided to its agricultural customers through a distribution canal network or is sold to nearby municipalities. Through agreements, Lodi and Stockton use some of WID’s surface water right beginning in water years 2013 and 2012, respectively (Diversion #2 and #3). In water year 2013, WID supplied Contra Costa Water District with a one-time transfer of 2,000 AF (acre-feet), represented by Diversion #4. Diversion #1 delivers water to the element group representing WID’s service area, which spans portions of Subregion 1, most of Subregion 2, part of Subregion 3, and a small area of Subregion 6. The scale of the ESJWRM element grid is not refined enough to simulate deliveries on the parcel scale, so model elements may include parcels which do not in actuality receive surface water from WID.

Some of the agricultural demand (largely native landscape) adjacent to streams is met by the riparian diversion from Mokelumne River (Diversion #28) as discussed in Section 3.4.19. All remaining agricultural demand is estimated in ESJWRM as element pumping. All urban demand is likewise element pumping.

3.4.3 City of Lodi
The City of Lodi purchases surface water from WID, which it takes from the Mokelumne River adjacent to the city. Diversion #2 supplies part of the urban demand beginning in water year 2013, with all of the previous demand being met exclusively by groundwater. 29 municipal wells are simulated in the model, with at least 3 becoming inactive during the simulation period. Since Lodi began receiving surface water, its supply mix has steadily decreased its reliance on groundwater, from 100% of the urban demand in water year 2012 to 55% of the demand in water year 2015, with its increase in surface water use.

The agricultural land surrounding the current city boundaries is supplied by either WID on the west or NSJWCD to the east. Though the agricultural demand in these areas is small, WID’s Diversion #1 or NSJWCD’s Diversion #5, along with the riparian diversion from Mokelumne River (Diversion #28) (see Section 3.4.19), are able to supply some of the agricultural demand adjacent to Lodi. The city’s wastewater treatment plant, located to the west of the city in Subregion #1, is surrounded by fields irrigated using recycled water from the treatment plant. Any additional agricultural or urban demand is estimated in ESJWRM as element pumping.

3.4.4 North San Joaquin Water Conservation District
NSJWCD receives water from the Mokelumne River, which is provided to its agricultural customers as Diversion #5. Historically, NSJWCD has not used its entire water right allotment and did not divert any water towards the end of the simulation (starting water year 2013).

ATTACHMENT 2
San Joaquin County 3-9 Woodard & Curran
ESJWRM Report August 2018
Some of the agricultural demand adjacent to water is met by the riparian diversions from Dry Creek (Diversion #27) and Mokelumne River (Diversion #28) (see Section 3.4.19). Any additional agricultural demand is estimated in ESJWRM as element pumping, while small domestic urban demand is met by element pumping.

3.4.5 Lockeford Community Services District
LCSD is located within ESJWRM Subregion 4 and is surrounded by agricultural land under NSJWCD. LCSD has 4 municipal pumping wells used to meet all the urban demand generated by its customers. Some of the agricultural demand is met by the riparian diversion from Mokelumne River (Diversion #28) (see Section 3.4.19), while the remaining is met by element pumping.

3.4.6 Calaveras County
Only a small portion of Calaveras County extends into the ESJ Subbasin and the land is mostly unirrigated or native vegetation with small residential pockets and some irrigated agricultural parcels. CCWD uses a small amount of Calaveras River water for agricultural demand in the ESJ Subbasin (Diversion #7).

Additional agricultural demand is met by the riparian diversion from Calaveras River (Diversion #29) (see Section 3.4.19) or element pumping. All the residential demand is met by element pumping.

3.4.7 Stockton Area
The Stockton area includes service areas of both the City of Stockton as well as Cal Water. San Joaquin County also manages water for several unincorporated areas in and around the city.

Both the City of Stockton and Cal Water purchase surface water for urban use from SEWD. The water originates from either the Calaveras or Stanislaus Rivers and is delivered to customers after treatment at the SEWD water treatment plant (Diversion #6 and Diversion #13). Additionally, Stockton began the Delta Water Supply Project in water year 2012 and built a water treatment plant, providing another source of surface water for the area from San Joaquin River at Empire Tract (Diversion #10) and Mokelumne River via agreement with WID (Diversion #3).

Stockton, Cal Water, and San Joaquin County maintain pumping wells for urban water use. Due to the scale of the element grid, many of the San Joaquin County areas were too small to be simulated separately from Stockton or Cal Water. Thus, San Joaquin County groundwater pumping is instead estimated by element pumping in ESJWRM. Stockton itself has 37 municipal wells in the area, though only about 14 are still active at the end of the simulation. Cal Water maintains a separate delivery area and operates 56 wells to meet urban demand, though only about 20 wells are active at the end of ESJWRM’s historical simulation. Due to the complexity of the water supply in the area, the supply mix for urban water use in ESJWRM is difficult to separate by agency, though for the entire area is, on average, 70% surface water and 30% groundwater pumping with the reliance on groundwater decreasing toward the end of simulation due to the construction of the Delta Water Supply Project.

One riparian diversion from Calaveras River (Diversion #29) provides water to areas adjacent to the river (see Section 3.4.19). Additional agricultural demand may be met by surface water from WID (Diversion #1) where it extends into the northern part of the Stockton area or SEWD (Diversion #8 and Diversion #14). Any additional agricultural demand occurring in the area is supplied by the estimated element pumping.

3.4.8 Stockton East Water District
ATTACHMENT 2
San Joaquin County 3-10 Woodard & Curran
ESJWRM Report August 2018
SEWD receives water from both Calaveras River (i.e., New Hogan Lake) and Stanislaus River (i.e., New Melones Lake) and sells water to its customers for both agricultural and municipal purposes. Agricultural water is delivered directly to customers scattered across the district area (model Subregions 6 and 7).

Municipal water, as discussed in Section 3.4.7, is routed to SEWD’s water treatment plant and is sold to the City of Stockton and Cal Water. Beginning in water year 2003, SEWD has operated groundwater recharge projects near its water treatment plant, utilizing water taken from both the Calaveras and Stanislaus Rivers.

In Table 7, SEWD’s two urban diversions are Diversion #6 and Diversion #13, the two agricultural diversions are Diversion #8 and Diversion #14, and the two diversions used for recharge are Diversion #9 and Diversion #16. One riparian diversion from Calaveras River (Diversion #29) provides water to areas adjacent to the river (see Section 3.4.19). SEWD operates 5 urban pumping wells in the vicinity of the water treatment plant that are mixed with the surface water for use in the Stockton area and are utilized rarely (only during water year 2015 during the simulation period of ESJWRM). Any additional agricultural or urban demand is met by element pumping.

3.4.9 Linden County Water District
LCWD is located within ESJWRM Subregion 7 and is surrounded by agricultural land under SEWD. Though it receives no surface water, LCWD has 4 municipal pumping wells to meet all the urban demand generated by its customers. By the end of the simulation, only 2 of the wells are still active.

3.4.10 Central San Joaquin Water Conservation District
CSJWCD receives water from Stanislaus River (i.e., New Melones Lake) (Diversion #15) that is used for agricultural demand in model Subregion 8. Any additional agricultural demand is estimated as element pumping by ESJWRM. All the private residential urban demand is likewise calculated as element pumping.

3.4.11 South San Joaquin Irrigation District
SSJID’s service area covers the agricultural lands around the cities of Manteca, Ripon, and Escalon. SSJID provides water to agricultural customers within the district using water from the Stanislaus River (taken out at Goodwin Dam) and then stored in Woodward Reservoir just east of the district’s area in Stanislaus County. Diversion #17 represents the agricultural diversion from Woodward Reservoir that is delivered to SSJID’s customers through its series of canals covering the district. Based on communication with SSJID, one portion of SSJID, Division 6 (formerly Division 9), began receiving more surface water beginning in water year 2011. An increase in surface water to Division 6 (near Ripon in Subregions 15 and 16) is simulated using Diversion #33. Diversion #19 represents the seepage from Woodward Reservoir as SSJID had monthly data estimating the groundwater recharge due to the reservoir. Diversion #30 simulates the riparian diverters along Stanislaus River (see Section 3.4.19).

SSJID maintains 28 agricultural wells located in and around the City of Manteca to augment their surface water supply. Any remaining agricultural demand in the district is met by element pumping estimated by ESJWRM.

The Nick C. DeGroot Water Treatment Plant located at Woodward Reservoir was constructed as part of the South County Water Supply Project through the collaboration of SSJID and the cities of Escalon, Lathrop, Manteca, and Tracy. Beginning in water year 2005, surface water deliveries from the treatment plant began to Lathrop, Manteca, and Tracy with Escalon deliveries to begin in the future (currently ATTACHMENT 2
San Joaquin County 3-11 Woodard & Curran
ESJWRM Report August 2018
Escalon’s allotment is sold to Tracy). Ripon potentially may be added to the project at a later point. These deliveries are simulated in ESJWRM as Diversion #20 (Manteca), #21 (Escalon), #22 (Lathrop), and #23 (Ripon). Urban demand in these areas in discussed further in the relevant sections below. Any private residential demand estimated by ESJWRM in SSJID is met by element pumping.

3.4.12 City of Lathrop
Lathrop has 6 municipal pumping wells, one of which was inactive for the entire simulation period but may come back online for future use. The city began receiving surface water from the South County Water Supply Project in water year 2005 (Diversion #22) and will receive a higher allotment in future phases of the project.

Since Lathrop began receiving surface water and normalized for the drought, its supply mix has steadily decreased its reliance on groundwater, from 100% of the urban demand in water year 2004 to an average of 74% of the demand after the South County Water Supply Project began (ranging from 53% to 92% at the peak of the drought).

The small amount of agricultural demand in the vicinity of Lathrop is supplied by element pumping in ESJWRM. Recycled water is utilized for some fodder crop irrigation and will be incorporated in baseline runs of the model.

3.4.13 City of Manteca
Manteca has 15 active municipal wells that provide water for urban use and 31 active agricultural wells used to irrigate city landscaping. Agricultural land near the city is irrigated by SSJID’s diversion from Stanislaus River (Diversion #17). Starting in water year 2005, Manteca began receiving water from the South County Water Supply Project (Diversion #20). Additional agricultural and urban demand not met by the mix of groundwater pumping and surface water supply is estimated in the model as element pumping.

Since Manteca began receiving surface water, its supply mix has steadily decreased its reliance on groundwater, from 100% of the urban demand before water year 2005 to an average of 62% of the demand after.

3.4.14 City of Ripon
Ripon has 9 municipal pumping wells, at least 5 of which remain active at the end of the historical simulation. In addition, Ripon has 3 agricultural wells used for the city’s non-potable system and 6 nonpotable wells owned by Nestle. The groundwater pumping is augmented by SSJID’s diversion from Stanislaus River (Diversion #17) used for agricultural land surrounding the city. The city is currently not receiving surface water for municipal use from the South County Water Supply project, but may pursue that possibility in the future (Diversion #23). Currently, all the urban demand is met by groundwater pumping.

Adjacent to the Stanislaus River, some elements are receiving water for agricultural purposes from the Stanislaus River riparian diversion (Diversion #30) as discussed in Section 3.4.19.

3.4.15 City of Escalon
Escalon has 4 municipal pumping wells, at least 3 of which remain active at the end of the simulation.

Starting in water year 2005, the city was eligible to receive water from the South County Water Supply Project (Diversion #21), but has yet to build the pipeline necessary to take advantage of the allotted ATTACHMENT 2
San Joaquin County 3-12 Woodard & Curran
ESJWRM Report August 2018
surface water. Currently, Escalon sells its allotment to the City of Tracy (located in San Joaquin County but outside of the ESJ Subbasin).

Agricultural land near the city is irrigated by SSJID’s diversion from Stanislaus River (Diversion #17) as discussed in Section 3.4.19. Any remaining agricultural demand is supplied using ESJWRM’s element pumping estimates.

3.4.16 Oakdale Irrigation District
OID takes surface water from Stanislaus River at Goodwin Dam that splits from SSJID’s water to go into OID’s distribution system to supply to agricultural users (Diversion #18). The district’s delivery area is spread between elements in ESJWRM Subregions 13, 18, and 20. Additional agricultural water comes from OID’s 24 wells spread around the district’s area.

3.4.17 Cosumnes Subbasin
As it is outside of the model focus area of ESJ Subbasin, the only diversions simulated in the Cosumnes Subbasin in ESJWRM are the riparian diversions from Cosumnes River (Diversion #26) and Dry Creek (Diversion #27) (see Section 3.4.19). Any additional agricultural or urban demands are met in the model by element pumping.

3.4.18 Modesto Subbasin
Three riparian diversions extend to elements in the Modesto Subbasin—Stanislaus River (Diversion #30), Tuolumne River (Diversion #31), and San Joaquin River (Diversion #32) (see Section 3.4.19). Additional agricultural surface water comes from the Tuolumne River to Modesto Irrigation District using data in C2VSim (Diversion #24). OID’s delivery area extends into the Modesto Subbasin and receives a portion of OID’s diversion off Stanislaus River (Diversion #18). Any remaining agricultural demand is supplied by ESJWRM-calculated element pumping.

Urban demand in the Modesto Subbasin is largely met using element pumping, except in the area of the City of Modesto, which receives surface water from Tuolumne River (via Modesto Irrigation District) in Diversion #25, with data from C2VSim.

3.4.19 Riparian Diverters
C2VSim includes surface water diversions to non-district riparian water users along simulated streams.

This information (diversion volumes, locations, and delivery areas) was pulled from C2VSim and used to simulate riparian diversions in ESJWRM. These diversions are from Cosumnes River (Diversion #26), Dry Creek (Diversion #27), Mokelumne River (Diversion #28), Calaveras River (Diversion #29), Stanislaus River (Diversion #30), Tuolumne River (Diversion #31), and San Joaquin River (Diversion #32). The riparian lands receiving these diversions are shown in Figure 36.

ATTACHMENT 2
San Joaquin County 4-1 Woodard & Curran
ESJWRM Report August 2018

4. MODEL CALIBRATION
The goals of model calibration are (1) to achieve a reasonable water budget for each component of the hydrologic cycle modeled (i.e., land and water use, soil moisture, stream flow, and groundwater) and (2) to maximize the agreement between simulated and observed groundwater levels at selected well locations and simulated and observed streamflow hydrographs at selected gauging stations. These objectives are achieved through verification of the model input data and adjustment of model parameters.

4.1 Model Calibration
Model calibration begins after data analysis and input data file development is completed. The calibration effort can be broken down into subsets that align with packages within the IWFM platform. As an integrated groundwater model, the results of each part of the simulation are dependent on one another.

The model calibration can be considered a systematic process that includes the following activities:
• Calibrate hydrologic demand
• Calibrate surface water features
• Calibrate overall water budgets for the model area
• Calibrate simulated groundwater levels to observed groundwater levels • Compare calibration performance with the calibration targets • Conduct additional refinements to model as necessary
ESJWRM was calibrated to local data and knowledge, surface water flows, groundwater hydrographs, and groundwater contours. The sources used to check model results include local knowledge (mainly gathered during Technical Review Committee meetings), AWMPs, UWMPs, other local planning efforts, measured groundwater levels and contours, and observed streamflow data.

Due to uncertainty in the initial conditions, a one year “ramp up” period is included to allow groundwater levels to stabilize. Thus, the model calibration period for the ESJWRM is October 1995 through September 2015 or water years 1996 through 2015 (20 years).

4.2 Calibration of the IDC and Root-Zone Parameters
The goal of the IDC calibration process is to determine reasonable urban and agricultural demand and develop the components of a balanced root zone budget. IDC calibration serves as the foundation of the IWFM calibration as demand estimated translates directly to groundwater pumping, which is the primary stress on the groundwater system. This part of the calibration effort focused primarily on refining individual budget items while maintaining reasonable root zone parameters.

The calibrated IDC was used to estimate monthly agricultural water demand at each model element during the model hydrologic period. To adjust agricultural demand, elemental root zone parameters, particularly the soil hydraulic conductivity and the pore size distribution index, were adjusted in accordance with the hydrologic soil group and subregion. Spatial representation of these calibrated parameters is shown in Figure 37 though Figure 41. The IDC model was calibrated to agricultural water use values reported by irrigation districts in their AWMPs and then checked against local data with input from irrigation district representatives and consultants (pers. comm. Doug Heberle from WID, Jennifer Spaletta representing ATTACHMENT 2
San Joaquin County 4-2 Woodard & Curran
ESJWRM Report August 2018
NSJWCD, Tom Flinn from NSJWCD, Peter Martin from CCWD, Cathy Lee from SEWD, Manuel Verduzco from SEWD, Sam Bologna from SSJID, Peter Rietkerk from SSJID, Bryan Thoreson representing SSJID, Emily Sheldon from OID, Eric Thorburn from OID, and Byron Clark representing OID). Figure 42a-42n show the agricultural water demand, unit agricultural water use, and unit evapotranspiration of applied water (ETAW) estimates by the total ESJ Subbasin area and major subareas. Differences in the charts between the subregion and subareas is due the differences in cropping patterns and evapotranspiration rates, which drive the estimation of agricultural demand. The difference between the two unit water use columns provide an indication of the efficiency of agricultural practices in the subregion or subarea.

Overall, the estimated agricultural demand reflects the same variability seen in irrigation practices and major crops from area to area within the ESJ Subbasin.

Figure 43a-43g show the model estimated annual urban demand for the total ESJ Subbasin area and subareas. Urban demand reflects the population and per capita water use defined for each urban area and estimated for the remaining rural residential areas.

4.3 Calibration of Surface Water Features
The ESJWRM simulates streamflow in 39 small watersheds and several major rivers and creeks across the model domain.

As discussed in Section 2.10, small watersheds are used to simulate inflows into the model from ungauged watersheds. The small watershed contributions are split between surface water runoff that enters the stream system, percolation that occurs during transport to the streams, and baseflow entering the groundwater system at the model boundary. Groundwater level hydrographs along the model boundary selected for groundwater level calibration (Section 4.5) were referenced to confirm and edit, as necessary, the various parameters of the small watersheds.

Streamflow calibration is primarily performed by comparing the simulated streamflow with local data from 11 stream gauges (Table 9 and Figure 44). Data for these gauges came from USGS or the California Data Exchange Center (CDEC). Two of these stream gauges (Mokelumne River below Camanche Dam and San Joaquin River near Vernalis) are duplicates of gauges used to estimate stream inflow into the model area and were not referenced for streamflow calibration and only verification of model setup.

Table 9: Summary of ESJWRM Stream Calibration Gauges
Stream Stream
Node Agency Gauge Name Period of Record
Cosumnes
River 98 USGS USGS 11336000: Cosumnes River at McConnell, CA October 1941 to
October 1982
Dry Creek 222 USGS USGS 11329500: Dry Creek near Galt,
CA
October 1926 to
December 1997
Mokelumne
River*
290 USGS USGS 11323500: Mokelumne River
below Camanche Dam, CA
October 1904 to
present/ongoing
Mokelumne
River 382 USGS USGS 11325500: Mokelumne River at Woodbridge, CA June 1924 to
present/ongoing
Mokelumne
River 501 USGS USGS 11336930: Mokelumne River at Andrus Island near Terminous, CA July 2006 to
present/ongoing
ATTACHMENT 2
San Joaquin County 4-3 Woodard & Curran
ESJWRM Report August 2018
Stream Stream
Node Agency Gauge Name Period of Record
Mormon
Slough 876 USACE CDEC MRS: Mormon Slough at Bellota December 1997 to present/ongoing Stanislaus
River 1067 DWR CDEC OBB: Stanislaus River at Orange Blossom Bridge January 1993 to
present/ongoing
Stanislaus
River 1186 USGS USGS 11303000: Stanislaus River at Ripon, CA October 1940 to
present/ongoing
Tuolumne
River 1382 USGS USGS 11290000: Tuolumne River at Modesto, CA April 1940 to
present/ongoing
San Joaquin
River*
1497 USGS USGS 11303500: San Joaquin River
near Vernalis, CA
October 1923 to
present/ongoing
San Joaquin
River 1597 USGS USGS 11304810: San Joaquin River below Garwood Bridge at Stockton, CA December 1995 to
present/ongoing
*Same as stream inflow gauge, so not used for calibration and included as verification of model setup Stream flow calibration included refinement of the stream bed hydraulic conductivity originally from C2VSim (Figure 45). Simulated stream flows were compared with observed records and exceedance charts were also used to check the model performance when simulating high and low flows at each gauge location. Calibration results for select stream gauges are included in Figure 46a-46j.

4.4 Calibration of Water Budgets
The aim of the calibration process is to ensure the accurate representation of the hydrologic characteristics of the groundwater basin, confirmed through the analysis of the resulting water budgets.

A water budget balances all supplies, demands, and any subsequent change in storage occurring within that specific portion of the hydrologic cycle. IWFM automatically outputs budgets at the subregion scale for processes involving groundwater, the surface layer, streams, the root zone, small watersheds, and the unsaturated zone. IWFM can output select budgets down to a single element or any specific grouping of elements.

During this step of the calibration process, model results are reviewed and summarized into monthly and annual (by water year) budgets. The most important budgets reviewed for calibration are the groundwater budget and the land and water use budget. After extensive budget analysis, key model datasets and parameters are adjusted, particularly groundwater aquifer parameters, to better match local budgets from AWMPs or other planning efforts. The ESJWRM water budget results are summarized in the following sections.

4.4.1 Land and Water Use Budget
The land and water use budget includes two different versions, agricultural and urban, and represents the balance of the IDC-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 Demand (either agricultural or urban)
o Surplus (if applicable)
ATTACHMENT 2
San Joaquin County 4-4 Woodard & Curran
ESJWRM Report August 2018
• Outflows:
o Groundwater pumping
o Surface water deliveries
o Shortage (if applicable)
The average annual water demand for the subbasin within the calibration period was 1.2 million acre-feet (MAF), consisting of approximately 1.1 MAF agricultural demand and 0.1 MAF urban demand. This demand was met by approximately an average annual of 0.50 MAF of surface water deliveries (0.45 MAF of agricultural and 0.05 MAF of urban deliveries) and was supplemented by approximately 0.69 MAF of groundwater production (0.62 MAF of agricultural and 0.07 MAF of urban pumping). The annual estimated land and water use budgetsfor the calibration period are presented in Figure 47a-47g and Figure 48a-48g, showing the agricultural and urban, respectively, demands and water supplies in the ESJ Subbasin and its component subareas. Due to uncertainties in the reported and estimated values of agricultural and urban water supplies, as well as respective estimates of the demands, there are some imbalances between the demand and supply values. These imbalances are shown as surplus or shortage and are typically less than 10% of the reported supplies, and within the margin of errors of the analysis.

4.4.2 Groundwater Budget
The primary components of the groundwater budget, corresponding to the major hydrologic processes affecting groundwater flow in the model area, are:
• Inflows:
o Deep percolation (from rainfall and excess irrigation applied water) o Gain from stream (or recharge due to stream seepage)
o Recharge (from other sources such as irrigation canal seepage and recharge ponds) o Boundary inflow (from outside the model area)
o Subsurface inflow (from adjacent subregions)
• Outflows:
o Groundwater pumping
o Loss to stream (or outflow to streams and rivers)
o Boundary outflow (to outside the model area)
o Subsurface outflow (to adjacent subregions)
• Change in groundwater storage (either an inflow or outflow) The groundwater budget consists of inflows to and outflows from the groundwater system. Figure 49a49g show the annual components of the groundwater budget, including cumulative change in groundwater storage for ESJ Subbasin. Primary components of the groundwater budget are as follows:
average annual groundwater pumping is estimated to be 0.70 MAF, which is offset by approximately 0.22 MAF of deep percolation from rainfall and applied water, net gain from stream of 0.15 MAF, recharge from conveyance and unlined canals of approximately 0.12 MAF, and a total net subsurface inflow of ATTACHMENT 2
San Joaquin County 4-5 Woodard & Curran
ESJWRM Report August 2018
approximately 0.16 MAF from neighboring subbasins and foothills. The cumulative change in groundwater storage is calculated from the change in groundwater storage. Due to inherent uncertainties in data and assumptions used in the model, approximations used in representing physical features in the aquifer system, and uncertainties in the model calibration, all budget components have some degree of uncertainty. A sensitivity analysis was performed to estimate the sensitivity of the model results to the changes in each of the key model parameters. Given the overall range of uncertainties, the long-term average annual depletion in groundwater storage in ESJ Subbasin during the model historical period is estimated to range between 24 to 70 TAF, with an average of approximately 47 TAF per year.

4.5 Groundwater Level Calibration
Like streamflow calibration, the goal of groundwater level calibration is to achieve reasonable agreement between the simulated and observed values (in this case, groundwater levels at calibration wells). Within the ESJWRM, over 3,000 wells were evaluated for developing groundwater observation locations to track ESJWRM’s calibration at both a regional and local scale. The records for these wells were obtained from San Joaquin County’s monitoring database, DWR’s CASGEM program, and local monitoring wells from the City of Lodi and Oakdale Irrigation District. The calibration wells were selected based on their period of record, spatial distribution across the model, representativeness of good indicators of model responses to the various stresses, availability of observation data, and trends of nearby wells. Though a working set of 160 wells was tentatively selected initially, this was narrowed to an ultimate set of 70 wells that are representative of the long-term conditions of groundwater levels both at a local and regional scale in ESJWRM. These 70 calibration wells are shown in Figure 50 with information tabulated in Appendix C.

Simulated groundwater levels are calibrated to observed levels through adjustments to hydrogeologic parameters or aquifer parameters including hydraulic conductivity, specific storage, and specific yield (discussed in Section 4.7). The goal of groundwater level calibration is to achieve the maximum agreement between simulated and observed groundwater elevations at calibration wells while maintaining reasonable values for aquifer parameters. The groundwater level calibration is performed in two stages:
• The initial calibration effort is focused on the regional scale to verify hydrogeological assumptions made during data development and confirm the accuracy of general groundwater flow vectors.

During this iteration, simulated groundwater elevation trends, flow directions, and groundwater gradients are compared to measured data. DWR’s groundwater level contours for spring and fall many years starting in the 2010s were used to evaluate ESJWRM’s groundwater contours from matching time periods. Figure 51a-51d show the resulting ESJWRM groundwater level elevations (average of the top 2 layers of the model where most of the pumping in the subbasin occurs) compared to DWR contours for 4 different seasons and years: Spring 2011, Fall 2013, Spring 2015, and Fall 2015. Fall 2015 also represents the end of simulation groundwater levels. • The second stage of calibration of groundwater levels is to compare the simulated and observed groundwater level at each calibration well. This comparison provides information on the overall model performance during the simulation period. The simulated groundwater elevations at the 70 calibration wells were compared with corresponding observed values for concurrence in longterm trends as well as seasonal fluctuations.

Discussed further in the next section (Section 4.6), the results of the groundwater level calibration indicate that the ESJWRM reasonably simulates the long-term hydrologic responses under various hydrologic conditions. Figure 52a-52r show a selection of calibration wells (1 representing each ESJ Subbasin model ATTACHMENT 2
San Joaquin County 4-6 Woodard & Curran
ESJWRM Report August 2018
subregion or 18 wells) with their resulting groundwater level hydrographs. All 70 calibration well hydrographs are included in Appendix C.

4.6 Measurement of Calibration Status
The ESJWRM calibration status was measured using two metrics: the groundwater level trend and the relationship between simulated and observed groundwater levels. The statistics were evaluated to meet the American Standard Testing Method (ASTM) standard. In addition to quantifiable metrics, the ESJWRM calibration was evaluated by generating reasonable regional groundwater flow directions and producing realistic water budgets.

The “Standard Guide for Calibrating a Groundwater Flow Model Application” (ASTM D5981) states that “the acceptable residual should be a small fraction of the head difference between the highest and lowest heads across the site.” The residual is defined as the simulated head minus the observed head. An analysis of all calibration water levels within the model indicated the presence of 200+ feet of water level changes.

Using 10 percent as the “small fraction”, the acceptable residual level would be 20 feet. Calibration goals for the groundwater level residuals were set such that no more than 10 percent of the observed groundwater levels would exceed the acceptable residual level of 20 feet. • 75% of observed groundwater levels are within +/- 10 feet of its respective simulated values • 97% of observed groundwater levels are within +/- 20 feet of its respective simulated values • 99% of observed groundwater levels are within +/- 30 feet of its respective simulated values The residual histogram for the ESJ Subbasin is shown in Figure 53. Additionally, a scatter plot of simulated versus observed values is shown in Figure 54.

4.7 Final Calibration Parameters
The initial aquifer parameters for the ESJWRM came from DWR’s texture model values extracted to C2VSim coarse grid nodes. These coarse grid nodes formed a parametric grid covering the model area and reflected the scale at which parameters were adjusted throughout the calibration process. The grid was slightly modified to cover the entire ESJWRM model along the boundaries and additional nodes were added or moved within areas of the model to provide better control (Figure 55). The parameters resulting from the calibration process are listed in Table 10.

Table 10: Range of Aquifer Parameter Values
Stream Layer 1 Layer 2 Layer 3 Layer 4
Horizontal Hydraulic
Conductivity (ft/day) 11.5 – 72.7 6.4 – 44.8 1.1 – 4.6 1.8 – 5.2 Vertical Hydraulic
Conductivity (ft/day) 0.005 – 0.14 0.004 – 0.07 0.004 – 0.05 0.004 – 0.15 Corcoran Clay Vertical
Hydraulic Conductivity
(ft/day)

3.6 x 10-4 –

1.5 x 10-3

3.6 x 10-4 –

1.5 x 10-3

3.6 x 10-4 –

1.5 x 10-3

3.6 x 10-4 –

1.5 x 10-3
Specific Storage
(unitless)

8.55 x 10-5 –

1.57 x 10-4

4.18 x 10-6 –

1.97 x 10-4

4.21 x 10-6 –

2.05 x 10-4

2.53 x 10-5 –

1.75 x 10-4
Specific Yield (unitless) 0.04 - 0.10 0.04 – 0.09 0.04 – 0.09 0.05 – 0.09 ATTACHMENT 2
San Joaquin County 4-7 Woodard & Curran
ESJWRM Report August 2018
Horizontal Hydraulic Conductivity – The hydraulic conductivity (KH) in the ESJWRM varies across the horizontal direction and across model layers. The fully calibrated values remain descriptive of the initial hydrogeologic analysis, range from 1.1 ft/day to 72.7 ft/day, and the spatial distribution is represented in Figure 56 through Figure 58.

Vertical Hydraulic Conductivity – Primarily a constraining factor across the Corcoran Clay in the small portion of the model underlain by it, the Vertical Hydraulic Conductivity (KV) facilitates the separation between the unconfined and confined aquifers within the ESJWRM. The KV values of the Corcoran aquitard is found to be less than one one-thousandth of the horizontal conductivity of the surrounding aquifer systems. For those parts of ESJWRM without Corcoran Clay, the KV controls the flow of groundwater between the materials making up the different modeled aquifer layers.

Specific Storage – Specific Storage (SS) is used to represent the available storage at nodes in a confined aquifer, where the hydraulic head is above the top of the aquifer. Specific Storage is the unit volume of water released or taken into storage per unit change in head. Calibrated specific storage values range from 4.18 x 10-6to 2.05 x 10-4, as shown in Figure 59 through Figure 61.

Specific Yield – Specific Yield (SY) is representative of the available storage in an unconfined aquifer and defined as the unit volume of volume released from the aquifer per unit change in head due to gravity.

Calibrated specific storage values range from 0.04 to 0.10 and are shown in Figure 62 through Figure 64.

4.8 Sensitivity Analysis
Sensitivity analysis is an important step in the model development process. It is defined as “the study of distribution of dependent variables (e.g., groundwater elevations in a groundwater model) in response to changes in the distribution of independent variables, initial conditions, boundary conditions, and physical parameters” (AWWA, 2001). In general, a sensitivity analysis of an integrated groundwater and surface water model is performed for the following purposes:
• To test the robustness and stability of the model by establishing tolerance within which the model parameters can vary without significantly changing the model results; • To understand the impact of inaccuracies in input data on model results (e.g., how model results can change because of a 10% error in the estimation of agricultural pumping); and • To develop an understanding of the relative sensitivity of the components of the hydrologic cycle and data, so that an effective data collection and monitoring plan can be developed.

A sensitivity analysis was performed using the ESJWRM to assess the sensitivity of model results to specific model parameters and input data. Two different metrics were selected to measure the sensitivity of the ESJWRM. A sensitivity metric is a single number derived from the ESJWRM results and has a unique value for each model run corresponding to a given set of data or parameter value. The sensitivity metrics used here:
• Average groundwater elevation in the study areas, and • Average root mean square (RMS) error aggregated from selected calibration wells.

Average groundwater elevation in the study areas is defined as a three-way average of simulated groundwater elevations at model nodes. The average is taken over the model layers, model nodes, and time.

ATTACHMENT 2
San Joaquin County 4-8 Woodard & Curran
ESJWRM Report August 2018
This can be mathematically expressed by:

𝐻̅ =
1 𝑀
∑ 𝐻𝑘
𝑀
𝐾=1
Such that,
𝐻𝑘 =
1 𝑁
∑[
1 𝐿
∑ℎ𝑗
𝐿
𝑗=1
]
𝑖
𝑘 𝑁
𝑖=1
Where,
M total number of simulation time steps,
Hk average head in the model area at k-th time step,
N number of model nodes,
L number of model layers in aquifer,
Hj groundwater elevation at layer j, and
i, j, k are indices for node, layer, and time, respectively.

The average RMS error at selected calibration wells is defined as the average of individual RMS error at each calibration well. The RMS error at a calibration well is defined as follows:

𝑅𝑀𝑆𝑤 = √{
1 𝑁
∑[ℎ𝑘,𝑤
0 − ℎ𝑘,𝑤𝑠
]
2 𝑁0
𝑘=1
}
where,
N0 is the number of observations at well k,
ℎ𝑘,𝑤
0 is the observed groundwater elevation at time step k, at well w, ℎ𝑘,𝑤
𝑠
is the simulated groundwater elevation at time step k, at well w.

4.8.1 Sensitivity Analysis Results
Adjustments of aquifer parameters, and the analysis the resulting groundwater head, was performed at all groundwater nodes within the model domain. Similarly, streambed conductance was analyzed at all model stream nodes. Sensitivity analyses were performed for the ESJWRM for the following parameters with results discussed below.

Horizontal Hydraulic Conductivity – The sensitivity of the ESJWRM to changes in hydraulic conductivity are presented in Figure 65 and Figure 66. Reduction of hydraulic conductivity to one-fourth of the calibrated value results in 10.13 feet higher groundwater levels in the model, whereas increases to hydraulic conductivity decrease the average groundwater levels by 2.05 feet. Changes to horizontal hydraulic conductivity have small impacts to RMS values.

ATTACHMENT 2
San Joaquin County 4-9 Woodard & Curran
ESJWRM Report August 2018
Vertical Hydraulic Conductivity – The sensitivity of the ESJWRM to changes in vertical hydraulic conductivity are presented in Figure 67 and Figure 68. Reduction of this parameter to one-fourth of the calibrated value results in 10.34 feet higher groundwater levels in the model, whereas increases to the vertical hydraulic conductivity decrease the average groundwater levels by 4.80 feet. Changes to vertical hydraulic conductivity have very little impact on RMS values.

Specific Storage – The sensitivity of the ESJWRM to changes in specific storage are presented in Figure 69 and Figure 70. Reduction of specific storage to one-fourth of the calibrated value results in approximately

12.64 feet higher groundwater levels in the model, whereas increases to specific storage decrease the average groundwater levels by 1.49 feet. Changes to specific storage have very little impact on RMS values.

Specific Yield – The sensitivity of the ESJWRM to changes in specific yield are presented in Figure 71 and Figure 72. Reduction of specific yield to one-fourth of the calibrated value results in 11.67 feet higher groundwater levels in the model and increases to specific yield increase the average groundwater levels by 1.82 feet. Changes to specific yield have slight impacts to RMS values.

Streambed Conductance – The sensitivity of the ESJWRM to changes in streambed conductance are presented in Figure 73 and Figure 74. Reduction of conductance to one-fourth of the calibrated value results in 8.09 feet higher groundwater levels in the model, whereas increases to conductance decrease the average groundwater levels by 5.09 feet. Changes to streambed conductance have slight impacts to RMS values.

The results of the sensitivity analysis for the ESJWRM indicate that the model is a stable model and the system responds in the expected manner because of changes in aquifer parameters and other input data.

ATTACHMENT 2
San Joaquin County 5-1 Woodard & Curran
ESJWRM Report August 2018

5. CONCLUSIONS AND RECOMMENDATIONS
The ESJWRM, in its current state, is a robust, comprehensive, defensible and well-established model for assessing the water resources in the ESJ Subbasin under historical and projected conditions. The following recommendations are to be considered for further refinements and enhancements of the model:
• Continue engagement with local groundwater users and managers. Continue working with local agencies and groundwater users in ESJ Subbasin to further understand the local operations of the groundwater system and improve representation of groundwater users in the ESJWRM. • Refinement of boundary flows. The current boundary flows at the northern, western, and southern boundaries of the model area are based on an older version of the C2VSim with adjustments made based on initial groundwater levels assumed for the beginning of the model (October 1994). DWR is currently in the process of updating the C2VSIm model. Once the latest fine grid version (C2VSim-2015) is publicly available, boundary flows for the ESJ model area should be verified and updated, as necessary.
• Enhance variability of potential evapotranspiration. The current version of the IDC used for estimation of the consumptive use of crops in the ESJWRM uses monthly potential ET values that are the same for all years during the model period. Given that there may be annual variability in the potential ET data with possible effects on the annual estimation of crop water demand, it is recommended to use more detailed data with temporal variability to develop a full time series of ET values for use in the model.
• Refine surface water deliveries in Cosumnes and Modesto Subbasins. The surface water deliveries in the Cosumnes and Modesto Subbasins are currently at the subregion level and do not have the detailed spatial resolution of other areas within the ESJ Subbasin. This data may need to be verified and updated as modeling efforts in those subbasins progress to meet the requirements of SGMA.
• Update C2VSim based on ESJWRM. The fine grid version of C2VSim was developed by the DWR to evaluate the integrated surface water and groundwater conditions at a regional scale; whereas, the ESJWRM is capable of evaluation at the local scale. To increase the accuracy of regional groundwater conditions in the fine grid C2VSim, the County is encouraged to work with DWR to provide data and information for further refinement and update of C2VSim in the ESJWRM area. • Develop model update schedule. In order to keep the ESJWRM up-to-date and current for analysis of water resources and especially for supporting SGMA implementation, it is recommended that the model be updated every 3 to 5 years. A possible update schedule can be kept consistent with the GSP updates, with a lead time of 2 to 3 years relative to the GSP update schedule.

ATTACHMENT 2
San Joaquin County 6-1 Woodard & Curran
ESJWRM Report August 2018

6. REFERENCES
American Water Works Association (AWWA), 2001. Water Resources Planning. Manual of Water Supply Practices (M50) Second Edition.

ASTM D5981. Standard Guide for Calibrating a Groundwater Flow Model Application.

Brush, Charles F, 2013. Historical Rim Inflows, Surface Water Diversions and Bypass Flows for the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim), Version 3.02-CG. http://baydeltaoffice.water.ca.gov/modeling/hydrology/C2VSim/download/C2VSim_ Historical_Flows_Diversions_Final.pdf.

Brush, Charles F, Emin C Dogrul, and Tariq N Kadir, 2013. Development and Calibration of the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim), Version 3.02-CG. http://baydeltaoffice.water.ca.gov/modeling/hydrology/C2VSim/download/C2VSim_Model_Report_201 6-03_vR374.pdf.

CDM, 2008. Northeastern San Joaquin County Groundwater Banking Authority Integrated Conjunctive Use Project: Groundwater Model Documentation for IRWMP Simulations Technical Memorandum.

Dogrul, Emin C., Tariq N. Kadir, and Charles F. Brush, 2017a. Integrated Water Flow Model Theoretical Documentation (IWFM-2015), Revision 630. http://baydeltaoffice.water.ca.gov/modeling/ hydrology/IWFM/IWFM-2015/v2015_0_630/downloadables/IWFM-2015.0.630_Theoretical Documentation.pdf.

Dogrul, Emin C., Tariq N. Kadir, and Charles F. Brush, 2017b. DWR Technical Memorandum: Theoretical Documentation and User’s Manual for IWFM Demand Calculator (IDC-2015), Revision 63. Bay-Delta Office, California Department of Water Resources. http://baydeltaoffice. water.ca.gov/modeling/hydrology/IDC/IDC-2015/v2015_0_63/index_ IDCv2015_0_63.cfm.

Department of Water Resources (DWR). Land Use Surveys. Downloaded various counties and years from 1993-2000. http://www.water.ca.gov/landwateruse/lusrvymain.cfm Department of Water Resources (DWR). Statewide Crop Mapping 2014. Downloaded for three groundwater subbasins in model area. https://gis.water.ca.gov/app/CADWRLandUseViewer/.

Department of Water Resources (DWR), 2017. IWFM Soil Data Builder with GIS User’s Manual. Version

1.0.41. http://baydeltaoffice.water.ca.gov/modeling/hydrology/IWFM/SupportTools/index_ Support Tools .cfm.

Irrigation Training and Research Center (ITRC), California Polytechnic State University San Luis Obispo.

California Evapotranspiration Data. CIMIS Zone 12, Water Balance Data, Sprinkler Irrigation, Typical Year. http://www.itrc.org/etdata/index.html.

Oakdale Irrigation District (OID), March 2016. 2015 Agricultural Water Management Plan. Prepared by Davids Engineering. http://www.water.ca.gov/wateruseefficiency/sb7/docs/2016/Oakdale% 20ID%20201 5%20AWMP.pdf.

Page, R.W., 1974. Base and thickness of the Post-Eocene continental deposits in the Sacramento Valley, California. USGS Water-Resources Investigations Report 73-45.

Prichard, Terry L. Winegrape Irrigation Scheduling Using Deficit Irrigation Techniques. University of California, Davis. http://ucanr.edu/sites/ce_san_joaquin/files/ 35706.pdf.

ATTACHMENT 2
San Joaquin County 6-2 Woodard & Curran
ESJWRM Report August 2018
South San Joaquin Irrigation District (SSJID), December 2015. 2015 Agricultural Water Management Plan.

Prepared by Davids Engineering. http://www.water.ca.gov/wateruseefficiency/sb7/docs/2015/ plans/SSJID%20AWMP%202015%20FINAL.pdf.

United States Department of Agriculture (USDA), 2017a. Natural Resources Conservation Service (NRCS) Web Soil Survey SSURGO Database. https://websoilsurvey.nrcs.usda.gov/.

United States Department of Agriculture (USDA), 2017b. Natural Resources Conservation Service (NRCS) Web Soil Survey United States General Soil Map. https://websoilsurvey.nrcs.usda.gov/.

United States Department of Agriculture (USDA) National Agricultural Statistics Service (NASS). Cropland Data Layers. Downloaded 2007-2015. USDA-NASS, Washington, DC. https://nassgeodata.gmu.edu/CropScape/.

United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), 2009.

National Engineering Handbook Part 630. Chapter 7: Hydrologic Soil Groups.

Williamson, A.K., D.E. Prudic, and L.A. Swain, 1989. Ground-water flow in the Central Valley, California.

USGS Professional Paper 1401-D.

ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018

FIGURES
Figure 1: ESJ Subbasin with County Lines
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 2: Groundwater Subbasins
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 3a: ESJ Subbasin Major Water Purveyors
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 3b: ESJ Subbasin Groundwater Sustainability Agencies ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 4: ESJWRM Boundaries
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 5: ESJWRM Grid Development Features
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 6: ESJWRM Elements
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 7: ESJWRM Subregions
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 8: ESJWRM Subareas
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 9: ESJWRM Streams and Stream Inflow Locations
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 10: ESJWRM Average Annual Precipitation
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 11: ESJWRM Annual Rainfall
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 12: ESJWRM Hydrologic Soil Group
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 13: ESJWRM General Land Use in 1995 DWR Land Use Survey ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 14: ESJWRM General Land Use in 2015 CropScape
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 15: ESJWRM ESJ Subbasin Annual General Land Use
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 16: ESJWRM Cropping Pattern in 1995 DWR Land Use Survey ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 17: ESJWRM Cropping Pattern in 2014 Land IQ
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 18: ESJWRM Cropping Pattern in 2015 CropScape
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 19a: ESJWRM Annual Cropping Pattern – Eastern San Joaquin Subbasin Figure 19b: ESJWRM Annual Cropping Pattern – Subarea 1 (North Delta Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 19c: ESJWRM Annual Cropping Pattern – Subarea 2 (North Subarea) Figure 19d: ESJWRM Annual Cropping Pattern – Subarea 3 (Calaveras Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 19e: ESJWRM Annual Cropping Pattern – Subarea 4 (Central Subarea) Figure 19f: ESJWRM Annual Cropping Pattern – Subarea 5 (South Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 19g: ESJWRM Annual Cropping Pattern – Subarea 6 (Stanislaus Subarea) Figure 20: ESJWRM Annual Evapotranspiration
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 21: ESJWRM Surface Water Drainage Watersheds
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 22: ESJWRM Ground Surface Elevation
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 23: ESJWRM Layer 1 Thickness
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 24: ESJWRM Corcoran Clay Depth to Top
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 25: ESJWRM Corcoran Clay Thickness
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 26: ESJWRM Layer 2 Thickness
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 27: ESJWRM Layer 3 Thickness
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 28: ESJWRM Layer 4 Thickness
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 29a: ESJWRM Cross Section A - A’
Figure 29b: ESJWRM Cross Section B - B’
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 29c: ESJWRM Cross Section C - C’
Figure 29d: ESJWRM Cross Section D - D’
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 29e: ESJWRM Cross Section E - E’
Figure 29f: ESJWRM Cross Section F - F’
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 30: ESJWRM Small Watersheds
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 31: ESJWRM Initial GW Levels (Fall 1994)
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 32: ESJWRM Annual Population by Urban Center
Figure 33: ESJWRM Annual Per Capita Water Use by Urban Center ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 34: ESJWRM Surface Water Diversion Locations
Diversion
#26
Diversion #27
Diversion
#11
Diversion
#10
Diversion
#12
Diversion
#32
Diversion
#30
Diversions
#5 and 28
Diversions
#1, 2, 3,
and 4
Diversions
#6, 8, 9,
and 29
Diversion
#7
Diversion
#31 Diversions
#24 and 25
Diversions
#13, 14,
15, 16, 17,
18, 19, 20,
21, 22, 23,
and 33
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 35: ESJWRM Groundwater Production Wells
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 36: ESJWRM Riparian Surface Water Diversion Areas ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 37: ESJWRM Field Capacity
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 38: ESJWRM Wilting Point
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 39: ESJWRM Total Porosity
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 40: ESJWRM Saturated Hydraulic Conductivity
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 41: ESJWRM Pore Size Distribution Index
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 42a: ESJWRM Agricultural Water Demand – Eastern San Joaquin Subbasin Figure 42b: ESJWRM Unit Agricultural Water Use and ETAW – Eastern San Joaquin Subbasin ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 42c: ESJWRM Agricultural Water Demand – Subarea 1 (North Delta Subarea) Figure 42d: ESJWRM Unit Agricultural Water Use and ETAW – Subarea 1 (North Delta Subarea)
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 42e: ESJWRM Agricultural Water Demand – Subarea 2 (North Subarea) Figure 42f: ESJWRM Unit Agricultural Water Use and ETAW – Subarea 2 (North Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 42g: ESJWRM Agricultural Water Demand – Subarea 3 (Calaveras Subarea) Figure 42h: ESJWRM Unit Agricultural Water Use and ETAW – Subarea 3 (Calaveras Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 42i: ESJWRM Agricultural Water Demand – Subarea 4 (Central Subarea) Figure 42j: ESJWRM Unit Agricultural Water Use and ETAW – Subarea 4 (Central Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 42k: ESJWRM Agricultural Water Demand – Subarea 5 (South Subarea) Figure 42l: ESJWRM Unit Agricultural Water Use and ETAW – Subarea 5 (South Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 42m: ESJWRM Agricultural Water Demand – Subarea 6 (Stanislaus Subarea) Figure 42n: ESJWRM Unit Agricultural Water Use and ETAW – Subarea 6 (Stanislaus Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 43a: ESJWRM Urban Water Demand – Eastern San Joaquin Subbasin Figure 43b: ESJWRM Urban Water Demand – Subarea 1 (North Delta Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 43c: ESJWRM Urban Water Demand – Subarea 2 (North Subarea) Figure 43d: ESJWRM Urban Water Demand – Subarea 3 (Calaveras Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 43e: ESJWRM Urban Water Demand – Subarea 4 (Central Subarea) Figure 43f: ESJWRM Urban Water Demand – Subarea 5 (South Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 43g: ESJWRM Urban Water Demand – Subarea 6 (Stanislaus Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 44: ESJWRM Stream Calibration Gauges
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 45: ESJWRM Stream Bed Hydraulic Conductivity
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 46a: ESJWRM Stream Calibration Gauges Streamflow – Dry Creek near Galt Figure 46b: ESJWRM Stream Calibration Gauges Exceedance – Dry Creek near Galt ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 46c: ESJWRM Stream Calibration Gauges Streamflow – Mokelumne River at Woodbridge
Figure 46d: ESJWRM Stream Calibration Gauges Exceedance – Mokelumne River at Woodbridge
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 46e: ESJWRM Stream Calibration Gauges Streamflow – Mormon Slough at Bellota Figure 46f: ESJWRM Stream Calibration Gauges Exceedance – Mormon Slough at Bellota ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 46g: ESJWRM Stream Calibration Gauges Streamflow – Stanislaus River below Orange Blossom Bridge
Figure 46h: ESJWRM Stream Calibration Gauges Exceedance – Stanislaus River below Orange Blossom Bridge
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 46i: ESJWRM Stream Calibration Gauges Streamflow – San Joaquin River below Garwood Bridge at Stockton
Figure 46j: ESJWRM Stream Calibration Gauges Exceedance – San Joaquin River below Garwood Bridge at Stockton
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 47a: ESJWRM Agricultural Land and Water Use Budget – Eastern San Joaquin Subbasin Figure 47b: ESJWRM Agricultural Land and Water Use Budget – Subarea 1 (North Delta Subarea)
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 47c: ESJWRM Agricultural Land and Water Use Budget – Subarea 2 (North Subarea) Figure 47d: ESJWRM Agricultural Land and Water Use Budget – Subarea 3 (Calaveras Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 47e: ESJWRM Agricultural Land and Water Use Budget – Subarea 4 (Central Subarea) Figure 47f: ESJWRM Agricultural Land and Water Use Budget – Subarea 5 (South Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 47g: ESJWRM Agricultural Land and Water Use Budget – Subarea 6 (Stanislaus Subarea)
Figure 48a: ESJWRM Urban Land and Water Use Budget – Eastern San Joaquin Subbasin ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 48b: ESJWRM Urban Land and Water Use Budget – Subarea 1 (North Delta Subarea) Figure 48c: ESJWRM Urban Land and Water Use Budget – Subarea 2 (North Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 48d: ESJWRM Urban Land and Water Use Budget – Subarea 3 (Calaveras Subarea) Figure 48e: ESJWRM Urban Land and Water Use Budget – Subarea 4 (Central Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 48f: ESJWRM Urban Land and Water Use Budget – Subarea 5 (South Subarea) Figure 48g: ESJWRM Urban Land and Water Use Budget – Subarea 6 (Stanislaus Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 49a: ESJWRM Groundwater Budget – Eastern San Joaquin Subbasin Figure 49b: ESJWRM Groundwater Budget – Subarea 1 (North Delta Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 49c: ESJWRM Groundwater Budget – Subarea 2 (North Subarea) Figure 49d: ESJWRM Groundwater Budget – Subarea 3 (Calaveras Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 49e: ESJWRM Groundwater Budget – Subarea 4 (Central Subarea) Figure 49f: ESJWRM Groundwater Budget – Subarea 5 (South Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 49g: ESJWRM Groundwater Budget – Subarea 6 (Stanislaus Subarea) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 50: ESJWRM Groundwater Level Calibration Wells
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 51a: ESJWRM Groundwater Level Contours (Fall 2015) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 51b: ESJWRM Groundwater Level Contours (Spring 2015) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 51c: ESJWRM Groundwater Level Contours (Fall 2013) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 51d: ESJWRM Groundwater Level Contours (Spring 2011) ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 52a: ESJWRM Groundwater Level Hydrograph – Hydrograph #1 Figure 52b: ESJWRM Groundwater Level Hydrograph – Hydrograph #2 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 52c: ESJWRM Groundwater Level Hydrograph – Hydrograph #3 Figure 52d: ESJWRM Groundwater Level Hydrograph – Hydrograph #4 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 52e: ESJWRM Groundwater Level Hydrograph – Hydrograph #5 Figure 52f: ESJWRM Groundwater Level Hydrograph – Hydrograph #6 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 52g: ESJWRM Groundwater Level Hydrograph – Hydrograph #7 Figure 52h: ESJWRM Groundwater Level Hydrograph – Hydrograph #8 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 52i: ESJWRM Groundwater Level Hydrograph – Hydrograph #9 Figure 52j: ESJWRM Groundwater Level Hydrograph – Hydrograph #10 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 52k: ESJWRM Groundwater Level Hydrograph – Hydrograph #11 Figure 52l: ESJWRM Groundwater Level Hydrograph – Hydrograph #12 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 52m: ESJWRM Groundwater Level Hydrograph – Hydrograph #13 Figure 52n: ESJWRM Groundwater Level Hydrograph – Hydrograph #14 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 52o: ESJWRM Groundwater Level Hydrograph – Hydrograph #15 Figure 52p: ESJWRM Groundwater Level Hydrograph – Hydrograph #16 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 52q: ESJWRM Groundwater Level Hydrograph – Hydrograph #17 Figure 52r: ESJWRM Groundwater Level Hydrograph – Hydrograph #18 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 53: ESJWRM ESJ Subbasin Groundwater Level Histogram Figure 54: ESJWRM ESJ Subbasin Groundwater Level Scatter Plot ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 55: ESJWRM Parametric Grid
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 56: ESJWRM Layer 1 Horizontal Hydraulic Conductivity ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 57: ESJWRM Layer 2 Horizontal Hydraulic Conductivity ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 58: ESJWRM Layer 3 Horizontal Hydraulic Conductivity ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 59: ESJWRM Layer 1 Specific Storage
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 60: ESJWRM Layer 2 Specific Storage
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 61: ESJWRM Layer 3 Specific Storage
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 62: ESJWRM Layer 1 Specific Yield
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 63: ESJWRM Layer 2 Specific Yield
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 64: ESJWRM Layer 3 Specific Yield
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 65: ESJWRM Sensitivity Analysis of Horizontal Hydraulic Conductivity – Difference in Average Groundwater Elevation (feet)
Figure 66: ESJWRM Sensitivity Analysis of Horizontal Hydraulic Conductivity – Relative Root Mean Square Error
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 67: ESJWRM Sensitivity Analysis of Vertical Hydraulic Conductivity – Difference in Average Groundwater Elevation (feet)
Figure 68: ESJWRM Sensitivity Analysis of Vertical Hydraulic Conductivity – Relative Root Mean Square Error
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 69: ESJWRM Sensitivity Analysis of Specific Storage – Difference in Average Groundwater Elevation (feet)
Figure 70: ESJWRM Sensitivity Analysis of Specific Storage – Relative Root Mean Square Error ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 71: ESJWRM Sensitivity Analysis of Specific Yield – Difference in Average Groundwater Elevation (feet)
Figure 72: ESJWRM Sensitivity Analysis of Specific Yield – Relative Root Mean Square Error ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure 73: ESJWRM Sensitivity Analysis of Streambed Conductance – Difference in Average Groundwater Elevation (feet)
Figure 74: ESJWRM Sensitivity Analysis of Streambed Conductance – Relative Root Mean Square Error
ATTACHMENT 2

woodardcurran.com

COMMITMENT & INTEGRITY DRIVE RESULTS
ATTACHMENT 2

EASTERN SAN JOAQUIN WATER RESOURCES MODEL
(ESJWRM)
Final Report
August 2018
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
APPENDIX A: PRESENTATIONS TO TECHNICAL REVIEW COMMITTEE ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
APPENDIX B: ESJWRM IDC TECHNICAL MEMORANDUM
ATTACHMENT 2
February 2018 1
Technical Memorandum
SGMA Readiness Project
Subject: Eastern San Joaquin Water Resources Model
Agricultural and Urban Demand Estimates (Task 2 Deliverable) Prepared For: San Joaquin County
Prepared by: Sara Miller
Reviewed by: Ali Taghavi
Date: 2/1/2018
Reference: 0541002 Task 2
1 Introduction
The purpose of this Technical Memorandum is to document the data and information used in analyzing land surface processes, to briefly discuss the analytical tools used, and to present estimates of the agricultural and urban water use in the Eastern San Joaquin Groundwater Subbasin (ESJ Subbasin) as part of the development of the Eastern San Joaquin Water Resources Model (ESJWRM).

The IWFM Demand Calculator (IDC) (Dogrul et al., 2017) is used to estimate the agricultural and urban water use in the ESJ Subbasin portion of ESJWRM. IDC, the stand-alone version of the Integrated Water Flow Model’s (IWFM) root zone component, calculates agricultural and urban water demands with major inputs including climate conditions, soil parameters, and land use types and distribution. The hydrologic period of the ESJWRM spans from October 1994 though September 2015 and covers water years 1995 through 2015.

The ESJWRM boundaries include the ESJ Subbasin (primary model area), as well as the Cosumnes Subbasin to the north and the Modesto Subbasin to the south. The model network is a Finite Element based grid that contains 16,054 elements and 15,302 nodes. The model elements are grouped into 20 model subregions that are used to organize input data for the model and to report standard model output water budgets (Figure 1). These subregions are aggregated into 8 larger units (model subareas) used to output model results for basin-scale planning (Figure 2). ESJ Subbasin, the primary model area, is made up of 18 subregions and is the focus of this Technical Memorandum. 2 Technical Review and Oversight
The development of the ESJWRM, including the development and calibration of IDC, is taking place in an open and transparent process. The Eastern San Joaquin County Groundwater Basin Authority (GBA) was the organizational structure for model development coordination before the creation of the Eastern San Joaquin Groundwater Authority (GWA). The GBA’s Ad Hoc Technical Review Committee was the forum to review model input data and assumptions, as well as calibration results. The monthly committee meetings were open to all interested parties and generally consisted of technical representatives from local agencies, consultants with knowledge of the area, representatives for neighboring groundwater subbasins, DWR staff, and San Joaquin County personnel.

Local agencies with consistent representation included San Joaquin County, Woodbridge Irrigation District, City of Lodi, North San Joaquin Water Conservation District, Lockeford Community Services District, Calaveras County Water District, City of Stockton, Cal Water, Stockton East Water District, City of ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 2
Lathrop, City of Manteca, South San Joaquin Irrigation District, City of Escalon, Oakdale Irrigation District, and Stanislaus County.
3 Land Use
Spatial land use data was used to develop land use and crop acreages for each model element. Model element acreages were then aggregated by subregion for reporting and verification purposes.

The Department of Water Resources (DWR) conducts periodic land use surveys for each county that include over 70 different crop categories, as well as urban and native vegetation (DWR, 1993-2000). DWR land use surveys by county were merged and assumed to represent water year 1995 in the model. The surveys used include:

1. San Joaquin County (1996)

2. Sacramento County (1993)

3. Amador County (1997)

4. Calaveras County (2000)

5. Stanislaus County (1996)
Data for water years 2007 through 2015 are from the United States Department of Agriculture’s remote sensing CropScape data (USDA NASS, 2007-2015). CropScape includes 256 land use categories that come from annual satellite imagery collected during the growing season on 30 meter by 30 meter pixels. Based on reports on the CropScape website, the level of accuracy for this data is about 85-97% for crop-specific land cover categories. Although this level of accuracy is high, the accuracy varies depending on many factors, including the time of the satellite image, growing season timing, cloud cover, type of crop, and maturity state of the crop.

DWR retained LandIQ, LLC to develop a statewide assessment of agricultural land use in summer 2014.

LandIQ used remote sensing methods to collect and process the data, which was then ground truthed for a reported overall accuracy of 96.6% (DWR, 2014). In ESJWRM, this data was broadly used as verification of CropScape 2014 data and, in a few specific cases, as replacement or enhancement of the CropScape data.

Local data and knowledge was also utilized to refine and correct, as needed, the cropping acreages developed based on the DWR land use surveys and CropScape years. ESJWRM includes 23 irrigated crop categories and 4 general land use categories. The irrigated crop categories were combined into 6 high-level groupings of crops with similar water use or irrigation practices. Table 1 lists the land use categories.

To fill the gap between 1995 and 2007, all land use and crop categories were interpolated at the spatial resolution level of the model element. Thus, the geographic distribution of interpolated land use and cropping patterns are honored. Adjustments were made, as needed, at the element level to ensure that the land use and cropping pattern trends over time are reflective of local data. These adjustments were mostly based on local knowledge and information received from various entities, including irrigation districts, water districts, and municipalities.

Figure 3 and Figure 4 show the spatial distribution of the major land use categories in the ESJ Subbasin.

Figure 5 shows the annual trends of land use categories in the ESJ Subbasin.

Figure 6, Figure 7, and Figure 8 show the spatial distribution of the irrigated crops for 1995, 2014, and 2015. Figure 9a-9m show the annual cropping patterns, by high level categories, for the ESJ Subbasin and those major model input subregions that are not predominantly urban centers (i.e., all subregions in the primary model area except subregions 3, 6, 9, 10, 12, and 16).

ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 3
Table 1: Land Use Categories
Land Use Type Model Category Grouped Categories
Irrigated Crops
Almonds
Fruit and Nut Trees
Cherries
Citrus & Subtropical
Other Orchard
Pistachios
Walnuts
Vineyards Vineyards
Alfalfa Alfalfa and Irrigated
Pasture Pasture
Grain Grain
Corn
Field Crops
Cotton
Dry Beans
Field Crops
Safflower
Sugar Beets
Cucurbits
Truck Crops
Onion & Garlic
Potatoes
Tomato Fresh
Tomato Processing
Truck Crops
Rice Rice
Other Land Use
Urban Landscape
Water Surface
Riparian Vegetation
Native Vegetation
4 Urban Demand
IDC calculates urban demand based on per capita water use, population, and the breakdown of indoor versus outdoor water use by month. Figure 10 shows the annual population trends for each urban center. Figure 11 shows the annual per capita water use values of these urban centers used in the calculation of urban water demand. Figure 12a-12g show the model estimated annual urban demand for predominantly urban subregions and the total ESJ Subbasin area.

Population and per capita water use for the major urban areas were largely provided directly by the urban areas or were contained in Urban Water Management Plans (UWMPs). Additional annual population, including an estimate for rural urban areas, came from the United States Census Bureau and the California Department of Finance. Monthly per capita water use, commonly reported in gallons per capita per day (GPCD), was generally estimated for each urban entity using the annual population and monthly urban water use (provided by cities based on water delivery records). To estimate the urban water demand of rural domestic water areas, the average major urban area GPCD was combined with the estimated rural population.

It was assumed that an annual average of 60% of urban water was used indoors and 40% was used outdoors.

The monthly fractions entered into the model had the majority of urban water demand due to indoor activities from November through March and up to a maximum of 60% of urban water used outdoors for the remainder of the year.

ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 4
The indoor/outdoor breakdown received concurrence from the urban water providers who attended the Ad Hoc Technical Review Committee meetings. Population and per capita water use data were reviewed by the major urban areas and confirmed at the meetings (pers. comm. Kathryn Garcia, Andrew Richle, Michael Bolzowski, Greg Gibson, and Elba Mijango).
5 Agricultural Demand
IDC estimates agricultural water demand based on model input data for evapotranspiration (ET), monthly precipitation, return and reuse fractions, irrigation period, land use and cropping acreages, and soil properties (e.g., hydraulic conductivity, pore size distribution index, etc.). This data was compiled, analyzed, synthesized, and processed for input in ESJWRM.

The ET requirement is based on a variety of sources, including locally-developed data for the South San Joaquin Irrigation District and the Oakdale Irrigation District Agricultural Water Management Plans (AWMPs) (SJJID, 2015; OID, 2016) and averages for DWR’s CIMIS (California Irrigation Management Information System) Zone 12 developed using the METRIC methodology, which is a remote-sensing based technology to estimate crop actual ET. Based on discussions with locals (pers. comm. Jennifer Spaletta and Bryan Thoreson), deficit irrigation of vineyards was simulated in ESJWRM with reference to the growing season ET values in the Lodi area (Prichard). Figure 13 shows the range in annual evapotranspiration rates from the various sources for the 27 model land use categories.

Monthly rainfall data was derived from the PRISM (OSU, 1970-2015) database and mapped to the model element in order to preserve the spatial distribution of the monthly rainfall over the model hydrologic period of 1995 through 2015. Figure 14 shows the annual rainfall in the model area and the cumulative departure from mean, which is an indication of long-term rainfall trends in the area.

The soil properties included in the model for each element are field capacity, wilting point, total porosity, hydraulic conductivity, and pore size distribution index. The soil survey geographic (SSURGO) database was downloaded first from the Web Soil Survey and any gaps in data were filled in using the General Soil Map of the United States (STATSGO2). These spatial datasets were averaged over each model element using IWFM’s Soil Data Builder with GIS tool available at http://baydeltaoffice.water.ca.gov/modeling/ hydrology/IWFM/SupportTools/index_SupportTools.cfm.

IDC was used to simulate the monthly agricultural demand estimates for each model element. The IDC model was calibrated to agricultural water use values reported by irrigation districts in their AWMPs and then checked against local data with input from irrigation district representatives and consultants (pers. comm. Doug Heberle, Jennifer Spaletta, Tom Flinn, Peter Martin, Cathy Lee, Manuel Verduzco, Sam Bologna, Bryan Thoreson, Emily Sheldon, Eric Thorburn, and Byron Clark). ESJWRM as a whole will undergo a more rigorous calibration process comparing model streamflow and groundwater levels to actual observed data.

The calibrated IDC was used to estimate monthly agricultural water demand at each model element during the model hydrologic period. The element-level estimates were then aggregated to report the information for each model subregion. Figure 15a-15n show the agricultural water demand, unit agricultural water use, and unit evapotranspiration of applied water (ETAW) estimates by the total ESJ Subbasin area and the subregions with irrigation districts who participated in the IDC development and calibration process.

The IDC model will be integrated with the comprehensive IWFM model, ESJWRM, to simulate the surface water and groundwater conditions in the ESJ Subbasin.

ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 5
6 References
Department of Water Resources (DWR). Statewide Crop Mapping 2014. Downloaded for three groundwater subbasins in model area. https://gis.water.ca.gov/app/CADWRLandUseViewer/.

Department of Water Resources (DWR). Land Use Surveys. Downloaded various counties and years from 1993-2000. http://www.water.ca.gov/landwateruse/lusrvymain.cfm Dogrul, Emin C., Tariq N. Kadir, and Charles F. Brush, August 2017. DWR Technical Memorandum:

Theoretical Documentation and User’s Manual for IWFM Demand Calculator (IDC-2015), Revision 63. Bay-Delta Office, California Department of Water Resources. http://baydeltaoffice. water.ca.gov/modeling/hydrology/IDC/IDC-2015/v2015_0_63/index_ IDCv2015_0_63.cfm.

Irrigation Training and Research Center (ITRC), California Polytechnic State University San Luis Obispo.

California Evapotranspiration Data. CIMIS Zone 12, Water Balance Data, Sprinkler Irrigation, Typical Year. http://www.itrc.org/etdata/index.html.

Oakdale Irrigation District (OID), March 2016. 2015 Agricultural Water Management Plan. Prepared by Davids Engineering.
http://www.water.ca.gov/wateruseefficiency/sb7/docs/2016/Oakdale%20ID%20201 5%20AWMP.pdf.

Oregon State University (OSU). PRISM Climate Group. Downloaded 1970-2015. http://prism.oregonstate.edu.

Prichard, Terry L. Winegrape Irrigation Scheduling Using Deficit Irrigation Techniques. University of California, Davis. http://ucanr.edu/sites/ce_san_joaquin/files/ 35706.pdf.

South San Joaquin Irrigation District (SSJID), December 2015. 2015 Agricultural Water Management Plan.

Prepared by Davids Engineering. http://www.water.ca.gov/wateruseefficiency/sb7/docs/2015/ plans/SSJID%20AWMP%202015%20FINAL.pdf.

Web Soil Survey. Natural Resources Conservation Service, United States Department of Agriculture. https://websoilsurvey.nrcs.usda.gov/.

United States Department of Agriculture (USDA) National Agricultural Statistics Service (NASS).

Cropland Data Layers. Downloaded 2007-2015. USDA-NASS, Washington, DC. https://nassgeodata.gmu.edu/CropScape/.

ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 6
Figure 1: Model Subregions
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 7
Figure 2: Model Subareas with Eastern San Joaquin Subbasin ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 8
Figure 3: General Land Use in 1995 DWR Land Use Survey
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 9
Figure 4: General Land Use in 2015 CropScape
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 10
Figure 5: Eastern San Joaquin Subbasin General Land Use Acreages 0 100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Land Use Acreage
Water Year
Urban
Landscape
Water Surface
Riparian
Vegetation
Native
Vegetation
Irrigated Crops
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 11
Figure 6: Cropping Pattern in 1995 DWR Land Use Survey
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 12
Figure 7: Cropping Pattern in 2014 LandIQ
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 13
Figure 8: Cropping Pattern in 2015 CropScape
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 14
Figure 9a: Irrigated Crop Acreages- Eastern San Joaquin Subbasin Figure 9b: Irrigated Crop Acreages- Subregion 1 (North Delta Subregion) 0 50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
0 10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 15
Figure 9c: Irrigated Crop Acreages- Subregion 2 (Woodbridge Subregion) Figure 9d: Irrigated Crop Acreages- Subregion 4 (North San Joaquin Subregion) 0 5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
0 10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 16
Figure 9e: Irrigated Crop Acreages- Subregion 5 (Calaveras Subregion) Figure 9f: Irrigated Crop Acreages- Subregion 7 (Stockton East Subregion) 0 500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
0 10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 17
Figure 9g: Irrigated Crop Acreages- Subregion 8 (Central San Joaquin Subregion) Figure 9h: Irrigated Crop Acreages- Subregion 11 (South San Joaquin East Subregion) 0 10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
0 10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 18
Figure 9i: Irrigated Crop Acreages- Subregion 13 (Oakdale West Subregion) Figure 9j: Irrigated Crop Acreages- Subregion 14 (South Delta Subregion) 0 2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
0 2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 19
Figure 9k: Irrigated Crop Acreages- Subregion 15 (South San Joaquin West Subregion) Figure 9l: Irrigated Crop Acreages- Subregion 17 (Stanislaus Subregion) 0 2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
0 2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 20
Figure 9m: Irrigated Crop Acreages- Subregion 18 (Oakdale East Subregion) Figure 10: Urban Population Centers in Eastern San Joaquin Subbasin 0 2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Irrigated Crop Acreage
Water Year
Truck Crops
Rice
Field Crops
Grain
Alfalfa and
Irrigated
Pasture
Vineyards
Fruit and Nut
Trees
0 20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Urban Population
Water Year
Cal Water
Escalon
Lathrop
Linden County
Lockeford
Lodi
Manteca
Ripon
Stockton
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 21
Figure 11: Urban Per Capita Water Use in Eastern San Joaquin Subbasin Figure 12a: Urban Demand- Eastern San Joaquin Subbasin
0 50
100
150
200
250
300
350
400
450
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Urban Per Capita Water Use (GPCD)
Water Year
Cal Water
Escalon
Lathrop
Linden County
Lockeford
Lodi
Manteca
Ripon
Stockton
0 20,000
40,000
60,000
80,000
100,000
120,000
140,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Urban Demand (Acre-Feet)
Water Year
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 22
Figure 12b: Urban Demand- Subregion 3 (Lodi Subregion)
Figure 12c: Urban Demand- Subregion 6 (Stockton Subregion) 0 2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Urban Demand (Acre-Feet)
Water Year
0 10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Urban Demand (Acre-Feet)
Water Year
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 23
Figure 12d: Urban Demand- Subregion 9 (Lathrop Subregion) Figure 12e: Urban Demand- Subregion 10 (Manteca Subregion) 0 500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Urban Demand (Acre-Feet)
Water Year
0 2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Urban Demand (Acre-Feet)
Water Year
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 24
Figure 12f: Urban Demand- Subregion 12 (Escalon Subregion) Figure 12g: Urban Demand- Subregion 16 (Ripon Subregion) 0 500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Urban Demand (Acre-Feet)
Water Year
0 1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Urban Demand (Acre-Feet)
Water Year
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 25
Figure 13: Annual Crop Evapotranspiration
Figure 14: Annual Precipitation
0 5
10 15
20 25
30 0
5 10
15 20
25 30
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Cumulative Departure from Mean
Precipitation (inches)
Annual Precipitation (inches)
Water Year
Annual Precipitation
Cumulative Departure from Mean
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 26
Figure 15a: Agricultural Demand- Eastern San Joaquin Subbasin Figure 15b: Unit Agricultural Water Use and ETAW- Eastern San Joaquin Subbasin 0 200,000
400,000
600,000
800,000
1,000,000
1,200,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Agricultural Demand (Acre-Feet)
Water Year

0.00 0.50

1.00 1.50

2.00 2.50

3.00 3.50

4.00 199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Feet
Water Year
Unit Ag Water Use Unit ETAW
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 27
Figure 15c: Agricultural Demand- Subregion 2 (Woodbridge Subregion) Figure 15d: Unit Agricultural Water Use and ETAW- Subregion 2 (Woodbridge Subregion) 0 10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Agricultural Demand (Acre-Feet)
Water Year

0.00 0.50

1.00 1.50

2.00 2.50

3.00 3.50

4.00 199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Feet
Water Year
Unit Ag Water Use Unit ETAW
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 28
Figure 15e: Agricultural Demand- Subregion 4 (North San Joaquin Subregion) Figure 15f: Unit Agricultural Water Use and ETAW- Subregion 4 (North San Joaquin Subregion) 0 20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
200,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Agricultural Demand (Acre-Feet)
Water Year

0.00 0.50

1.00 1.50

2.00 2.50

3.00 3.50

4.00 199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Feet
Water Year
Unit Ag Water Use Unit ETAW
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 29
Figure 15g: Agricultural Demand- Subregion 7 (Stockton East Subregion) Figure 15h: Unit Agricultural Water Use and ETAW- Subregion 7 (Stockton East Subregion) 0 20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
200,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Agricultural Demand (Acre-Feet)
Water Year

0.00 0.50

1.00 1.50

2.00 2.50

3.00 3.50

4.00 199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Feet
Water Year
Unit Ag Water Use Unit ETAW
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 30
Figure 15i: Agricultural Demand- Subregion 11 (South San Joaquin East Subregion) Figure 15j: Unit Agricultural Water Use and ETAW- Subregion 11 (South San Joaquin East Subregion) 0 20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
200,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Agricultural Demand (Acre-Feet)
Water Year

0.00 0.50

1.00 1.50

2.00 2.50

3.00 3.50

4.00 199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Feet
Water Year
Unit Ag Water Use Unit ETAW
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 31
Figure 15k: Agricultural Demand- Subregion 13 (Oakdale West Subregion) Figure 15l: Unit Agricultural Water Use and ETAW- Subregion 13 (Oakdale West Subregion) 0 5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
50,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Agricultural Demand (Acre-Feet)
Water Year

0.00 0.50

1.00 1.50

2.00 2.50

3.00 3.50

4.00 199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Feet
Water Year
Unit Ag Water Use Unit ETAW
ATTACHMENT 2
SGMA Readiness Project
IDC Development and Surface Water Budget
February 2018 32
Figure 15m: Agricultural Demand- Subregion 18 (Oakdale East Subregion) Figure 15n: Unit Agricultural Water Use and ETAW- Subregion 18 (Oakdale East Subregion) 0 10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Agricultural Demand (Acre-Feet)
Water Year

0.00 0.50

1.00 1.50

2.00 2.50

3.00 3.50

4.00 199519961997199819992000200120022003200420052006200720082009201020112012201320142015 Feet
Water Year
Unit Ag Water Use Unit ETAW
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
APPENDIX C: ESJWRM CALIBRATION WELLS
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-1: ESJWRM Groundwater Level Calibration Wells
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Table C-1: ESJWRM Groundwater Level Calibration Wells
Hydrograph
ID
ID by
Model
Subregion
Well Name Well Source Agency* Well Type Depth Screening Intervals
1 101 05N05E32M001 Voluntary SJCFCWCD Stockwatering 145 Unknown 2 102 04N05E10K001 CASGEM SJCFCWCD Residential 115 90/115 3 103 04N04E24F001M Voluntary DWR Observation 20 Unknown 4 201 04N05E13H001 CASGEM SJCFCWCD Irrigation 190 50/190 5 202 04N06E29N002 Voluntary SJCFCWCD Irrigation 475 204/475 6 203 04N06E34J002 Voluntary SJCFCWCD Irrigation 466 94/167, 172/466
7 204 03N05E13L001 Voluntary SJCFCWCD Irrigation 65 Unknown 8 205 03N06E17A004 Voluntary SJCFCWCD Unknown 128 60/128 9 301 Lodi Well 7 Local Agency City of Lodi Production 422 142/422 10 302 Lodi Well 2 Local Agency City of Lodi Production 315 109/310 11 303 Lodi G-25B Local Agency City of Lodi Observation 150 140/150 12 304 Lodi MW-19 CASGEM SJCFCWCD Observation 73 58/73
13 401 05N07E34G001M Voluntary DWR Irrigation 590 Unknown 14 402 04N06E12N002 CASGEM SJCFCWCD Irrigation 320 104/320 15 403 04N07E33H001 Voluntary SJCFCWCD Irrigation 104 Unknown 16 404 04N07E36L001 Voluntary DWR Irrigation 565 Unknown 17 405 04N08E32N001 Voluntary SJCFCWCD Irrigation Unknown Unknown 18 406 03N06E24M003M Voluntary DWR Irrigation 237 156/237 19 501 CCWD 010 CASGEM CCWD Observation 390 Unknown
20 502 CCWD 006 CASGEM CCWD Observation 230 Unknown
21 601 02N06E18K001M Voluntary DWR Unknown 650 Unknown
22 602 02N06E26H001 Voluntary SJCFCWCD Irrigation Unknown Unknown 23 603 01N06E05H001 Voluntary DWR Irrigation 315 235/277 24 604 01N06E12G001 Voluntary DWR Irrigation 230 210/230 25 605 01N07E32A001 Voluntary DWR Irrigation 232 178/232 26 606 01S06E02G002 Voluntary DWR Irrigation 135 101/135 27 701 02N08E03G002 Voluntary SJCFCWCD Residential 125 Unknown 28 702 02N08E18C001 Voluntary SJCFCWCD Irrigation 544 Unknown 29 703 02N07E29B001 CASGEM SJCFCWCD Irrigation 202 130/202 30 704 02N08E33E001 Voluntary SJCFCWCD Irrigation 168 Unknown 31 705 01N07E01M002 Voluntary SJCFCWCD Irrigation 364 104/108 32 801 01N09E06N001 Voluntary SJCFCWCD Irrigation 300 92/300 33 802 01N08E29M002 Voluntary SJCFCWCD Irrigation 460 Unknown 34 803 01N08E26A002 Voluntary SJCFCWCD Irrigation 216 176/216 35 804 01N09E22G002 Voluntary SJCFCWCD Irrigation 340 Unknown 36 805 01S08E05R001 Voluntary SJCFCWCD Unknown 125 Unknown ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Hydrograph
ID
ID by
Model
Subregion
Well Name Well Source Agency* Well Type Depth Screening Intervals
37 806 01S09E05H002 CASGEM SJCFCWCD Irrigation 256 148/256 38 901 01S06E11E001M Voluntary DWR Irrigation 185 Unknown 39 902 01S06E15F001M Voluntary DWR Residential 188 160/184 40 903 01S06E26K001M Voluntary DWR Irrigation 248 191/195 41 1001 01S07E18L001M Voluntary DWR Residential 248 144/154 42 1002 01S07E27K001 Voluntary SJCFCWCD Irrigation 300 120/300 43 1003 02S06E11J001 Voluntary DWR Irrigation 165 Unknown 44 1101 01S07E25R001M Voluntary DWR Irrigation 130 Unknown 45 1102 02S08E08A001 CASGEM SJCFCWCD Irrigation 180 50/180 46 1103 02S08E12D001 Voluntary DWR Residential 82 72/82 47 1104 01S08E25Q001 Voluntary SJCFCWCD Irrigation 450 Unknown 48 1105 01S09E33J002 Voluntary DWR Residential 95 88/95 49 1301 01S09E21J002 CASGEM SJCFCWCD Irrigation 223 195/223 50 1302 01S09E24R001 Voluntary SJCFCWCD Irrigation 264 176/264 51 1401 02S07E31N001 Voluntary SJCFCWCD Irrigation 226 130/226 52 1402 03S07E06Q001 Voluntary DWR Stockwatering 71 Unknown 53 1501 02S07E22N002 Voluntary DWR Irrigation 162 52/162 54 1502 02S07E26B001 Voluntary SJCFCWCD Irrigation 386 56/386 55 1601 02S07E12R001 Voluntary SJCFCWCD Residential 310 Unknown 56 1701 01S10E04C001 Voluntary DWR Unknown Unknown Unknown 57 1702 01S10E23H001M Voluntary DWR Irrigation 300 Unknown 58 1703 01S10E28J001 Voluntary DWR Unknown Unknown Unknown 59 1801 1S10E16Q1-18 Voluntary DWR Irrigation 299 Unknown 60 1802 01S10E26J001M CASGEM Stanislaus
County Unknown Unknown Unknown
61 1901 05N06E08R001M Voluntary DWR Irrigation Unknown Unknown 62 1902 06N07E08R001M Voluntary DWR Residential 332 Unknown 63 1903 05N07E10D001M Voluntary DWR Residential 260 180/260 64 1904 07N08E36B001M CASGEM SSCAWA Observation 15 Unknown 65 2001 03S08E23H001M CASGEM MID Irrigation 467 Unknown 66 2002 American 208 CASGEM MID Irrigation 320 Unknown
67 2003 03S10E17K001M CASGEM MID Irrigation 476 116/400 68 2004 Birnbaum OID-03 CASGEM STRGBA
GSA Irrigation 293
55/110,
147/154,
170/175,
185/200,
238/250,
265/270,
285/293
ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Hydrograph
ID
ID by
Model
Subregion
Well Name Well Source Agency* Well Type Depth Screening Intervals
69 2005 03S11E27G003M CASGEM STRGBA
GSA Irrigation 248 Unknown
70 2006 Paulsell 2 OID-12 CASGEM STRGBA
GSA Irrigation 815 132/159, 160/815
* CCWD = Calaveras County Water District
DWR = Department of Water Resources
MID = Modesto Irrigation District
SJCFCWCD = San Joaquin County Flood Control and Water Conservation District SSCAWA = Southeast Sacramento County Agricultural Water Authority STRGBA GSA = Stanislaus & Tuolumne Rivers Groundwater Basin Association GSA ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-2: ESJWRM Groundwater Level Hydrograph – Calibration Well #1 Figure C-3: ESJWRM Groundwater Level Hydrograph – Calibration Well #2 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-4: ESJWRM Groundwater Level Hydrograph – Calibration Well #3 Figure C-5: ESJWRM Groundwater Level Hydrograph – Calibration Well #4 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-6: ESJWRM Groundwater Level Hydrograph – Calibration Well #5 Figure C-7: ESJWRM Groundwater Level Hydrograph – Calibration Well #6 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-8: ESJWRM Groundwater Level Hydrograph – Calibration Well #7 Figure C-9: ESJWRM Groundwater Level Hydrograph – Calibration Well #8 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-10: ESJWRM Groundwater Level Hydrograph – Calibration Well #9 Figure C-11: ESJWRM Groundwater Level Hydrograph – Calibration Well #10 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-12: ESJWRM Groundwater Level Hydrograph – Calibration Well #11 Figure C-13: ESJWRM Groundwater Level Hydrograph – Calibration Well #12 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-14: ESJWRM Groundwater Level Hydrograph – Calibration Well #13 Figure C-15: ESJWRM Groundwater Level Hydrograph – Calibration Well #14 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-16: ESJWRM Groundwater Level Hydrograph – Calibration Well #15 Figure C-17: ESJWRM Groundwater Level Hydrograph – Calibration Well #16 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-18: ESJWRM Groundwater Level Hydrograph – Calibration Well #17 Figure C-19: ESJWRM Groundwater Level Hydrograph – Calibration Well #18 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-20: ESJWRM Groundwater Level Hydrograph – Calibration Well #19 Figure C-21: ESJWRM Groundwater Level Hydrograph – Calibration Well #20 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-22: ESJWRM Groundwater Level Hydrograph – Calibration Well #21 Figure C-23: ESJWRM Groundwater Level Hydrograph – Calibration Well #22 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-24: ESJWRM Groundwater Level Hydrograph – Calibration Well #23 Figure C-25: ESJWRM Groundwater Level Hydrograph – Calibration Well #24 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-26: ESJWRM Groundwater Level Hydrograph – Calibration Well #25 Figure C-27: ESJWRM Groundwater Level Hydrograph – Calibration Well #26 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-28: ESJWRM Groundwater Level Hydrograph – Calibration Well #27 Figure C-29: ESJWRM Groundwater Level Hydrograph – Calibration Well #28 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-30: ESJWRM Groundwater Level Hydrograph – Calibration Well #29 Figure C-31: ESJWRM Groundwater Level Hydrograph – Calibration Well #30 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-32: ESJWRM Groundwater Level Hydrograph – Calibration Well #31 Figure C-33: ESJWRM Groundwater Level Hydrograph – Calibration Well #32 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-34: ESJWRM Groundwater Level Hydrograph – Calibration Well #33 Figure C-35: ESJWRM Groundwater Level Hydrograph – Calibration Well #34 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-36: ESJWRM Groundwater Level Hydrograph – Calibration Well #35 Figure C-37: ESJWRM Groundwater Level Hydrograph – Calibration Well #36 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-38: ESJWRM Groundwater Level Hydrograph – Calibration Well #37 Figure C-39: ESJWRM Groundwater Level Hydrograph – Calibration Well #38 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-40: ESJWRM Groundwater Level Hydrograph – Calibration Well #39 Figure C-41: ESJWRM Groundwater Level Hydrograph – Calibration Well #40 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-42: ESJWRM Groundwater Level Hydrograph – Calibration Well #41 Figure C-43: ESJWRM Groundwater Level Hydrograph – Calibration Well #42 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-44: ESJWRM Groundwater Level Hydrograph – Calibration Well #43 Figure C-45: ESJWRM Groundwater Level Hydrograph – Calibration Well #44 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-46: ESJWRM Groundwater Level Hydrograph – Calibration Well #45 Figure C-47: ESJWRM Groundwater Level Hydrograph – Calibration Well #46 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-48: ESJWRM Groundwater Level Hydrograph – Calibration Well #47 Figure C-49: ESJWRM Groundwater Level Hydrograph – Calibration Well #48 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-50: ESJWRM Groundwater Level Hydrograph – Calibration Well #49 Figure C-51: ESJWRM Groundwater Level Hydrograph – Calibration Well #50 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-52: ESJWRM Groundwater Level Hydrograph – Calibration Well #51 Figure C-53: ESJWRM Groundwater Level Hydrograph – Calibration Well #52 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-54: ESJWRM Groundwater Level Hydrograph – Calibration Well #53 Figure C-55: ESJWRM Groundwater Level Hydrograph – Calibration Well #54 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-56: ESJWRM Groundwater Level Hydrograph – Calibration Well #55 Figure C-57: ESJWRM Groundwater Level Hydrograph – Calibration Well #56 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-58: ESJWRM Groundwater Level Hydrograph – Calibration Well #57 Figure C-59: ESJWRM Groundwater Level Hydrograph – Calibration Well #58 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-60: ESJWRM Groundwater Level Hydrograph – Calibration Well #59 Figure C-61: ESJWRM Groundwater Level Hydrograph – Calibration Well #60 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-62: ESJWRM Groundwater Level Hydrograph – Calibration Well #61 Figure C-63: ESJWRM Groundwater Level Hydrograph – Calibration Well #62 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-64: ESJWRM Groundwater Level Hydrograph – Calibration Well #63 Figure C-65: ESJWRM Groundwater Level Hydrograph – Calibration Well #64 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-66: ESJWRM Groundwater Level Hydrograph – Calibration Well #65 Figure C-67: ESJWRM Groundwater Level Hydrograph – Calibration Well #66 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-68: ESJWRM Groundwater Level Hydrograph – Calibration Well #67 Figure C-69: ESJWRM Groundwater Level Hydrograph – Calibration Well #68 ATTACHMENT 2
San Joaquin County Woodard & Curran
ESJWRM Report August 2018
Figure C-70: ESJWRM Groundwater Level Hydrograph – Calibration Well #69 Figure C-71: ESJWRM Groundwater Level Hydrograph – Calibration Well #70 ATTACHMENT 2
This page is intentionally left blank.

ATTACHMENT 2
2024
Groundwater Sustainability Plan Amendment
Complete Appendices November 2024
APPENDIX 2-B.

EASTERN SAN JOAQUIN WATER RESOURCES MODEL
(ESJWRM) REPORT VERSION 2.0 UPDATE (2022)
ATTACHMENT 2

Eastern San Joaquin
Water Resources Model
(ESJWRM)
Version 2.0 Update
Prepared for:

Eastern San Joaquin Groundwater Authority

UPDATED DRAFT
June 2, 2022
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority i Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Table of Contents
SECTION PAGE NO.
1 HISTORICAL CALIBRATION UPDATE ............................................................................................... 1

1.1 Model Code and Data Updates Since the Groundwater Sustainability Plan...............................1

1.1.1 IWFM Version...........................................................................................................................................3

1.1.2 Updated Data from the ESJWRM version used in the Stanislaus River Basin Plan ......3

1.1.3 Hydrologic Period...................................................................................................................................3

1.1.4 Precipitation..............................................................................................................................................3

1.1.5 Land Use and Cropping Patterns .....................................................................................................4

1.1.6 Stream Inflow ...........................................................................................................................................6

1.1.7 Boundary Conditions.............................................................................................................................7

1.1.8 Urban Demand ........................................................................................................................................7

1.1.9 Surface Water Diversions ....................................................................................................................8

1.1.10 Groundwater Pumping.......................................................................................................................19

1.1.11 Agricultural Operations......................................................................................................................19

1.2 Calibration Updates and Results.................................................................................................................20

1.2.1 Calibration Process...............................................................................................................................20

1.2.1.1 Agricultural Demand Calibration...................................................................................21

1.2.1.2 PEST-Assisted Aquifer Calibration.................................................................................21

1.2.2 Calibration Verification.......................................................................................................................21

1.2.2.1 Streamflow Calibration ......................................................................................................21

1.2.2.2 Groundwater Level Calibration.......................................................................................24

1.2.3 Sensitivity Analysis ...............................................................................................................................26

1.3 Historical Model Results.................................................................................................................................30

1.3.1 Land and Water Use Budget............................................................................................................30

1.3.2 Hydrologic Groundwater Budget...................................................................................................33 2 PROJECTED CONDITIONS BASELINE UPDATE ..............................................................................35

2.1 Assumptions Used to Develop Projected Conditions Baseline Update ......................................35

2.1.1 Hydrology................................................................................................................................................35

2.1.1.1 Precipitation and Hydrologic Water Year Types......................................................35

2.1.1.2 Evapotranspiration ..............................................................................................................38

2.1.1.3 Streamflow..............................................................................................................................38

2.1.2 Land Use and Cropping Patterns ...................................................................................................38

2.1.3 Water Supply and Demand ..............................................................................................................40

2.2 Projected Conditions Baseline Results......................................................................................................41

2.2.1 Land and Water Use Water Budget...............................................................................................41

2.2.2 Hydrologic Groundwater Budget...................................................................................................44 3 PROJECTED CONDITIONS BASELINE UPDATE WITH CLIMATE CHANGE ...................................46

3.1 Climate Change Background and Methods ...........................................................................................46

3.1.1 DWR Guidance.......................................................................................................................................46

3.1.2 Climate Change Methodology ........................................................................................................49

3.2 Projected Conditions Baseline with Climate Change Hydrology ...................................................49

3.2.1 Streamflow under Climate Change ...............................................................................................50 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority ii Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

3.2.1.1 Unimpaired Flows ................................................................................................................51

3.2.1.2 Impaired Flows......................................................................................................................54

3.2.2 Precipitation and Evapotranspiration under Climate Change ............................................60

3.2.2.1 Applying Change Factors to Precipitation .................................................................60

3.2.2.2 Applying Change Factors to Evapotranspiration.....................................................63

3.3 Projected Conditions Baseline with Climate Change Results ..........................................................66

3.3.1 Differences in Precipitation, Evapotranspiration, and Streamflow under Climate Change......................................................................................................................................................66

3.3.2 Land and Water Use Budget............................................................................................................68

3.3.3 Groundwater Budget...........................................................................................................................71 4 CONCLUSIONS AND RECOMMENDATIONS..................................................................................74 5 REFERENCES .....................................................................................................................................75 Tables
Table 1: Summary of ESJWRM Stream Inflow Data
Table 2: Summary of ESJWRM Surface Water Deliveries
Table 3: Summary of ESJWRM Well Pumping
Table 4: Eastern San Joaquin Subbasin Land and Water Use Budget Annual Averages Table 5: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget Annual Averages Table 6: Baseline Hydrologic Water Year Types
Table 7: ESJ Subbasin Land Use Acreages by Land Use Type Table 8: Eastern San Joaquin Subbasin Land and Water Use Budget Annual Average Table 9: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget Annual Average Table 10: DWR-Provided Datasets
Table 11: Eastern San Joaquin Stream Inflows
Table 12: San Joaquin Valley Water Year Type Designations Table 13: Comparable Water Years (based on Precipitation) Table 14: Eastern San Joaquin Subbasin Land and Water Use Budget Annual Average for PCBL-CC Table 15: Eastern San Joaquin Subbasin Land and Water Use Budget Annual Average Comparison Between the PCBL and the PCBL-CC
Table 16: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget Annual Average Table 17: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between the PCBL and the PCBL-CC
Figures
Figure 1: 2016 Land Use
Figure 2: 2016 Cropping Pattern for ESJ Subbasin
Figure 3: Streamflow Calibration
Figure 4: Groundwater Level Calibration
Figure 5: Calibration Statistics
Figure 6: Sensitivity of Groundwater Level Residual Statistics in Entire ESJWRM Figure 7: Sensitivity of Change in Groundwater Storage in ESJ Subbasin Figure 8: Sensitivity of Deep Percolation in ESJ Subbasin ATTACHMENT 2
Eastern San Joaquin Groundwater Authority iii Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 9: Eastern San Joaquin Subbasin Agricultural Demand Figure 10: Eastern San Joaquin Subbasin Urban Demand
Figure 11: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget Figure 12: Historical Precipitation in Eastern San Joaquin Subbasin Figure 13: 2018 Land Use with Urban Sphere of Influence Boundaries Figure 14: 2018 Cropping Pattern for ESJ Subbasin
Figure 15: Eastern San Joaquin Subbasin Projected Agricultural Demand Figure 16: Eastern San Joaquin Subbasin Projected Urban Demand Figure 17: Eastern San Joaquin Subbasin Projected Hydrologic Groundwater Budget Figure 18: Eastern San Joaquin Climate Change Analysis Process Figure 19: Dry Creek Hydrograph
Figure 20: Dry Creek Exceedance Curve
Figure 21: Mokelumne River Hydrograph
Figure 22: Mokelumne River Exceedance Curve
Figure 23: Calaveras River Hydrograph
Figure 24: Calaveras River Exceedance Curve
Figure 25: Stanislaus River Hydrograph
Figure 26: Stanislaus River Exceedance Curve
Figure 27: San Joaquin River Hydrograph
Figure 28: San Joaquin River Exceedance Curve
Figure 29: Tuolumne River Hydrograph
Figure 30: Tuolumne River Exceedance Curve
Figure 31: Cosumnes River Hydrograph
Figure 32: Cosumnes River Exceedance Curve
Figure 33: Perturbed Precipitation Under Climate Change Figure 34: Perturbed Precipitation Exceedance Curve
Figure 35: Subbasin Precipitation Difference with Climate Change Conditions Figure 36: Monthly Evapotranspiration Variability for Almonds Figure 37: Monthly Evapotranspiration Variability for Walnuts Figure 38: Monthly Evapotranspiration Variability for Cherries Figure 40: Simulated Changes in Precipitation due to Climate Change Figure 41: Simulated Changes in Evapotranspiration due to Climate Change Figure 42: Simulated Changes in Groundwater Pumping due to Climate Change Figure 43: Eastern San Joaquin Subbasin Projected Agricultural Demand in the PCBL-CC Figure 44: Eastern San Joaquin Subbasin Projected Urban Demand in the PCBL-CC Figure 45: Eastern San Joaquin Subbasin Projected Hydrologic Groundwater Budget Appendices
Appendix A: ESJWRM Version 2.0 Land and Water Use Budgets for each GSA Appendix B: PCBL Version 2.0 Land and Water Use Budgets for each GSA ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 1 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
1 Historical Calibration Update
The Eastern San Joaquin Water Resources Model (ESJWRM) was developed primarily to evaluate the current and recent historical groundwater conditions of the Eastern San Joaquin Groundwater Subbasin (ESJ Subbasin or Subbasin) and simulate various current and future condition scenarios as part of the Groundwater Sustainability Plan (GSP) preparation process under the Sustainable Groundwater Management Act (SGMA) (Woodard & Curran, 2018a). The fine geographic scale of the model provides the opportunity for individual Groundwater Sustainability Agencies (GSAs) to evaluate the effect of changing ESJ Subbasin conditions on smaller GSA areas. The Eastern San Joaquin Groundwater Authority (ESJGWA) was formed by a Joint Powers Agreement (JPA) and coordinates the SGMA activities for the Subbasin. The ESJGWA members include the 16 GSAs in the Subbasin.

ESJWRM uses the Integrated Water Flow Model (IWFM-2015) platform, has a finite element grid, includes data on a monthly time step, and covers the area of Cosumnes Subbasin, Eastern San Joaquin Subbasin, Modesto Subbasin, and the portion of the City of Lathrop east of San Joaquin River in the Tracy Subbasin.

The original development of ESJWRM was from 2016 through 2018, with application of ESJWRM to GSP development occurring from 2018 through 2020 and resulting in a November 2019 GSP (ESJGWA, 2019).

The GSP version of the ESJWRM (ESJWRM Version 1.1), which covers Water Years (WY) 1995 through 2015 (October 1994 through September 30, 2015), was documented in an August 2018 report (Woodard & Curran, 2018a) as well as a February 2018 technical memorandum (Woodard & Curran, 2018b). The earlier reports cover the development of the model, the model platform, the model framework, and all input data and results. This report serves as an update to the earlier model report (Woodard & Curran, 2018a) and only discusses portions of the model that were updated as part of the recent effort to develop ESJWRM Version 2.0, as well as a complete discussion of updated model results. This section includes all the updates made to ESJWRM Version 2.0.

1.1 Model Code and Data Updates Since the Groundwater Sustainability Plan Since the ESJ Subbasin GSP was finalized in November 2019, the ESJWRM has undergone three updates:

1. Extension of Data from Water Year 2016 through Water Year 2019

2. Extension of Data through Water Year 2020

3. Full Model Update and Recalibration (resulting in ESJWRM Version 2.0) The first two updates were completed as part of the preparation of ESJ Subbasin GSP annual reports to the Department of Water Resources (DWR). These updates only included an extension of model time series data (i.e., land use, surface water diversions, groundwater well pumping, and urban demand) and the model provided estimates of total surface water supplies, groundwater pumping, and change in groundwater storage for the water year covered by the model report. The third and major update is the focus of this report and the majority of the work was performed in 2021. Through discussions with GSAs near the completion of the GSP, several areas for update and refinement in the ESJWRM were identified. The goals of the 2021 model update to ESJWRM Version 2.0 were to:

1. Confirm the data in the ESJWRM is the latest hydrologic, water supply, and operations data available. This includes updating issues identified through discussions with the GSAs as part of the GSP process and including newer data and techniques that were unavailable in the development of the original model.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 2 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

2. Refine the model calibration to ensure a reasonable representation of the hydrologic conditions in the ESJ Subbasin with the updated data and observation information.

3. Update the projected conditions baseline to estimate conditions in the ESJ Subbasin at buildout (approximately 2040) without GSP projects and potential climate change conditions. This update is discussed in Section 2.

4. Use the updated ESJWRM versions to develop water budgets at the GSA level to understand the water operations for each GSA to support a water accounting framework and assessment of benefits and impacts of sustainability actions at the GSA level. This is discussed in Section Error! Reference source not found..

The data update was completed through extensive outreach to GSAs and Subbasin agencies and coordination with the ESJGWA Technical Advisory Committee (TAC), including meeting presentations and interaction with stakeholders. Data for the model update included a variety of agencies and GSAs. Below is a list of the agencies that provided data and input on the model update:

Agricultural Water Purveyors
• Calaveras County Water District (CCWD)
• Central San Joaquin Water Conservation District (CSJWCD) • North San Joaquin Water Conservation District (NSJWCD) • Oakdale Irrigation District (OID)
• South San Joaquin Irrigation District (SSJID)
• Stockton East Water District (SEWD)
• Woodbridge Irrigation District (WID)
Municipal Water Purveyors
• California Water Service Company Stockton District (Cal Water) • City of Escalon
• City of Lodi
• City of Manteca
• City of Ripon
• City of Stockton
• Linden County Water District (LCWD)
• Lockeford Community Services District (LCSD)
• Stockton East Water District (SEWD)
For the update to ESJWRM Version 2.0, more extensive coordination was appreciated from the following people:
• Eric Houston (City of Stockton)
• Justin Hopkins (SEWD)
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 3 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
• Mike Henry (LCSD)
• Dave Fletcher (LCWD)
• Alan Nakanishi and Travis Kahrs (City of Lodi)
• Jennifer Spaletta (NSJWCD)
• Eric Thorburn and Emily Sheldon (OID)
• Brandon Nakagawa (SSJID)
• Matt Zidar and Glenn Prasad (San Joaquin County)

1.1.1 IWFM Version
The model platform, IWFM-2015, has had several updates since ESJWRM Version 1.1 was originally developed and the IWFM code has been updated to the latest release version (IWFM-2105 Version 1273) for ESJWRM Version 2.0. New IWFM versions typically include error fixes and larger code changes that may impact the underlying calculations and therefore model results. Changes between model versions are documented on DWR’s IWFM website (https://water.ca.gov/Library/Modeling-and-Analysis/ModelingPlatforms/Integrated-Water-Flow-Model) and the latest IWFM technical memorandums are available online (Dogrul and Kadir, 2021a and 2021b).

1.1.2 Updated Data from the ESJWRM version used in the Stanislaus River Basin Plan A modified version of ESJWRM Version 1.1 was prepared as part of the Stanislaus River Basin Plan. The Stanislaus River Basin Plan, a collaborative effort by Oakdale Irrigation District (OID) and South San Joaquin Irrigation District (SSJID), is still in draft format and is discussed in the respective agricultural water management plans (AWMP) (OID, 2021) (SSJID, 2021). The changes made to the modified version of ESJWRM Version 1.1 were incorporated into the 2021 update to ESJWRM Version 2.0. The changes were focused on Modesto Subbasin and OID, both in ESJ Subbasin and in Modesto Subbasin. Changes included updating agricultural and urban pumping in Modesto Subbasin, surface water diversion and groundwater pumping time series, surface water diversion and groundwater pumping delivery areas for OID and Modesto Subbasin agencies, target soil moisture percentage, agricultural return flow fraction, and Modesto Reservoir seepage. Changes to the Modesto Subbasin are not discussed in detail in the sections below.

1.1.3 Hydrologic Period
The updated ESJWRM Version 2.0 simulates water years 1995 through 2020 (October 1, 1994 through September 30, 2020). It was extended five water years from ESJWRM Version 1.1. Due to the extension of the period covered by the model, all model data with monthly or annual values had to be extended. These updates are listed in the sections below.

1.1.4 Precipitation
As with ESJWRM Version 1.1, rainfall data for the model area is derived from the PRISM (PrecipitationElevation Regressions on Independent Slopes Model) database used in the DWR’s CALSIMETAW (California Simulation of Evapotranspiration of Applied Water) model. The database contains daily precipitation data from October 1, 1921 on a 4-kilometer grid throughout the model area (OSU, 2021). ESJWRM has monthly rainfall data defined for every model element and adjacent foothill watershed in order to preserve the spatial distribution of the monthly rainfall. Each of the model elements was mapped to the nearest of 364 available ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 4 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
PRISM reference nodes, uniformly distributed across the model domain. ESJWRM Version 2.0 includes the mapped precipitation time series for water years 2016 through 2020.

1.1.5 Land Use and Cropping Patterns
ESJWRM Version 2.0 utilizes the same land use categories as ESJWRM Version 1.1 as documented in the earlier reports (Woodard & Curran, 2018a and 2018b). The data through water year 2015 is the same as ESJWRM Version 1.1, except for minor tweaks to land use around the Subbasin’s two smallest GSAs, Lockeford Community Services District (LCSD) and Linden County Water District (LCWD). Due to the small size of these GSAs, model elements did not exactly align with GSA boundaries, so agricultural land use associated with the surrounding districts, North San Joaquin Water Conservation District (NSJWCD) for LCSD and Stockton East Water District (SEWD) for LCWD, was included in elements representing these two small urban communities. In discussions with the GSAs, it was agreed that the agricultural land use would be removed from model elements assigned to LCSD (15 elements) and LCWD (5 elements). In total, this edit impacted an average of 250 acres per year.

DWR released a statewide crop mapping for 2016 that was completed using remote sensing methods to collect and process the data at the parcel scale and was then ground truthed for a high overall accuracy (DWR, 2016). This spatial land use data was mapped to ESJWRM model elements and assumed to represent land use for all extended water years (2016 through 2020). Based on discussions with SSJID and comparison with the most recent AWMP (SSJID, 2021), the 2016 land use for SSJID was replaced with the data for 2015 from ESJWRM Version 1.1.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 5 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 1: 2016 Land Use
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 6 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 2: 2016 Cropping Pattern for ESJ Subbasin

1.1.6 Stream Inflow
Stream inflows to the model were extended using updated data from United States Geological Survey (USGS) stream gages and the United States Army Corps of Engineers (USACE) reservoir releases. Dry Creek, with data estimated using a regression after January 1998, was updated using recent monthly averages for similar water year types. A column was added for SSJID system outflows to Stanislaus River, discussed further in Section 1.1.11 below. A table of stream input data may be found in Table 1.

Table 1: Summary of ESJWRM Stream Inflow Data
Stream Stream
Node Source Gage Name Period of Record
Average
Annual
Streamflow
(acre-feet)
Cosumnes
River 1 USGS
USGS 11335000:

Cosumnes River at
Michigan Bar, CA
October 1907 to
present/ongoing 397,000
Dry Creek 140
USGS
Estimated in C2VSim by
correlation with USGS
11329500: Dry Creek near
Galt, CA
Not continuous
October 1926 to
December 1997
29,000
USGS
Estimated in C2VSim by
correlation with USGS
11335000: Cosumnes River
at Michigan Bar, CA
Used October 1987
to September 1995
and January 1998
to September 2015
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 7 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Stream Stream
Node Source Gage Name Period of Record
Average
Annual
Streamflow
(acre-feet)
n/a
Average of Historical Data
by Month and Water Year
Type
Used October 2015
to present/ongoing
Mokelumne
River 290 USGS
USGS 11323500:

Mokelumne River below
Camanche Dam, CA
October 1904 to
present/ongoing 562,000
Calaveras River 758
USGS
USGS 11308900: Calaveras
River below New Hogan
Dam near Valley Springs,
CA
February 1961 to
September 1990 160,000
USACE New Hogan Dam releases October 1990 to
present/ongoing
Stanislaus River 1033 USGS
USGS 11302000: Stanislaus
River below Goodwin Dam
near Knights Ferry, CA
February 1957 to
present/ongoing 576,000
Tuolumne River 1248 USGS
USGS 11289650: Tuolumne
River below Lagrange Dam
near Lagrange, CA
October 1970 to
present/ongoing 905,000
San Joaquin
River 1497 USGS
USGS 11303500: San
Joaquin River near
Vernalis, CA
October 1923 to
present/ongoing 3,162,000
SSJID System
Outflows to
Stanislaus River
1212 SSJID n/a n/a 24,000

1.1.7 Boundary Conditions
The boundary conditions in the model remain the same as ESJWRM Version 1.1, with eastern flows from the Sierra Nevada Mountains simulated in the model as small watersheds, Camanche Reservoir seepage estimated using a constrained general head boundary condition, Woodward Reservoir and Modesto Reservoir seepage represented as stream diversions, flows from outside of the model area represented with general head boundary conditions, and groundwater levels at or near zero near the edges of the Sacramento-San Joaquin Delta are represented using specified head boundary conditions.

Data was extended through water year 2020 using a monthly average by water year type. Data for water years 2010 through 2015 were recalculated and updated in the model. The heads near the Delta were adjusted based on analysis of nearby observed groundwater levels.

1.1.8 Urban Demand
Urban demand, comprised of annual population and monthly per capita water use (PCWU), is specified for incorporated urban areas or communities and estimated for rural urban demand. Changes to ESJWRM Version 1.1 were to add specified urban areas for Jenny Lind (in Calaveras County with a portion of the city ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 8 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
outside of ESJ Subbasin) and in Modesto Subbasin (Oakdale, Riverbank, Waterford, and Modesto). City of Stockton, which was previously separated into portions for City of Stockton and California Water Service Company Stockton District (Cal Water), was updated to separate out the areas of unincorporated San Joaquin County land from City of Stockton. All urban areas were reviewed and updated to match areas where urban surface water deliveries and urban groundwater pumping was supplied. Urban surface water supply is assumed to have both indoor and outdoor usage, of which excess outdoor use returns to the model streams or percolates into the groundwater system.

Updated population for water years 2016 through 2020 using data from the California Department of Finance (DOF, 2021). The population for the entire Stockton area was updated for the entire model simulation period to data from the California Department of Finance. Based on review by LCSD, LCSD population for the entire model simulation period was updated using historical population and population projections in the 2016 LCSD Municipal Services Review (LCSD, 2016). The rural population, or people not in incorporated areas, was estimated by calculating an estimate of the rural population per acre in San Joaquin County and applying that population estimate to the unincorporated acreage of the model.

Urban demand was calculated for each area as the sum of the surface water (if the agency received surface water) and the groundwater pumping. The updated water supply is discussed in the sections below for surface water (Section 1.1.9) and groundwater (Section 1.1.1). The PCWU was then calculated for each agency as the monthly calculated demand divided by the annual population. Calculating the PCWU directly from the supplied water mitigates issues with urban surplus or shortage in the land and water use budget.

1.1.9 Surface Water Diversions
Surface water diversions were fully reorganized and renumbered in ESJWRM Version 2.0 and many additional diversions were included that were not in ESJWRM Version 1.1. Diversion edits included splitting NSJWCD’s agricultural diversion from Mokelumne River into two time series for the NSJWCD north and south service areas; including NSJWCD recharge projects; refinement of NSJWCD recharge and irrigation schedules; adjustments to Lodi’s data; adding the urban delivery of Calaveras River water from Calaveras County Water District (CCWD) to Jenny Lind (assuming 43% of Jenny Lind lies within ESJ Subbasin); updating OID north and south and SSJID deliveries to better represent what the AWMPs report for farm deliveries, recycled water deliveries, annual contract deliveries, and canal and drain seepage; separating urban deliveries to City of Stockton area into separate time series for City of Stockton, Cal Water, and San Joaquin County users in City of Stockton; separating SEWD diversion losses from Calaveras and Stanislaus Rivers into separate time series; additional diversions to Modesto Subbasin included as part of model refinements for the Stanislaus River Basin Plan; and the update of surface water delivery estimates for areas of the Delta and riparian user areas along the rivers.

All GSAs were provided all model historical supply data to review and update during the development of ESJWRM Version 2.0. Additionally, all surface water diversion delivery groups were reviewed and updated to reflect a more recent understanding of Subbasin surface water operations. A summary of diversions simulated in the model is provided in Table 2, 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). ESJWRM Version 2.0 includes 66 diversions, 61 of which are listed in Table 2 and 5 diversions that are placeholders that are not currently being used in the model. The Projected Conditions Baseline Version 2.0 averages are also included in Table 2 and are discussed in Section 2.1.3.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 9 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Table 2: Summary of ESJWRM Surface Water Deliveries
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
1 Mokelumne River to
North San Joaquin
WCD North System
for Ag
Mokelumne
River
North San
Joaquin WCD
North System
Ag 50% 0% 50% 360 0 NSJWCD
2 Mokelumne River to
North San Joaquin
WCD South System
for Ag
Mokelumne
River
North San
Joaquin WCD
South System
Ag 50% 0% 50% 1,900 2,000 NSJWCD
3 Mokelumne River to
North San Joaquin
WCD for CALFED GW
Recharge Project
Mokelumne
River

CALFED GW
Recharge Project Recharge 100% 0% 0% 260 800 NSJWCD
4 Mokelumne River to
North San Joaquin
WCD For Tracy Lake
Recharge Project
Mokelumne
River
Tracy Lake
Recharge Project Recharge 50% 0% 50% 320 3,200 NSJWCD
5 Mokelumne River to
City of Lodi (by
agreement with
Woodbridge ID) for
M&I
Mokelumne
River City of Lodi Urban 0% 0% 100% 5,500 4,700 Lodi
6 Mokelumne River to
City of Lodi (by
agreement with
NSJWCD) for M&I
Mokelumne
River City of Lodi Urban 0% 0% 100% 370 0 Lodi
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 10 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
7 Mokelumne River to
City of Lodi (banked
from agreement with
WID) for M&I
Mokelumne
River City of Lodi Urban 0% 0% 100% 560 0 Lodi
8 Mokelumne River to
Woodbridge ID for
Ag
Mokelumne
River
Woodbridge
Irrigation District Ag 30% 2% 68% 58,800 44,200 WID
9 Mokelumne River
Export to Contra
Costa WD (by
agreement with
Woodbridge ID)
Mokelumne
River
Export out of
model Urban 0% 0% 100% 2,000 (one
year only) 0 WID
10 Mokelumne River to
City of Stockton for
Delta Water Supply
Project (by
agreement with
Woodbridge ID) for
M&I
Mokelumne
River City of Stockton Urban 0% 0% 100% 7,700 10,500 City of Stockton 11 San Joaquin River at
Empire Tract to City
of Stockton for Delta
Water Supply Project
for M&I
San Joaquin
River City of Stockton Urban 0% 0% 100% 8,500 21,600 City of Stockton 12 Calaveras River to
Bellota Pipeline to
Stockton East WD
WTP for M&I
Calaveras
River
Export out of
model (imported
in Diversions 14,
15, and 16)
Urban 0% 0% 100% 13,800 13,100 SEWD
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 11 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
13 Stanislaus River at
Goodwin Dam to
Farmington Flood
Control Basin to
Lower Farmington
Canal to Peters
Pipeline to Stockton
East WD WTP for
M&I
Import
(outside of

ESJWRM)
Export out of
model (imported
in Diversions 14,
15, and 16)
Urban 0% 0% 100% 29,400 49,900 SEWD
14 Stockton East WD
WTP to City of
Stockton for M&I
Import
(exported in
Diversions 12
and 13)
City of Stockton Urban 0% 0% 100% 18,800 5,100 UWMP
15 Stockton East WD
WTP to Cal Water for
M&I
Import
(exported in
Diversions 12
and 13)
Cal Water Urban 0% 0% 100% 21,800 19,300 UWMP
16 Stockton East WD
WTP to San Joaquin
County in Stockton
for M&I
Import
(exported in
Diversions 12
and 13)
San Joaquin
County in
Stockton
Urban 0% 0% 100% 1,400 1,500 UWMP
17 Calaveras River to
Calaveras County WD
for Ag
Import
(outside of

ESJWRM)
Calaveras County
WD Ag 9% 1% 90% 1,100 1,300 CCWD
18 Calaveras River to
Jenny Lind for M&I
Import
(outside of

ESJWRM)
Jenny Lind Urban 0% 0% 43% 1,800 1,800 CCWD
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 12 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
19 Calaveras River to
Stockton East WD for
Ag
Calaveras
River
Stockton East
Water District Ag 0% 0% 100% 23,600 21,100 SEWD
20 Calaveras River to
Stockton East WD
Losses
Calaveras
River
Stockton East
Water District,
including canals
Recharge 89% 11% 0% 19,300 15,200 SEWD
21 Calaveras River to
Farmington
Groundwater
Recharge Program
Calaveras
River
Farmington
Groundwater
Recharge
Program
Recharge 100% 0% 0% 1,400 5,200 SEWD
22 San Joaquin River to
North Delta for Ag
San Joaquin
River
North Delta
Subregion Ag 5% 1% 94% 139,600 125,800 Estimated by model 23 San Joaquin River to
South Delta for Ag
San Joaquin
River
South Delta
Subregion Ag 5% 1% 94% 26,700 18,500 Estimated by model 24 Stanislaus River at
Goodwin Dam to
Farmington Flood
Control Basin to
Lower Farmington
Canal to Stockton
East WD for Ag
Import
(outside of

ESJWRM)
Stockton East
Water District Ag 0% 0% 100% 4,400 6,800 SEWD
25 Stanislaus River to
Stockton East WD
Losses
Import
(outside of

ESJWRM)
Stockton East
Water District,
including canals
#N/A 88% 12% 0% 900 1,200 SEWD
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 13 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
26 Stanislaus River at
Goodwin Dam to
Farmington Flood
Control Basin via
Little Johns Creek and
Lower Farmington
Canal to Central San
Joaquin WCD for Ag
Import
(outside of

ESJWRM)
Central San
Joaquin WCD Ag 15% 2% 83% 30,000 24,300 SEWD
27 Stanislaus River to
Farmington
Groundwater
Recharge Program
Import
(outside of

ESJWRM)
Farmington
Groundwater
Recharge
Program
Recharge 100% 0% 0% 3,300 4,900 SEWD
28 Stanislaus River at
Goodwin Dam to
Oakdale ID North for
Ag
Import
(outside of

ESJWRM)
Export out of
model (imported
in Diversions 52,
55, and 57)
Ag 0% 0% 0% 98,800 88,000 OID
29 Stanislaus River at
Goodwin Dam to
Oakdale ID South for
Ag [Modesto
Subbasin]
Import
(outside of

ESJWRM)
Export out of
model (imported
in Diversions 53,
54, 56, and 58)
Ag 0% 0% 0% 136,400 121,500 OID
30 Stanislaus River to
Woodward Reservoir
to South San Joaquin
ID for Ag
Import
(outside of

ESJWRM)
Export out of
model (imported
in Diversions 59,
60, and 61)
Ag 0% 0% 0% 189,500 150,000 SSJID
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 14 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
31 Stanislaus River to
Woodward Reservoir
to South San Joaquin
ID Division 6 for Ag
Import
(outside of

ESJWRM)
Export out of
model (imported
in Diversions 59,
60, and 61)
Ag 0% 0% 0% 5,200 7,000 SSJID
32 Woodward Reservoir
Seepage
Import
(outside of

ESJWRM)
Woodward
Reservoir Recharge 100% 0% 0% 17,100 16,000 SSJID
33 Stanislaus River to
Woodward Reservoir
to Nick C. DeGroot
WTP to City of
Manteca for M&I
Import
(outside of

ESJWRM)
City of Manteca Urban 0% 0% 100% 6,800 10,700 UWMP
34 Stanislaus River to
Woodward Reservoir
to Nick C. DeGroot
WTP to City of
Escalon for M&I
Import
(outside of

ESJWRM)
City of Escalon Urban 0% 0% 100% 0 0 UWMP
35 Stanislaus River to
Woodward Reservoir
to Nick C. DeGroot
WTP to City of
Lathrop for M&I
[Tracy Subbasin]
Import
(outside of

ESJWRM)
City of Lathrop Urban 0% 0% 100% 1,400 6,300 UWMP
36 Stanislaus River to
Woodward Reservoir
to Nick C. DeGroot
WTP to City of Ripon
for M&I
Import
(outside of

ESJWRM)
City of Ripon Urban 0% 0% 100% 0 0 UWMP
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 15 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
37 Tuolumne River to
Modesto ID for Ag
[Modesto Subbasin]
Import
(outside of

ESJWRM)
Modesto ID Ag 3% 19% 78% 232,500 196,000
Stanislaus
River Basin
Plan
ESJWRM
Update
38 Tuolumne River to
City of Modesto (via
Modesto ID) for M&I
[Modesto Subbasin]
Import
(outside of

ESJWRM)
Element group
representing City
of Modesto
Urban 3% 1% 96% 30,700 27,100
Stanislaus
River Basin
Plan
ESJWRM
Update
39 Cosumnes River to
Riparian for Ag
[Cosumnes Subbasin]
Cosumnes
River
Riparian diverters
along river Ag 10% 2% 88% 2,800 2,300 C2VSim
40 Dry Creek to Riparian
for Ag [Split Across
Subbasins]
Dry Creek Riparian diverters
along river Ag 10% 2% 88% 5,600 6,400 C2VSim
41 Mokelumne River to
Riparian for Ag
Mokelumne
River
Riparian diverters
along river Ag 10% 2% 88% 9,600 11,300 C2VSim
42 Calaveras River to
Riparian for Ag
Calaveras
River
Riparian diverters
along river Ag 10% 2% 88% 11,400 10,900 C2VSim
43 Stanislaus River to
Riparian for Ag [Split
Across Subbasins]
Stanislaus
River
Riparian diverters
along river Ag 15% 3% 82% 30,600 30,400 C2VSim
44 Tuolumne River to
Riparian for Ag
[Modesto Subbasin]
Tuolumne
River
Riparian diverters
along river Ag 15% 3% 82% 6,100 6,300 C2VSim
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 16 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
45 San Joaquin River to
Riparian for Ag [Split
Across Subbasins]
San Joaquin
River
Riparian diverters
along river Ag 15% 3% 82% 5,800 5,900 C2VSim
46 Modesto ID
Groundwater
Pumping Deliveries
[Modesto Subbasin]
Import
(outside of

ESJWRM)
Modesto ID Ag 0% 0% 100% 21,500 24,300
Stanislaus
River Basin
Plan
ESJWRM
Update
47 Tuolumne River to
Modesto Reservoir
Seepage [Modesto
Subbasin]
Import
(outside of

ESJWRM)
Modesto
Reservoir Recharge 100% 0% 0% 23,000 23,000
Stanislaus
River Basin
Plan
ESJWRM
Update
48 City of Modesto GW
Pumping Deliveries
[Modesto Subbasin]
Import
(outside of

ESJWRM)
City of Modesto Urban 3% 1% 96% 33,100 32,200
Stanislaus
River Basin
Plan
ESJWRM
Update
49 City of Oakdale GW
Pumping Deliveries
[Modesto Subbasin]
Import
(outside of

ESJWRM)
City of Oakdale Urban 3% 1% 96% 4,600 4,800
Stanislaus
River Basin
Plan
ESJWRM
Update
50 City of Waterford GW
Pumping Deliveries
[Modesto Subbasin]
Import
(outside of

ESJWRM)
City of Waterford Urban 3% 1% 96% 1,700 1,500
Stanislaus
River Basin
Plan
ESJWRM
Update
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 17 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
51 City of Riverbank GW
Pumping Deliveries
[Modesto Subbasin]
Import
(outside of

ESJWRM)
City of Riverbank Urban 3% 1% 96% 4,500 4,400
Stanislaus
River Basin
Plan
ESJWRM
Update
52 Farm Deliveries to
Oakdale ID North for
Ag
Import
(exported in
Diversion 28)
Oakdale ID in ESJ
Subbasin Ag 0% 0% 100% 78,900 75,100 OID AWMP
53 Farm Deliveries to
Oakdale ID South for
Ag [Modesto
Subbasin]
Import
(exported in
Diversion 29)
Oakdale ID in
Modesto
Subbasin
Ag 0% 0% 100% 121,000 114,400 OID AWMP
54 Recycled Water to
Oakdale ID South for
Ag [Modesto
Subbasin]
Import
(exported in
Diversion 29)
Oakdale ID in
Modesto
Subbasin
Ag 0% 0% 100% 3,300 3,300 OID AWMP
55 Deliveries to Annual
Contracts by Oakdale
ID North for Ag
Import
(exported in
Diversion 28)
Oakdale ID in ESJ
Subbasin Ag 0% 0% 100% 2,100 2,600 OID AWMP
56 Deliveries to Annual
Contracts by Oakdale
ID South for Ag
[Modesto Subbasin]
Import
(exported in
Diversion 29)
Oakdale ID in
Modesto
Subbasin
Ag 0% 0% 100% 2,300 2,500 OID AWMP
57 Canal and Drain
Seepage in Oakdale
ID North
Import
(exported in
Diversion 28)
Oakdale ID in ESJ
Subbasin Recharge 100% 0% 0% 17,800 17,500 OID AWMP
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 18 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
ID Description Diversion
Location Delivery Area Primary Use
Fraction
ESJWRM
Version 2.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 2.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
58 Canal and Drain
Seepage in Oakdale
ID South [Modesto
Subbasin]
Import
(exported in
Diversion 29)
Oakdale ID in
Modesto
Subbasin
Recharge 100% 0% 0% 18,300 18,000 OID AWMP
59 Farm Deliveries to
South San Joaquin ID
for Ag
Import
(exported in
Diversions 30
and 31)
South San
Joaquin ID Ag 0% 0% 100% 144,000 120,000 SSJID AWMP
60 Direct Diversion from
Main Distributary
Canal to South San
Joaquin ID for Ag
Import
(exported in
Diversions 30
and 31)
South San
Joaquin ID Ag 0% 0% 100% 1,400 0
SSJID
AWMP
61 Main Distributary
Canal and Lateral
Seepage in South San
Joaquin ID
Import
(exported in
Diversions 30
and 31)
South San
Joaquin ID Recharge 90% 10% 0% 33,200 28,200 SSJID AWMP *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) ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 19 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

1.1.10 Groundwater Pumping
Groundwater pumping within ESJWRM is separated into well- or element-based pumping. The former largely includes district-operated wells that feed into the surface water supply network, while the latter includes estimated private groundwater pumping.

Updates to ESJWRM Version 2.0 for well pumping was the addition of Modesto Subbasin wells included in the model updates made for the Stanislaus River Basin Plan and the addition of two OID wells. OID and SSJID district wells were updated to export water out of the model since the district groundwater pumping is included in the farm deliveries to SSJID, OID North, and OID South included as surface water deliveries.

Additionally, all groundwater pumping delivery groups were reviewed and updated to reflect a more recent understanding of Subbasin operations. Table 3 lists the number of wells by type and agency included in ESJWRM.

Element pumping is estimated by IWFM within the model simulation. Element pumping in ESJWRM Version

2.0 was updated to remove all model-calculated groundwater pumping for urban uses in urban areas.

Table 3: Summary of ESJWRM Well Pumping
Agency
Number
of Urban
Pumping
Wells
Number of
Agricultural
Pumping
Wells
Average
Annual
Urban
Pumping
(acre-feet)
Average
Annual
Agricultural
Pumping
(acre-feet)
Cal Water 56 --- 8,200 0
Escalon 4 --- 1,400 0
Lathrop 6 --- 2,200 0
Linden County WD 4 --- 440 0
Lockeford CSD 4 --- 510 0
Lodi 29 --- 13,600 0
Manteca 15 31 9,300 1,300
Oakdale ID* --- 26 0 6,700
Ripon 9 9 3,900 1,000
SEWD 5 --- 590** 0
SSJID --- 28 0 5,200
Stockton 37 --- 8,500 0
Other Modesto
Subbasin Wells --- 246 0 68,000
Total Average Annual Pumping (acre-feet) 48,640 82,200
* Includes wells located both in ESJ Subbasin and Modesto Subbasin ** Average only when wells were active (WY 2015-2020)

1.1.11 Agricultural Operations
Factors that apply to the agricultural operations represented in the model include agricultural return flow fractions, agricultural reuse fractions, and target soil moisture content.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 20 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Both SSJID and OID report large amounts of tailwater as outflow from the districts’ drainage systems in their respective AWMPs (SSJID, 2021) (OID, 2021). For OID, the amount of tailwater from the district lands is represented through adjustments to the return flow fraction, which controls how much of applied water ultimately ends up as drainage to model stream nodes. For SSJID, since the majority of the tailwater ends up back in Stanislaus River the reported system outflows are included as a stream inflow to Stanislaus River below SSJID. The return flow fraction was likewise adjusted for SSJID’s area.

The reuse fraction is the percent of applied water that can be reused as irrigation to meet demand. Based on analysis of the OID 2020 AWMP (OID, 2021), the reuse fraction for OID model elements was set to 2%.

The target soil moisture specifies the fraction of field capacity that IWFM will iterate to and was utilized to adjust OID demand, first in the adjusted version of ESJWRM Version 1.1 prepared for the Stanislaus River Basin Plan and then adjusted based on analysis of the OID 2020 AWMP (OID, 2021).

Canal and drain seepage for the agricultural agencies is included in surface water diversion information and discussed in Section 1.1.9 above. For agencies that may have surface water agreements where a portion of the delivery losses is assumed to occur in the river (e.g., NSJWCD), the interaction between the stream and the groundwater system is simulated separately in ESJWRM and assumed to account for the conveyance losses. This is considered a special case in the operational water budget discussed in Section Error! Reference source not found..

All other files that control agricultural operations were extended through water year 2020 by repeating the recent historical data.

1.2 Calibration Updates and Results
The goals of model calibration are (1) to achieve a reasonable water budget for each component of the hydrologic cycle modeled (i.e., land and water use, soil moisture, stream flow, and groundwater) and (2) to maximize the agreement between simulated and observed groundwater levels at selected well locations and simulated and observed streamflow hydrographs at selected gaging stations. These objectives are achieved through verification of the model input data and adjustment of model parameters.

Due to uncertainty in the model initial conditions, a one year “ramp up” period is included to allow groundwater levels to stabilize. Thus, the model calibration period for the ESJWRM is October 1995 through September 2020 or water years 1996 through 2020 (25 years).

1.2.1 Calibration Process
Model calibration begins after data analysis and input data file development is completed. The calibration effort can be broken down into subsets that align with packages within the IWFM platform. As an integrated groundwater model, the results of each part of the simulation are dependent on one another. The model calibration can be considered a systematic process that includes the following activities:
• Collect data and set calibration targets
• Calibrate land and water use
• Calibrate groundwater system
• Calibrate stream system
• Refine groundwater level calibration using PEST
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 21 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
• Perform sensitivity analysis
• Conduct additional refinements to model as necessary

1.2.1.1 Agricultural Demand Calibration
As part of the calibration of the land and water use budget, root zone parameters are adjusted as needed to achieve reasonable estimates of agricultural demand and to develop the components of a balanced root zone budget. Demand calibration serves as the foundation of the IWFM calibration for agricultural areas, as demand estimated often translates directly to groundwater pumping, which is the primary stress on the groundwater system. To adjust agricultural demand, element-level root zone parameters, particularly the soil hydraulic conductivity, were adjusted in accordance with the hydrologic soil group and area of the model. Soil hydraulic conductivity was adjusted in the areas of the model representing OID North, NSJWCD, and SSJID to better match reported groundwater pumping, demand, and per unit water use.

During agricultural demand calibration, also called root zone calibration, the curve numbers assigned to different land uses were also reviewed. Based on review of percolation of precipitation occurring in different areas of the model, the curve numbers for native and riparian land uses were adjusted. Additionally, refinements were made to the unsaturated zone initial soil moisture to standardize the amount of water in the unsaturated zone from year to year.

1.2.1.2 PEST-Assisted Aquifer Calibration
Aquifer parameter calibration of ESJWRM utilized a parametric grid covering the model area that reflected the scale at which parameters were adjusted throughout the calibration process. The parametric grid, originally adopted from DWR’s California Central Valley Groundwater-Surface Water Simulation Model with coarse grid (C2VSimCG) nodes, was slightly modified to cover the entire ESJWRM model along the boundaries and additional nodes were added or moved within areas of the model to provide better control.

Aquifer parameters included in ESJWRM are horizontal hydraulic conductivity, vertical hydraulic conductivity, specific storage, and specific yield.

Due to the complexities of calibrating an integrated water resources model, a hybrid approach for calibration was utilized to perform a manual calibration on initial water budgets and regional groundwater conditions and a PEST-assisted calibration using PEST (Doherty, 2015) to achieve a refinement of the calibrated parameters that would result in a more accurate simulation. The use of the PEST software package is discussed further in Section 1.2.2.2.

1.2.2 Calibration Verification
ESJWRM was calibrated to local data and information, surface water flows, groundwater hydrographs, and groundwater contours. The sources used to check model results include local knowledge (mainly gathered during TAC meetings), agricultural water management plans, urban water management plans, other local planning efforts, measured groundwater levels, and observed streamflow data.

1.2.2.1 Streamflow Calibration
Streamflow calibration is primarily performed by comparing the simulated streamflow with local observation data for 11 stream gages located on major streams. Data for these gages came from USGS, USACE, or the California Data Exchange Center (CDEC). Two of these stream gages (Mokelumne River below Camanche ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 22 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Dam and San Joaquin River near Vernalis) are duplicates of gages used to estimate stream inflow into the model area and were not referenced for streamflow calibration and only included as verification of the model setup.

Streambed hydraulic conductivity was adjusted during model calibration based on examination of stream flow hydrographs and stream reach water budgets. The portion of Mokelumne River through Camanche Reservoir (Reach 3) was assigned a streambed hydraulic conductivity of zero since all the surface watergroundwater interaction is already represented by the constrained general head boundary condition representing Camanche Reservoir. Additionally, streambed hydraulic conductivities were examined in the overlapping models of DWR’s California Central Valley Groundwater-Surface Water Simulation Model with fine grid (C2VSimFG) and the Cosumnes-South American-North American Integrated Water Resources Model (CoSANA) and adjusted for some corresponding streams.

Simulated stream flows were compared with observed records and exceedance charts were also used to check the model performance when simulating high and low flows at each gage location. Calibration results for select stream gages are included in Figure 3.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 23 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 3: Streamflow Calibration
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 24 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

1.2.2.2 Groundwater Level Calibration
The goal of groundwater level calibration is to achieve the maximum agreement between simulated and observed groundwater elevations at calibration wells while maintaining reasonable values for aquifer parameters. During the calibration of ESJWRM Version 1.1, 70 wells were ultimately selected that were representative of the long-term conditions of groundwater levels both at a local and regional scale in ESJWRM. This same set of calibration points was kept for ESJWRM Version 2.0, with the addition of GSP Representative Monitoring Network wells if they were not already included.

Simulated groundwater levels are calibrated to observed levels through adjustments to hydrogeologic parameters or aquifer parameters including hydraulic conductivity, specific storage, and specific yield. The automated parameter estimation tool, PEST, was used to assist in refinement of aquifer parameters to improve model calibration. PEST-assisted calibration is performed to interact with ESJWRM via input and output files and iteratively modifies parameter values to reduce an objective function representative of the model residual error. These modifications are made within identified bounds of reasonable values for each parameter. PEST-assisted calibration focused on the aquifer parameters such as horizontal and vertical conductivities and storage parameters. Between PEST-assisted calibration iterations, the modeling team revisited the land system and small watershed budgets and made manual adjustments where needed, until calibration goals were met.

The results of the groundwater level calibration indicate that the ESJWRM reasonably simulates the longterm hydrologic responses under various hydrologic conditions. Figure 4 shows a selection of calibration wells with their resulting groundwater level hydrographs showing the updated calibration of ESJWRM Version 2.0. All ESJWRM Version 2.0 groundwater level hydrographs may be downloaded as a Google Earth KMZ file at (Link to be provided).

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 25 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 4: Groundwater Level Calibration
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 26 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
The ESJWRM calibration status was measured using two metrics: the groundwater level trend and the relationship between simulated and observed groundwater levels. The statistics were evaluated to meet the American Standard Testing Method (ASTM) standard. In addition to quantifiable metrics, the ESJWRM calibration was evaluated by generating reasonable regional groundwater flow directions and producing realistic water budgets.

The “Standard Guide for Calibrating a Groundwater Flow Model Application” (ASTM D5981) states that “the acceptable residual should be a small fraction of the head difference between the highest and lowest heads across the site.” The residual is defined as the simulated head minus the observed head. An analysis of all calibration water levels within the model indicated the presence of 200+ feet of water level changes. Using 10 percent as the “small fraction”, the acceptable residual level would be 20 feet. Calibration goals for the groundwater level residuals were set such that no more than 10 percent of the observed groundwater levels would exceed the acceptable residual level of 20 feet.
• 44% of observed groundwater levels are within +/- 5 feet of its respective simulated values • 73% of observed groundwater levels are within +/- 10 feet of its respective simulated values • 96% of observed groundwater levels are within +/- 20 feet of its respective simulated values The residual histogram and scatter plot of simulated versus observed values for the ESJ Subbasin original calibration wells for the calibration period is shown in Figure 5. The scatter plot colors points by input data subregion. The highest elevations are seen in model subregions closer to the foothills (e.g., Subregion 5 and 17).

Figure 5: Calibration Statistics

1.2.3 Sensitivity Analysis
Sensitivity analysis is a way of investigating how sensitive certain model results are to changes in certain model parameters. A sensitive parameter is when the simulation results are greatly affected by changes in ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 27 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
that parameter within its valid range. Conversely, an insensitive parameter means the changes in that parameter within its valid range do not affect the simulation results greatly.

Model parameters that are sensitive can be the largest sources of error and uncertainty when not precisely measured and well understood. For this reason, sensitivity analysis is an important step of the model calibration process. The sensitivity analysis serves the following purposes:
• To improve the understanding of input-output relationships • To quantify the impact of inaccuracies in model parameters • To evaluate the stability and robustness of the model • To understand the overall range of accuracy of the model results For these purposes, the following set of calibration parameters were selected for investigation under ESJWRM sensitivity analysis:
• Aquifer horizontal hydraulic conductivity (Kh) changed globally by factors of 0.5, 0.67, 1.5, 2.0 • Aquifer vertical hydraulic conductivity (Kv) changed globally by factors of 0.5, 0.67, 1.5, 2.0 • Aquitard vertical hydraulic conductivity (Kaqt) changed globally by factors of 0.5, 0.67, 1.5, 2.0 • Specific yield (Sy) changed globally by factors of 0.8, 1.2 • Specific storage (Ss) changed globally by factors of 0.1, 0.2, 5, 10 • Streambed hydraulic conductivity (Kstr) changed globally by factors of 0.2, 0.5, 2.0, 5.0 • Boundary condition conductance for both general and constrained general head (BC_Cond) changed globally by factors of 0.5, 0.67, 1.5, 2.0
• Saturated soil hydraulic conductivity (Ksoil) changed globally by factors of 0.2, 0.5, 2.0, 5.0 • Target soil moisture (TSM) changed globally by setting all values to 0.6 or 0.8 In the process of evaluating the sensitivity of model results to certain parameter changes, the results from the 32 sensitivity runs were analyzed for the ESJ Subbasin and model as a whole and compared to the calibrated model in terms of the groundwater residual statistics. As the changes to the input parameters for sensitivity analysis were made globally, the changes in the model performance were also considered on a global or subregional scale. An improvement in the model performance based on changes in one parameter at a global scale does not necessarily mean improvements in the overall model performance and/or calibration, as the model is calibrated to a number of target parameters, only some of which may be included in the performance assessment during the sensitivity analysis.

Figure 6 presents the relative change in the three groundwater level residual statistics used in the evaluation of model calibration performance for 10 parameters in the entire EJSWRM for the calibration period. These three groundwater level residual statistics are:
• Root mean square error (RMSE): This statistic is a measure of how spread out the residuals are. • Average residual: This statistic measures how inaccurate simulation results are with respect to the corresponding observations on average.
• Correlation coefficient (R2): This statistic is a measure of the strength of the linear relationship between the simulated and observed pairs.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 28 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
In the calibrated model residual statistics shown in Figure 5, the RMSE is 10.12 feet, the average residual is -3.01 feet, and the R2is 0.93. In Figure 6, the impact of the parameter sensitivity on the average residual from the calibration value of -3.01 feet is always too much of an increase or almost no change. In all the runs, the R
2 of 0.93, which ideally would increase in a better calibrated model, either decreases or remains about the same as the calibrated model. Similarly, the RMSE of 10.12 feet would decrease in a better calibrated model; however, all the sensitivity runs either increase or have no impact on the RMSE.

Figure 7 and Figure 8 look at the change in calibration period average ESJ Subbasin change in storage and deep percolation (both parameters from the hydrologic groundwater budget). Both figures show how sensitive change in storage and deep percolation are to changes in parameters, notably aquifer horizontal hydraulic conductivity (Kh), streambed hydraulic conductivity (Kstr), saturated soil hydraulic conductivity (Ksoil), and target soil moisture (TSM). Even relatively minor changes to those parameters can have large impacts on the ultimate model results.

None of the sensitivity runs resulted in a significant improvement in statistics or results. This means that the model is stable and that the calibration is at or near an optimal point when global parameter changes are considered.

Figure 6: Sensitivity of Groundwater Level Residual Statistics in Entire ESJWRM ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 29 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 7: Sensitivity of Change in Groundwater Storage in ESJ Subbasin Figure 8: Sensitivity of Deep Percolation in ESJ Subbasin ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 30 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

1.3 Historical Model Results
A water budget balances supplies, demands, and any subsequent change in storage occurring within the specific portion of the hydrologic cycle. IWFM automatically outputs budgets at the subregion scale for processes involving groundwater, land surface, streams, root zone, small watersheds, and unsaturated zone.

IWFM can output budgets down to a single element or any specific grouping of elements.

During this step of the calibration process, model results are reviewed and summarized into monthly and annual (by water year) budgets. The primary budgets reviewed for calibration are the land and water use budget and the groundwater budget. After extensive budget analysis, key model datasets and parameters are adjusted, particularly groundwater aquifer parameters, to better match local budgets from local agricultural water purveyors and local planning efforts. The ESJWRM Version 2.0 water budget results are summarized in the following sections.

1.3.1 Land and Water Use 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 water demand for the Subbasin within the calibration period was 1,262 thousand acrefeet (TAF), consisting of 1,145 TAF agricultural demand and 117 TAF urban demand. This demand was met by an annual average of 567 TAF of surface water deliveries (512 TAF of agricultural and 55 TAF of urban deliveries) and was supplemented by 699 TAF of groundwater production (638 TAF of agricultural and 62 TAF of urban pumping). The average annual water shortage for the Subbasin within the calibration period was 5 TAF. Of this annual average, all of the surplus is from agricultural excess and the urban shortage is extremely minor at 0.15 TAF. 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. The small agricultural surplus indicates a minor misalignment of demands and supplies likely due to the timing, volume, or delivery location of the supplies. The annual simulated land and water use budgets for the calibration period are presented in Figure 9 and Figure 10 for the Subbasin as a whole, showing the agricultural and urban, respectively, demands and water supplies. If supply and demand do not balance, there is a surplus or shortage indicated on the land and water use budget.

Table 4 shows the annual averages described above for ESJWRM Version 2.0’s calibration period. Compared to ESJWRM Version 1.1 ESJ Subbasin averages, which had a calibration period through 2015 instead of 2020, ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 31 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
the biggest differences in ESJWRM Version 2.0 for the comparable calibration period are in the agricultural land and water use budget. Due to refinements to the agricultural surface water diversions (primarily due to OID, but also due to changes to SSJID, Delta, and riparian diversions), the surface water deliveries increased by 70 TAF compared to ESJWRM Version 1.1. Additional root zone calibration adjusted agricultural demand for several agencies (OID North, NSJWCD, and SSJID), resulting in ESJWRM Version 2.0 having more demand than ESJWRM Version 1.1. The refinement of delivery groups and estimated diversions reduced the surplus in ESJWRM Version 1.1 by 11 TAF, which resulted in less element pumping in ESJWRM Version 2.0. For the urban budget, the refinement of delivery groups (especially for Stockton area urban users), how demand was input into the model, and diversion amounts eliminated the surplus in ESJWRM Version 1.1.

The corresponding land and water use budgets for both agricultural and urban water demands are included for each GSA in Appendix A. OID is separated out into two separate water budgets: North and South. OID North is a GSA and OID South (not a GSA) is part of Modesto Subbasin. LCSD and LCWD do not have any agricultural demand and therefore a figure is not included.

Table 4: Eastern San Joaquin Subbasin Land and Water Use Budget Annual Averages Land and Water Use Budget Component
ESJWRM
Version 2.0
Annual
Average for
WY 1996-
2020
Agricultural Area (thousand acres) 385
Agricultural Demand (TAF) 1,145
Agricultural Groundwater Pumping (TAF) 638
Agricultural Surface Water Deliveries (TAF) 512
Agricultural Surplus (TAF)1 5
Urban Area (thousand acres) 96
Urban Demand (TAF) 117
Urban Groundwater Pumping (TAF) 62
Urban Surface Water Deliveries (TAF) 55
Urban Shortage (TAF)1 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.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 32 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 9: Eastern San Joaquin Subbasin Agricultural Demand Figure 10: Eastern San Joaquin Subbasin Urban Demand
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 33 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

1.3.2 Hydrologic Groundwater Budget
The primary components of the groundwater budget, corresponding to the major hydrologic processes affecting groundwater flow in the ESJ Subbasin, 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) The largest component in the groundwater budget is an average annual 709 TAF of pumping, offset by 262 TAF of deep percolation, a net gain from stream of 129 TAF, 169 TAF of other recharge, and a net boundary inflow of 113 TAF annually. The cumulative change in groundwater storage can be calculated from the change in groundwater storage. The groundwater storage in ESJ Subbasin during the calibration period was an average of 37 TAFY. These averages are shown in Table 5 and the Subbasin annual groundwater budget is shown in Figure 11.

Table 5 shows the annual averages described above for ESJWRM Version 2.0’s calibration period. The average annual change in storage estimation determined using ESJWRM Version 1.1 was 41 TAF. The latest update and calibration of the model to ESJWRM Version 2.0 has refined this estimate to an average annual change in storage of 37 TAF over the extended calibration period through 2020. The difference in these estimates is due in large part to the difference in the calibration period, as well as the overhaul of surface water data, especially with regards to OID, and the update to the overall model calibration. This difference in change in storage is well within the ranges observed in the sensitivity analysis discussed in Section 1.2.3.

Other differences observed in the groundwater budget between ESJWRM Version 2.0 and ESJWRM Version

1.1, using the comparable calibration period, are an increase in deep percolation in ESJWRM Version 2.0, most likely caused by increased applied surface water and changes to the root zone calibration, and a decrease in net stream seepage in ESJWRM Version 2.0 due to changes in groundwater levels near streams caused by other groundwater budget components.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 34 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Table 5: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget Annual Averages Hydrologic Groundwater Budget Component
ESJWRM
Version 2.0
Annual
Average for
WY 1996-2020
Deep Percolation (TAF) 262
Other Recharge (TAF) 169
Net Stream Seepage (TAF) 129
Net Boundary Inflow (TAF) 113
Groundwater Pumping (TAF) 709
Change in Groundwater Storage (TAF) 37
Figure 11: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 35 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
2 Projected Conditions Baseline Update
The refinements and enhancements made to the historical data for the updated historical calibration ESJWRM (ESJWRM Version 2.0) required an update to the projected conditions baseline ESJWRM. The version of the Projected Conditions Baseline (PCBL) presented in the GSP finalized in November 2019 is called PCBL Version 1.0. The updated version of the PCBL using ESJWRM Version 2.0 extended dataset and calibration results is referred to as PCBL Version 2.0. This section presents the key data sources and assumptions used to develop the PCBL Version 2.0 and provides the model results.

The PCBL used to develop the projected water budgets represents estimated long-term hydrologic conditions of the Subbasin under the foreseeable future level of development. The future level of development represents approximately water year 2040 or the closest information available from planning documents.

2.1 Assumptions Used to Develop Projected Conditions Baseline Update This section discusses the assumptions made in converting PCBL Version 1.0 to PCBL Version 2.0. The data and calibration parameters were updated to be consistent with the historical ESJWRM Version 2.0. Initial groundwater levels and soil conditions in the PCBL represent those at the end of the simulation period of the historical ESJWRM Version 2.0 (September 30, 2020).

2.1.1 Hydrology
The GSP version of PCBL Version 1.0 included 50 years of hydrology data from water years 1969 through 2018 (October 1968 through September 30, 2018) and was documented in the ESJ Subbasin GSP (ESJGWA, 2019). The updated version PCBL Version 2.0 uses 52 years of hydrology data from water years 1969 through 2020 (October 1968 through September 30, 2020). The projected 52 years of hydrology used in PCBL Version 2.0 was maintained and extended to meet the SGMA requirements to evaluate how the Subbasin’s surface and groundwater systems may react under representative hydrologic conditions.

2.1.1.1 Precipitation and Hydrologic Water Year Types
Historical precipitation or rainfall in the ESJ Subbasin was used to identify the hydrologic period that would provide a representation of wet, dry, and extreme periods needed for PCBL Version 2.0. Figure 12 shows the Subbasin annual precipitation (blue columns), average precipitation (green line) of approximately 15 inches, and cumulative departure from mean precipitation (orange line) for each water year from 1969 through 2020. This plot represents the spatially-averaged precipitation across ESJ Subbasin elements developed from PRISM precipitation data. The long-term average precipitation is subtracted from annual precipitation within each water year to develop the departure from average precipitation for each water year. Starting at the first year analyzed, the departures are added cumulatively for each subsequent year.

Wet years have a positive departure and upward slopes, dry years have a negative departure and downward slopes, and a year with exactly average precipitation would have zero departure. More severe events are shown by steeper slopes and greater changes.

Each year on the x-axis in Figure 12 is indicated with the San Joaquin Valley Water Year Hydrologic Classification Index published by DWR. The 52 years of the PCBL, from WY 1969 through 2020, represent a range of hydrologic conditions, as identified by the water year types in the San Joaquin Valley Water Year Hydrologic Classification, which classifies water years 1901 through 2020 as Wet (W), Above Normal (AN), ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 36 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Below Normal (BN), Dry (D), and Critical (C) based on inflows to major reservoirs or lakes. A description of how this index is calculated and the specific data used to calculate this index is available online from CDEC at http://cdec.water.ca.gov/cgi-progs/iodir/WSIHIST. In the 52 years of hydrology used in the PCBL Version

2.0, there are 14 Critical years, 9 Dry years, 4 Below Normal years, 7 Above Normal years, and 18 Wet years.

Figure 12: Historical Precipitation in Eastern San Joaquin Subbasin To facilitate assumptions for baseline water supplies and demands, the five San Joaquin Valley water year types were aggregated into three water year type groups. Critical and Dry years are combined into one category in the baseline water year types (called Dry years), Above Normal and Below Normal years are also combined into one category (Normal years), and Wet years remain in one category (called Wet years). With this breakdown, the three baseline water year types have a distribution of 23 Dry years, 11 Normal years, and 18 Wet years. These baseline water year types (Table 6) are used in the remainder of the PCBL data development and results discussion.

As evident in Figure 12, there are three periods of extreme drought in which there are sequences of critical years where the cumulative departure from mean precipitation drops significantly in a steep slope. To capture future extreme dry year periods that may occur in the PCBL, the following 10 water years were designated as Drought periods: 1976-1977, 1987-1992, and 2014-2015. Drought years are highlighted in red on the x-axis of Figure 12 and distinguished in Table 6. Though the most recent drought lasted from 2012 through 2015, the selected baseline drought years only included 2014 and 2015 as those were the most critical years in which supplies and demands were most impacted.

An 11-year period (WY 2010-2020) of historical hydrology was selected to form the basis of projected data developed by averaging recent historical data. This period was selected because of the reliability of the ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 37 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
historical data in ESJWRM Version 2.0 during these years and because the distribution of water year types was relatively consistent with the overall PCBL hydrology.

Table 6: Baseline Hydrologic Water Year Types
Baseline
Year
Water
Year
San Joaquin
Valley Water
Year Hydrologic
Classification
Baseline
Year
Type
Baseline
Year
Water
Year
San Joaquin
Valley Water
Year Hydrologic
Classification
Baseline
Year
Type
1 1969 Wet Wet 27 1995 Wet Wet
2 1970 Above Normal Normal 28 1996 Wet Wet
3 1971 Below Normal Normal 29 1997 Wet Wet
4 1972 Dry Dry 30 1998 Wet Wet
5 1973 Above Normal Normal 31 1999 Above Normal Normal
6 1974 Wet Wet 32 2000 Above Normal Normal
7 1975 Wet Wet 33 2001 Dry Dry
8 1976 Critical Drought 34 2002 Dry Dry
9 1977 Critical Drought 35 2003 Below Normal Normal
10 1978 Wet Wet 36 2004 Dry Dry
11 1979 Above Normal Normal 37 2005 Wet Wet
12 1980 Wet Wet 38 2006 Wet Wet
13 1981 Dry Dry 39 2007 Critical Dry
14 1982 Wet Wet 40 2008 Critical Dry
15 1983 Wet Wet 41 2009 Below Normal Normal
16 1984 Above Normal Normal 42 2010 Above Normal Normal 17 1985 Dry Dry 43 2011 Wet Wet
18 1986 Wet Wet 44 2012 Dry Dry
19 1987 Critical Drought 45 2013 Critical Dry
20 1988 Critical Drought 46 2014 Critical Drought
21 1989 Critical Drought 47 2015 Critical Drought
22 1990 Critical Drought 48 2016 Dry Dry
23 1991 Critical Drought 49 2017 Wet Wet
24 1992 Critical Drought 50 2018 Below Normal Normal
25 1993 Wet Wet 51 2019 Wet Wet
26 1994 Critical Dry 52 2020 Dry Dry
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 38 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

2.1.1.2 Evapotranspiration
No changes to evapotranspiration in ESJ Subbasin were implemented in PCBL Version 2.0. ESJWM Version

2.0 evapotranspiration by land use type and by model subregion is assumed to be consistent into the future.

2.1.1.3 Streamflow
No change was assumed in PCBL Version 2.0 to all stream inflows. SSJID system outflows were calculated based on the 11-year aggregated water year type average of historical data for WY 2010-2020.

2.1.2 Land Use and Cropping Patterns
PCBL Version 2.0 used the latest land use dataset available and incorporated urban buildout to reflect the 2040 land use conditions. Land use and cropping patterns are based on the most recent, comprehensive, and model-wide land use survey from DWR (DWR, 2018d), with adjustments based on local information and input. This spatial land use data was mapped to ESJWRM model elements and is used as the basis of the PCBL as the latest source of reliable land use data covering the entire model domain. The same edits were made to elements representing LCSD and LCWD to remove agricultural land, as described above for ESJWRM Version 2.0 discussed in Section 1.1.5. The land use data for OID area is adjusted to reflect the information consistent with the OID AWMP.

To represent the extent of urban buildout in 2040, the urban areas in 2018 land use dataset were expanded to either the sphere of influence or general plan boundaries and are held constant during the simulation.

The areas with urban buildout are shown in Figure 13 and include Lodi, Stockton, Lathrop, Manteca, Ripon, and Escalon. No growth was assumed for the Jenny Lind urban area. 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 PCBL. Thus, cropping acreage is reduced only where urban expansion occurs. This means that due to projected urban growth of over 48,000 acres, agricultural acreage is expected to decrease by approximately 34,000 acres and undeveloped acreage decreases by under 15,000 acres. Table 7 shows the differences between the DWR 2018 data and the ultimate baseline acreage once urban buildout was incorporated. Figure 14 is a pie chart of the PCBL Version 2.0 cropping pattern.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 39 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 13: 2018 Land Use with Urban Sphere of Influence Boundaries ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 40 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Table 7: ESJ Subbasin Land Use Acreages by Land Use Type Land Use Type DWR 2018
Survey Baseline Model Change from DWR 2018 Survey
Ag Acreage 392,112 358,340 -33,772
Urban Acreage 104,858 153,484 48,625
Undeveloped
Acreage 255,143 240,289 -14,853
Riparian 12,579 12,579 0
Figure 14: 2018 Cropping Pattern for ESJ Subbasin

2.1.3 Water Supply and Demand
Urban water demand in the PCBL Version 2.0 is generally reflective of 2040 conditions. Demand and supply projections were generally available for 2040 or 2045 conditions from urban water management plans (UWMPs). Water demand and supply assumptions are based on the 2020 UWMPs, other planning documents, and the most current information provided by purveyors. Urban demand and supply projections were estimated for three water year types for wet, normal, and dry conditions, with drought periods assumed of critical water supply. Projections for wet years were assumed to be the same as normal conditions when wet year projections were unavailable. After the projected surface water supply and demand were pulled from the planning documents, the projected municipal pumping was calculated as the difference between surface water supply and demand. For the purpose of the modeling, supply was assumed to meet the demand with no surplus.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 41 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Agricultural water supply largely used the 11-year averages of grouped water year types from the recent historical data (WY 2010-2020). All PCBL annual average surface water diversion volumes are included in Table 2.

In each of the drought period years in the PCBL, it was assumed that the surface water supply delivered was at the 2015 level of supply, if lower than the dry year supply. Pumping was increased accordingly if not calculated within the model. In this way, the PCBL is based on the most recent critical year actual historical delivery data and simulates periods of extreme stress on the groundwater system.

2.2 Projected Conditions Baseline Results
This section provides a summary of the ESJWRM PCBL Version 2.0 results.

2.2.1 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 projected water demand for the Subbasin within the 52-year simulation period is 1,258 thousand acre-feet (TAF), consisting of approximately 1,100 TAF expected agricultural demand and 158 TAF expected urban demand. This demand is met by an annual average of 528 TAF of surface water deliveries (453 TAF of agricultural and 76 TAF of urban deliveries) and is supplemented by 743 TAF of groundwater production (661 TAF of agricultural and 82 TAF of urban pumping). Due to uncertainties in the estimation of projected agricultural demand and historical supply records, there is 13 TAF 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 8. The annual land and water use budgets across the ESJ Subbasin are shown in Figure 15 and Figure 16 for the Subbasin as a whole, showing the agricultural and urban, respectively, demands plotted with water supplies.

The corresponding average annual agricultural and urban demand figures for the projected conditions baseline are included for each GSA in Appendix B. As in the historical model LCSD and LCWD do not have projected agricultural demand and therefore the figure is not included. At full buildout to the sphere of ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 42 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
influence boundaries, City of Stockton GSA, San Joaquin County #2, and City of Manteca GSA do not have agricultural demand and therefore figures for those GSAs are also not included.

Table 8: Eastern San Joaquin Subbasin Land and Water Use Budget Annual Average Land and Water Use Budget Component
PCBL
Version 2.0
Annual
Average
Agricultural Area (thousand acres) 359
Agricultural Demand (TAF) 1,100
Agricultural Groundwater Pumping (TAF) 661
Agricultural Surface Water Deliveries (TAF) 453
Agricultural Surplus (TAF)1 13
Urban Area (thousand acres) 153
Urban Demand (TAF) 158
Urban Groundwater Pumping (TAF) 82
Urban Surface Water Deliveries (TAF) 76
Urban Shortage (TAF)1 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.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 43 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 15: Eastern San Joaquin Subbasin Projected Agricultural Demand Figure 16: Eastern San Joaquin Subbasin Projected Urban Demand ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 44 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

2.2.2 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 Version 2.0 remains the largest component in the groundwater budget with an annual average 751 TAF. The PCBL offsets this pumping with 282 TAF of deep percolation, a net gain from stream of 181 TAF, 162 TAF of other recharge, and a total subsurface inflow of 110 TAF 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 the groundwater storage deficit in ESJ Subbasin in the PCBL is 16 TAFY. These annual averages are shown in Table 9. The groundwater budgets, with average cumulative change in storage, are shown for the ESJ Subbasin in Figure

17. Table 9: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget Annual Average Hydrologic Groundwater Budget Component
PCBL
Version 2.0
Annual
Average
Deep Percolation (TAF) 282
Other Recharge (TAF) 162
Net Stream Seepage (TAF) 181
Net Boundary Inflow (TAF) 110
Groundwater Pumping (TAF) 751
Change in Groundwater Storage (TAF) 16
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 45 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 17: Eastern San Joaquin Subbasin Projected Hydrologic Groundwater Budget ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 46 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
3 Projected Conditions Baseline Update with Climate Change With the update of the PCBL Version 2.0, the potential impact of climate change on the Subbasin in the future was also updated. The version of the Projected Conditions Baseline with Climate Change (PCBL-CC) presented in the GSP finalized in November 2019 is called PCBL-CC Version 1.0. The updated version of the PCBL-CC using PCBL Version 2.0 with hydrology perturbation factors is referred to as PCBL-CC Version 2.0.

Largely, PCBL-CC Version 1.0 and Version 2.0 use the same perturbation factors, but PCBL-CC Version 2.0 extends the simulation time period by two years. This section presents the climate change methodology, data sources, and assumptions used to develop the PCBL-CC Version 2.0 and provides the model results.

In PCBL-CC Version 1.0, the ESJGWA decided to use 2070 Central Tendency perturbation factors as a reasonable estimation of the impact of climate change. PCBL-CC Version 2.0 also used 2070 Central Tendency climate change conditions.

3.1 Climate Change Background and Methods
SGMA requires taking into consideration uncertainties associated with climate change in the development of GSPs.

Consistent with Section 354.18(d)(3) and Section 354.18(e) of the GSP Regulations, an analysis was performed for the Subbasin evaluating the projected water budget with and without climate change conditions.

Section 354.18(d)(3) of the GSP Regulations states:
“(d) The Agency shall utilize the following information provided, as available, by the Department pursuant to Section 353.2, or other data of comparable quality, to develop the water budget:
(1) Historical water budget information for mean annual temperature, mean annual precipitation, water year type, and land use.
(2) Current water budget information for temperature, water year type, evapotranspiration, and land use.
(3) Projected water budget information for population, population growth, climate change [emphasis added], and sea level rise.”
Section 354.18(e) states:
“(e) Each Plan shall rely on the best available information and best available science to quantify the water budget for the basin in order to provide an understanding of historical and projected hydrology, water demand, water supply, land use, population, climate change [emphasis added], sea level rise, groundwater and surface water interaction, and subsurface groundwater flow. If a numerical groundwater and surface water model is not used to quantify and evaluate the projected water budget conditions and the potential impacts to beneficial uses and users of groundwater, the Plan shall identify and describe an equally effective method, tool, or analytical model to evaluate projected water budget conditions.”

3.1.1 DWR Guidance
Climate change analysis is an area of continued evolution in terms of methods, tools, forecasted datasets, and the predictions of greenhouse gas concentrations in the atmosphere. The approach developed for this GSP is based on the methodology in DWR’s guidance document (CA DWR, 2018b). The “best available ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 47 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
information” related to climate change in the Eastern San Joaquin Subbasin was deemed to be the information provided by DWR combined with basin-specific modeling tools. The following resources from DWR were used in the climate change analysis:
• SGMA Data Viewer
• Guidance for Climate Change Data Use During Sustainability Plan Development and Appendices (Guidance Document)
• Water Budget BMP
• Climate Change Desktop IWFM Tools
The SGMA Data Viewer contains climate change forecast datasets for download (CA DWR, 2018c). The guidance document details the approach, development, applications, and limitations of the datasets available from the SGMA Data Viewer (CA DWR, 2018c). The Water Budget BMP describes in greater detail how DWR recommends projected water budgets with climate change be estimated (CA DWR, 2016). The Desktop IWFM Tools are available to estimate the projected precipitation and evapotranspiration inputs under climate change conditions (CA DWR, 2018b).

The methods suggested by DWR in the above resources were used, with modifications where needed, to ensure the results would be reasonable for the Eastern San Joaquin Subbasin and align with the assumptions of the ESJWRM. Figure 18 shows the overall process developed for the Subbasin consistent with the Climate Change Resource Guide (CA DWR, 2018b) and describes workflow beginning with projected conditions inputs and assumptions to perturbed 2070 conditions for the projected conditions.

Figure 18: Eastern San Joaquin Climate Change Analysis Process The process described in Figure 18 of developing a projected water budget with and without climate change was discussed with DWR staff and is consistent with the regulations. Further, it enables the analysis to account for variability in demand and supply separate from the uncertainty associated with climate change forecasts.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 48 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Table 10: DWR-Provided DatasetsTable 10 summarizes the forecasted variable datasets provided by DWR that were used to carry out the climate change analysis (CA DWR, 2018b). The Variable Infiltration Capacity (VIC) model referred to in Table 10 is the fully mechanistic hydrologic model used by DWR to derive hydrographs under standard and climate change conditions.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 49 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Table 10: DWR-Provided Datasets
Input Variable DWR-Provided Dataset
Unimpaired Streamflow
Combined VIC model runoff and baseflow to
generate change factors, provided by HUC 8
watershed geometry
Impaired Streamflow (Ongoing
Operations) CalSim II time series outputs
Precipitation VIC model-generated GIS grid with associated change factor time series for each cell
Reference ETo VIC model-generated GIS grid with associated change factor time series for each cell

3.1.2 Climate Change Methodology
Accepted methods for estimating climate change impacts on groundwater are based on the assessment of impacts on the individual water resource system elements that directly link to groundwater. These elements include precipitation, streamflow, evapotranspiration and, for coastal aquifers, sea level rise as a boundary condition. For the Eastern San Joaquin Subbasin, sea level rise was not included.

The method for perturbing the streamflow, precipitation, and evapotranspiration input files is described in the following sections. A future scenario of 2070 climate forecasts was evaluated in this analysis, consistent with DWR guidance (CA DWR, 2018b). 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 (CA DWR, 2018b). The 2070 central tendency among these projections serves to assess impacts of climate change over the long-term planning and implementation period.

Model simulation results reported in the published GSP have been updated in this section using the updated PCBL Version 2.0 completed as part of the 2021 update of the historical and projected conditions model.

This PCBL Version 2.0 has a 52-year simulation baseline period with hydrology from WY 2019 and WY 2020 incorporated. Updates to the PCBL are documented in Section 2. Model results from the updated PCBL-CC are reported in Section 3.3.

3.2 Projected Conditions Baseline with Climate Change Hydrology This section provides a summary of the data sources, methodology, and summarized results of the updates to the hydrology under climate change conditions.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 50 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

3.2.1 Streamflow under Climate Change
Hydrologic forecasts for streamflow under various climate change scenarios are available from DWR as either a flow-based timeseries or a series of perturbation factors applicable to local data. DWR simulates volumetric flow in most regional surface water bodies by utilizing the Water Resource Integrated Modeling System (WRIMS, formally named CalSim II). While river flows and surface water diversions in the Calaveras, San Joaquin, and Stanislaus Rivers are simulated in CalSim II, there are significant variations when compared to local historical data. Due to the uncertainty in reservoir operations, flows from CalSim II provided by the state are not used directly. Instead, relative perturbation factors were used to derive surface water inflows and diversions for use in ESJWRM.

Local tributaries and smaller streams within Eastern San Joaquin Subbasin are not simulated in CalSim II and must be simulated using adjustment factors developed by DWR for unregulated stream systems. Dry Creek flows were perturbed using this method. The resolution of these perturbation factors is at the Hydrologic Unit Code 8 watershed scale. CalSim II model runs are not available for the Mokelumne River, according to Appendix B, Table B-2 of DWR’s Climate Change Document (CA DWR, 2018b). Therefore, Mokelumne River flows used the perturbation factor method for consistency with the methodology applied to smaller streams. The remaining streams simulated in the ESJWRM utilize the IWFM small watershed package, whose climate change impacts are calculated internally dependent on both precipitation and evapotranspiration refinement. Table 11Table 11: Eastern San Joaquin Stream Inflows presents the impaired and unimpaired streams in the ESJWRM for the Eastern San Joaquin Subbasin.

Table 11: Eastern San Joaquin Stream Inflows
Modeled Stream Impaired Unimpaired
Within ESJ Subbasin
Dry Creek X
Mokelumne River X
Calaveras River X
San Joaquin River X
Stanislaus River X
Within Model Area, Outside ESJ Subbasin
Tuolumne River x
Cosumnes River x
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 51 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

3.2.1.1 Unimpaired Flows
Change factors for unimpaired streams (Dry Creek and Mokelumne River) were downloaded from SGMA Data Viewer and multiplied by the projected conditions input streamflow data to calculated perturbed flows.

DWR change factors are available through 2011; however, the model hydrologic period runs from Water Year 1969-2018. Flows for the remaining model years beyond 2011 were synthesized using the change factor from the most recent matching water year type in the available dataset. Water Year types are designated for each year based on the San Joaquin Valley Runoff WY year type index (CA DWR, 2018a).

DWR uses five designations ranging from driest to wettest conditions: Critical, Dry, Below Normal, Above Normal, and Wet. Table 12Table 12: San Joaquin Valley Water Year Type Designations below shows the year type designations used to synthesize the remaining years (2011-2018).

The PCBL with climate change scenario reported in the GSP only used hydrology baseline years through 2018. In the updated PCBL-CC reported in this TM, WY 2019 and WY 2020 are incorporated and added to Table 12 below. The climate change perturbation was carried out for the two additional years of simulation using methods consistent with how the rest of the synthesized years were calculated in the GSP for unimpaired streamflows.

As part of the update to the PCBL, South San Joaquin Irrigation District (SSJID) outflows were incorporated as a new stream inflow to the model. However because these are operationally dependent flows, they were not perturbed in this climate change scenario.

Table 12: San Joaquin Valley Water Year Type Designations Water Year Year Type
2003 Below Normal
2004 Dry
2005 Wet
2006 Wet
2007 Critical
2008 Critical
2009 Below Normal
2010 Above Normal
2011 Wet
2012 Dry
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 52 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
2013 Critical
2014 Critical
2015 Critical
2016 Dry
2017 Wet
2018 Below Normal
2019 Wet
2020 Dry
Figure 19 shows the perturbed time series against the projected conditions scenario time series for Dry Creek through the 52-year simulation period and Figure 20 presents the exceedance probability curve.

Figure 21 and Figure 22 show the same perturbed time series and exceedance curves, but for Mokelumne River. The exceedance curves are provided because they more clearly show the differences between the projected conditions scenario and the with-climate-change scenario. Generally, flows under the climate change scenario are slightly higher.

Figure 19: Dry Creek Hydrograph
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 53 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 20: Dry Creek Exceedance Curve
Figure 21: Mokelumne River Hydrograph
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 54 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 22: Mokelumne River Exceedance Curve

3.2.1.2 Impaired Flows
CalSim II-estimated flows for point locations on the Calaveras River, San Joaquin River, and Stanislaus River were downloaded from DWR. These points obtained from CalSim II include:
• Calaveras River: New Hogan Reservoir Outflow
• San Joaquin River: San Joaquin River at Vernalis
• Stanislaus River: New Melones Reservoir Outflow
These flows represent projected hydrology based on reservoir outflow, operational constraints, and diversions and deliveries of water for the State Water Project and the Central Valley Project. CalSim II data from WY 1969-2003 were available. For the years 2003-2018, streamflow was synthesized based on flows from WY 1969-2003 and the DWR year type index shown in Table 12 (CA DWR, 2018a). For example, the total monthly streamflow for October 2003 was calculated as the average of the monthly streamflows from October 1966 and October 1971 because they are the same water year type.

CalSim II simulated flows were compared with flows generated using the DWR-provided unimpaired perturbation factors. Streamflows simulated in CalSim II and those derived using the unimpaired adjustment factors did not present similar trends, particularly in dry years, due to CalSim II’s simulation of reservoir operations. DWR-provided unimpaired change factors do not account for variations in the operation of the reservoirs that would result from climate change conditions. Therefore, CalSim II outputs were considered a more appropriate starting dataset for regulated streams given that downstream flow is driven by surface water demand rather than natural flow.

The team explored a hybrid approach to improve upon the discrepancy between flows produced using CalSim II and perturbation factors, while accounting for some change in reservoir operations. In this approach, change factors are generated from the difference between the simulated future climate change CalSim II scenario for 2070 climate conditions and a “without climate change” CalSim II run. This “without ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 55 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
climate change” run is the CalSim II 1995 Historical Detrended simulation run. The generated change factors from these two runs were then used to perturb the regulated river inflows simulated in the ESJWRM projected conditions scenario. For the purposes of simplicity, this method is referred to throughout the rest of the document as CalSim II Generated Perturbation Factors (CGPF). The CGPF method presents limitations given that the resulting flows are not directly obtained from an operations model. The actual mass balance on the reservoirs is not tracked in the estimates of the flows and, instead, the method relies on CalSim II tracking storage and managing the reservoir based on the appropriate rule curves.

The climate change perturbation was carried out for the two additional years of simulation using methods consistent with how the rest of the synthesized years were calculated in the GSP for impaired streamflows.

Figure 23 through Figure 28 provide a comparison of project baseline condition and the results of the CGPF method described above for each stream within the ESJ Subbasin, updated for the 52-year simulation.

Figure 29 through Figure 32 show the same hydrographs for streams within the model area, but outside of the ESJ Subbasin. Exceedance curves are included for each of the CGPF flows against the project baseline flows.

Figure 23: Calaveras River Hydrograph
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 56 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 24: Calaveras River Exceedance Curve
Figure 25: Stanislaus River Hydrograph
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 57 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 26: Stanislaus River Exceedance Curve
Figure 27: San Joaquin River Hydrograph
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 58 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 28: San Joaquin River Exceedance Curve
Figure 29: Tuolumne River Hydrograph
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 59 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 30: Tuolumne River Exceedance Curve
Figure 31: Cosumnes River Hydrograph
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 60 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 32: Cosumnes River Exceedance Curve

3.2.2 Precipitation and Evapotranspiration under Climate Change Projected precipitation and evapotranspiration (ETo) change factors were calculated using a climate period analysis based on historical precipitation and ETo from January 1915 to December 2011 (CA DWR, 2018b).

DWR used a macroscale hydrologic model that solves the water balance of a watershed, called the VIC Model. Change factors provided by DWR were calculated as a ratio of the value of a variable under a “future scenario” divided by a baseline. That baseline data is the 1995 Historical Temperature Detrended scenario downscaled from GCM climate data. The “future scenario” corresponds to VIC outputs of the simulation of future conditions using GCM forecasted hydroclimatic variables as inputs. These change factors are thus a simple perturbation factor that corresponds to the ratio of a future with climate change divided by the past without it. Change factors are available on a monthly time step and are spatially defined by the VIC model grid. Supplemental tables with the time series of perturbation factors are available from DWR for each grid cell. DWR has made accessible a Desktop GIS tool for both IWFM and MODFLOW to process these change factors (CA DWR, 2018c).

3.2.2.1 Applying Change Factors to Precipitation
DWR change factors were multiplied by historical precipitation to generate projected precipitation under the 2070 central tendency future scenario using the Desktop IWFM GIS tool (CA DWR, 2018c). The tool calculates an area weighted precipitation change factor for each model grid geometry. This model grid geometry was based on polygons generated around the PRISM nodes within the model region used to specify rainfall depths.

However, the DWR tool only includes change factors through 2011. The remaining 6 years of the time series were synthesized according to historically comparable water years. The perturbation factor from the corresponding month of the comparable year was applied to the baseline of the missing years (2012-2018) to generate projected values. Months with no precipitation in the baseline were assumed to have a monthly ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 61 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
precipitation of 1 mm under climate change to account for increased precipitation that cannot be calculated from a baseline of 0 mm for these synthesized years. The comparable years that were used can be found in Table 13. These comparable years were determined by comparing total San Joaquin Valley runoff, DWR year type index, and total annual Subbasin precipitation.

The same approach reported in the GSP to synthesizing years that are not included in the DWR dataset was used to extend the simulation for two additional years. The comparable water years used to represent WY 2019 and WY 2020 hydrology have been added to Table 13 below.

Table 13: Comparable Water Years (based on Precipitation) Water Year Not
Available in DWR
Tool
Comparable Water
Year
2012 2001
2013 1991
2014 1987
2015 1977
2016 2002
2017 1983
2018 1983
2019 2016
2020 2013
The resulting perturbed precipitation values and the baseline precipitation values for the representative historical period can be found in Figure 33. The exceedance plot for these two times series can be found in Figure 34, both updated for 52 years of projected conditions simulation. The absolute difference between the PCBL-CC and the PCBL are shown in Figure 35.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 62 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 33: Perturbed Precipitation Under Climate Change Figure 34: Perturbed Precipitation Exceedance Curve
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 63 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 35: Subbasin Precipitation Difference with Climate Change Conditions

3.2.2.2 Applying Change Factors to Evapotranspiration
Potential ETo in the Subbasin varies geographically and by land use. The tool provided by DWR to process ETo was not used because of the minimal spatial variation in ETo in the Subbasin. DWR provides change factors for ETo that vary spatially based on the VIC model grid as described above. Change factors for November 1, 1964 through December 1, 2011 were averaged. For the purposes of this analysis, a localized averaged change factor of 1.082 or 1.084 was used depending on the crop type and where in the Subbasin that crop can be found. All ETo in the Subbasin is expected to increase. However, almonds, pistachios, walnuts, cherries, pasture, corn, and rice ETo are expected to increase more with climate change in the South of the Subbasin in comparison to the North. All land uses in the South and the remaining crops in the North are perturbed with a single average change factor of 1.084, as shown for vineyards in Error! Reference source not found..

This average ETo change factor was then applied to the historical ETo time series for each crop type. Because there is currently no interannual variability in ETo in ESJWRM, the same perturbed time series was applied across all simulation years. Refinement to the simulated evapotranspiration of almonds, walnuts, and cherries under 2070 climate conditions is shown in Figure 36 through Figure 38.

There were no changes made to the projected conditions simulation for evapotranspiration in the PCBL model update. Additionally, as is currently set up in the model, there is no variation by year, only by month.

Therefore, there were no adjustments made to the evapotranspiration model input under the projected conditions with climate change scenario while extending the model through the 52 year simulation.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 64 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 36: Monthly Evapotranspiration Variability for Almonds Figure 37: Monthly Evapotranspiration Variability for Walnuts ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 65 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 38: Monthly Evapotranspiration Variability for Cherries Figure 39: Monthly Evapotranspiration Variability for Vineyards ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 66 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

3.3 Projected Conditions Baseline with Climate Change Results This section provides a summary of the ESJWRM PCBL-CC Version 2.0 results.

3.3.1 Differences in Precipitation, Evapotranspiration, and Streamflow under Climate Change
Under the climate change scenario (PCBL-CC), the average annual precipitation is overall 10 percent higher than the projected conditions scenario (PCBL), increasing from 985,000 AFY to 1,082,000 AFY or from about

15.5 in/year to 17.0 in/year. Similarly, the average annual volume of evapotranspiration in PCBL-CC is 8 percent higher than the PCBL, increasing to 1,441,000 AFY from 1,362,000 AFY. Despite there being higher flows in streams in PCBL-CC, the anticipated surface water diversions were not expected to change in PCBLCC due to both availability of water in the stream and water rights agreements limiting diversion months.

With a similar surface water supply and increased water demands under the PCBL-CC, private groundwater production is simulated to increase by approximately 10 percent, from 751,000 AFY to 833,000 AFY. Under climate change conditions, due to increased groundwater use driven by higher agricultural demands, the depletion in aquifer storage is expected to increase by about 134 percent to an average annual storage change of 38,000 AFY in the PCBL-CC, from 16,000 AFY in the PCBL. A graphical representation of simulated changes to precipitation, evapotranspiration, and groundwater pumping are presented in Error! Reference source not found. though Error! Reference source not found.. Full water budgets for the land surface and groundwater systems are discussed in Sections 3.3.2 and 3.3.3.

Figure 40: Simulated Changes in Precipitation due to Climate Change Note: Negative indicates PCBL value was larger and positive indicates PCBL-CC was larger. The climate change scenario largely has more precipitation than the projected conditions scenario.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 67 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 41: Simulated Changes in Evapotranspiration due to Climate Change Note: PCBL-CC evapotranspiration is always larger than the PCBL for all simulated years.

Figure 42: Simulated Changes in Groundwater Pumping due to Climate Change Note: PCBL-CC groundwater pumping is always larger than the PCBL for all simulated years.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 68 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

3.3.2 Land and Water Use 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 projected water demand for the Subbasin within the 52-year simulation period is 1,339 thousand acre-feet (TAF), consisting of approximately 1,181 TAF expected agricultural demand and 158 TAF expected urban demand. This demand is met by an annual average of 528 TAF of surface water deliveries (452 TAF of agricultural and 76 TAF of urban deliveries) and is supplemented by 825 TAF of groundwater production (742 TAF of agricultural and 82 TAF of urban pumping). Due to uncertainties in the estimation of projected agricultural demand and historical supply records, there is 13 TAF 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 14. The annual land and water use budgets across the ESJ Subbasin are shown in Figure 43 and Figure 44 for the Subbasin as a whole, showing the agricultural and urban, respectively, demands plotted with water supplies.

A comparison between the PCBL and the PCBL-CC is included in Table 15. As shown in Section 3.3.1 and Figure 41, evapotranspiration is higher in the PCBL-CC compared to the PCBL in every year of the simulation. This higher evapotranspiration translates to a higher agricultural demand in the PCBL-CC of 81,400 AFY, which must be met by increased groundwater pumping of 81,800 AFY. The slight difference between the demand increase and the groundwater pumping increase is due to a decrease in 400 AFY of agricultural surface water deliveries. Small changes in surface water availability in streams occurred in the PCBL-CC compared to the PCBL due to the impact of perturbation factors on monthly stream flows. On the urban demand side, there were no differences built into the assumptions for climate change for urban entities, so there were no changes to the urban areas in the PCBL-CC versus the PCBL, aside from a minor difference in surface water diversions that was balanced by a small increase in urban shortage.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 69 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Table 14: Eastern San Joaquin Subbasin Land and Water Use Budget Annual Average for

PCBL-CC
Land and Water Use Budget Component

PCBL-CC
Annual
Average
Agricultural Area (thousand acres) 359
Agricultural Demand (TAF) 1,181
Agricultural Groundwater Pumping (TAF) 742
Agricultural Surface Water Deliveries (TAF) 452
Agricultural Surplus (TAF) 13
Urban Area (thousand acres) 153
Urban Demand (TAF) 158
Urban Groundwater Pumping (TAF) 82
Urban Surface Water Deliveries (TAF) 76
Urban Shortage (TAF) 0
Table 15: Eastern San Joaquin Subbasin Land and Water Use Budget Annual Average Comparison Between the PCBL and the PCBL-CC
Annual Average
Land and Water Use Budget
Component PCBL PCBL-CC
Climate Change
Impact (PCBL-CC
minus PCBL)
Agricultural Area (acres) 358,600 358,600 0
Agricultural Demand (AF) 1,099,900 1,181,300 81,400
Agricultural Groundwater Pumping (AF) 660,600 742,400 81,800 Agricultural Surface Water Deliveries (AF) 452,800 452,400 -400 Agricultural Surplus (AF) 13,500 13,500 0
Urban Area (acres) 153,400 153,400 0
Urban Demand (AF) 158,100 158,100 0
Urban Groundwater Pumping (AF) 82,200 82,200 0
Urban Surface Water Deliveries (AF) 75,600 75,500 -100
Urban Shortage (AF) 300 400 100
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 70 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 43: Eastern San Joaquin Subbasin Projected Agricultural Demand in the PCBL-CC Figure 44: Eastern San Joaquin Subbasin Projected Urban Demand in the PCBL-CC ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 71 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022

3.3.3 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-CC remains the largest component in the groundwater budget with an annual average 833 TAF. The PCBL-CC offsets this pumping with 286 TAF of deep percolation, a net gain from stream of 218 TAF, 165 TAF of other recharge, and a total subsurface inflow of 126 TAF annually. 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-CC is 38 TAFY. These annual averages are shown in Table 16. The groundwater budget, with cumulative change in storage, is shown for the ESJ Subbasin in Figure 45.

A comparison of the PCBL and the PCBL-CC is shown in Table 17. The increase in groundwater pumping of 81,800 AFY is due to the increase in evapotranspiration and therefore increased agricultural demand as discussed above in Section 3.3.2 and
Table 15. Additionally, increased precipitation in most years as shown in Error! Reference source not found. and discussed in Section 3.3.1, leads to overall increased deep percolation from precipitation and other recharge (specifically the ungauged watershed drainage component). The increased groundwater pumping causes groundwater levels to be lower, which then causes increased stream seepage, boundary inflow, and change in groundwater storage. The streamflow is overall higher in the PCBL-CC, which may also allow for more stream seepage into the groundwater system.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 72 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Table 16: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget Annual Average Hydrologic Groundwater Budget
Component
PCBL-CC Annual
Average
Deep Percolation (TAF) 286
Other Recharge (TAF) 165
Net Stream Seepage (TAF) 218
Net Boundary Inflow (TAF) 126
Groundwater Pumping (TAF) 833
Change in Groundwater Storage (TAF) 38
Table 17: Eastern San Joaquin Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between the PCBL and the PCBL-CC
Annual Average
Hydrologic Groundwater Budget
Component PCBL PCBL-CC
Climate Change
Impact (PCBL-CC
minus PCBL)
Deep Percolation (AF) 282,100 285,600 3,500
Other Recharge (AF) 161,700 165,300 3,600
Net Stream Seepage (AF) 180,700 218,100 37,400
Net Boundary Inflow (AF) 110,400 126,000 15,700
Groundwater Pumping (AF) 751,300 833,100 81,800
Change in Groundwater Storage (AF) 16,300 38,100 21,800 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 73 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
Figure 45: Eastern San Joaquin Subbasin Projected Hydrologic Groundwater Budget ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 74 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
4 Conclusions and Recommendations
The updated ESJWRM Version 2.0 is a robust, comprehensive, defensible, and well-established model for assessing the water resources in the ESJ Subbasin under historical and projected conditions using PCBL Version 2.0. The following recommendations are to be considered for further refinements and enhancements of the model:
• Continue engagement with local groundwater users and managers. Continue working with local agencies and groundwater users in ESJ Subbasin to further understand the local operations of the groundwater system and improve representation of groundwater users in the ESJWRM. • Enhance variability of potential evapotranspiration. The current version of the IDC used for estimation of the consumptive use of crops in the ESJWRM uses monthly potential ET values that are the same for all years during the model period. Given that there may be annual variability in the potential ET data with possible effects on the annual estimation of crop water demand, it is recommended to use more detailed data with temporal variability to develop a full time series of ET values for use in the model.
• Refine infiltration of precipitation. The current version of the IDC is based on parameters from the DWR C2VSim model. Further refinements can be made to reflect the local soil conditions and rainfall runoff patterns.
• Refine surface water deliveries in Cosumnes Subbasin. The surface water deliveries in the Cosumnes Subbasin are currently at the subregion level and do not have the detailed spatial resolution of other areas within the ESJ Subbasin. This data may be verified and updated with modeling in that subbasin completed to meet the requirements of SGMA. • Update land use as needed. As part of the statewide SGMA support, the DWR prepares statewide land use surveys every other year. It is recommended that the appropriate land use surveys be incorporated in the historical model, as well as the projected baseline as necessary and needed. • Integration with GRAT. ESJGWA is in the process of developing a Groundwater Recharge Assessment Tool (GRAT). It is recommended to integrate the ESJWRM with the GRAT to better assess the implications of any water recharge on the state of the basin and distribution of benefits. • Climate change refinement. The approach developed for the GSP and used in the PCBL-CC Version 2.0 update is based on the methodology in DWR’s guidance document (CA DWR, 2018b) and uses “best available information” related to climate change in the Eastern San Joaquin Subbasin.

There are limitations and uncertainties associated with the analysis. One important limitation is that CalSim II does not fully simulate local surface water operations. Thus, the analysis conducted for this GSP may not fully reflect how surface and groundwater basin operations would respond to the changes in water demand and availability caused by climate change. Mokelumne River flows are simulated in PCBL-CC as unimpaired despite the potential of changes to operations for Pardee and Camanche Reservoirs under climate change conditions. This presents an opportunity in future efforts to improve the analysis to better project streamflow. Use of a local model and the perturbation factor approach were deemed appropriate given the uncertainties in the climate change analysis.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 75 Woodard & Curran, Inc.

Draft ESJWRM Version 2.0 Update June 2022
5 References
California Department of Finance (DOF). Downloaded March 2021. E-4 Population Estimates for Cities, Counties, and the State, 2011-2020 with 2010 Census Benchmark.
https://www.dof.ca.gov/Forecasting/Demographics/Estimates/e-4/2010-21/.

Department of Water Resources. 2016. Best Management Practices for the Sustainable Management of Groundwater Water Budget.

Department of Water Resources (DWR). Statewide Crop Mapping 2016. Downloaded for groundwater subbasins in model area. https://gis.water.ca.gov/app/CADWRLandUseViewer/.

Department of Water Resources (DWR). 2018a. Chronological Reconstructed Sacramento and San Joaquin Valley Water Year Hydrologic Classifications Indices.

Department of Water Resources (DWR). 2018b. Guidance for Climate Change Data Use During Groundwater Sustainability Plan Development.

Department of Water Resources (DWR). 2018c. SGMA Data Viewer.

Department of Water Resources (DWR). 2018d. Statewide Crop Mapping 2018. Downloaded for groundwater subbasins in model area. https://gis.water.ca.gov/app/CADWRLandUseViewer/.

Dogrul, Emin C. and Tariq N. Kadir. 2021a. Integrated Water Flow Model Theoretical Documentation (IWFM2015), Revision 1273. Bay-Delta Office, California Department of Water Resources. September 2021. https://data.cnra.ca.gov/dataset/iwfm-integrated-water-flow-model/resource/64b1047a-39ff-46db-8b93- 1e6f95e50865.

Dogrul, Emin C. and Tariq N. Kadir. 2021b. DWR Technical Memorandum: Theoretical Documentation and User’s Manual for IWFM Demand Calculator (IDC-2015), Revision 1273. Bay-Delta Office, California Department of Water Resources. September 2021. https://data.cnra.ca.gov/dataset/iwfm-integrated-water-flowmodel/resource/64b1047a-39ff-46db-8b93-1e6f95e50865.

Doherty, J., 2015. Calibration and Uncertainty Analysis for Complex Environmental Models. Watermark Numerical Computing, Brisbane, Australia. ISBN: 978-0-9943786-0-6.

Eastern San Joaquin Groundwater Authority (ESJGWA). 2019. Eastern San Joaquin Groundwater Subbasin Groundwater Sustainability Plan. November 2019.

Lockeford Community Services District (LCWD). 2016. Final Lockeford Community Services District Municipal Services Review. Prepared for San Joaquin County Local Agency Formation Commission. September 2016.

Oakdale Irrigation District (OID). 2021. 2020 Agricultural Water Management Plan. Prepared by Davids Engineering. March 2021.

Oregon State University (OSU). Downloaded March 2021. PRISM Climate Group. http://prism.oregonstate.edu.

South San Joaquin Irrigation District (SSJID). 2021. 2020 Agricultural Water Management Plan. Prepared by Davids Engineering. Adopted March 23, 2021.

Woodard & Curran. 2018a. Eastern San Joaquin Water Resources Model (ESJWRM) Final Report. August 2018.

Woodard & Curran. 2018b. Eastern San Joaquin Water Resources Model Agricultural and Urban Demand Estimates Technical Memorandum. February 2018.

ATTACHMENT 2
APPENDIX A: LAND AND WATER USE BUDGETS BY
GSA FOR HISTORICAL MODEL (ESJWRM 2.0)

FIGURES
Figure 1: San Joaquin County #1 GSA Agricultural Demand ..............................................................................................2 Figure 2: San Joaquin County #1 GSA Urban Demand .........................................................................................................2 Figure 3: Central Delta Water Agency GSA Agricultural Demand.....................................................................................3 Figure 4: Central Delta Water Agency GSA Urban Demand................................................................................................3 Figure 5: Woodbridge Irrigation District GSA Agricultural Demand................................................................................4 Figure 6: Woodbridge Irrigation District GSA Urban Demand...........................................................................................4 Figure 7: City of Lodi GSA Agricultural Demand......................................................................................................................5 Figure 8: Cit of Lodi GSA Urban Demand ...................................................................................................................................5 Figure 9: North San Joaquin Water Conservation District GSA Agricultural Demand..............................................6 Figure 10: North San Joaquin Water Conservation District GSA Urban Demand.......................................................6 Figure 12: Lockeford Community Services District GSA Urban Demand .......................................................................7 Figure 13: City of Stockton GSA Agricultural Demand..........................................................................................................7 Figure 14: City of Stockton GSA Urban Demand.....................................................................................................................8 Figure 15: San Joaquin County #2 GSA Agricultural Demand............................................................................................8 Figure 16: San Joaquin County #2 GSA Urban Demand.......................................................................................................9 Figure 17: Stockton East Water District GSA Agricultural Demand..................................................................................9 Figure 18: Stockton East Water District GSA Urban Demand.......................................................................................... 10 Figure 20: Linden County Water District GSA Urban Demand........................................................................................ 10 Figure 21: Central San Joaquin Water Conservation District GSA Agricultural Demand...................................... 11 Figure 22: Central San Joaquin Water Conservation District GSA Urban Demand ................................................. 11 Figure 23: South Delta Water Agency GSA Agricultural Demand.................................................................................. 12 Figure 24: South Delta Water Agency GSA Urban Demand............................................................................................. 12 Figure 25: City of Manteca GSA Agricultural Demand ....................................................................................................... 13 Figure 26: City of Manteca GSA Urban Demand................................................................................................................... 13 Figure 27: South San Joaquin Irrigation District GSA Agricultural Demand .............................................................. 14 Figure 28: South San Joaquin Irrigation District GSA Urban Demand ......................................................................... 14 Figure 29: Oakdale Irrigation District GSA (North) Agricultural Demand................................................................... 15 Figure 30: Oakdale Irrigation District GSA (North)Urban Demand................................................................................ 15 Figure 31: Oakdale Irrigation District GSA (South) Agricultural Demand ................................................................... 16 Figure 32: Oakdale Irrigation District GSA (South) Urban Demand .............................................................................. 16 Figure 33: Eastside San Joaquin GSA Agricultural Demand ............................................................................................. 17 Figure 34: Eastside San Joaquin GSA Urban Demand ........................................................................................................ 17 ATTACHMENT 2
Figure 1: San Joaquin County #1 GSA Agricultural Demand Figure 2: San Joaquin County #1 GSA Urban Demand
ATTACHMENT 2
Figure 3: Central Delta Water Agency GSA Agricultural Demand Figure 4: Central Delta Water Agency GSA Urban Demand
ATTACHMENT 2
Figure 5: Woodbridge Irrigation District GSA Agricultural Demand Figure 6: Woodbridge Irrigation District GSA Urban Demand ATTACHMENT 2
Figure 7: City of Lodi GSA Agricultural Demand
Figure 8: Cit of Lodi GSA Urban Demand
ATTACHMENT 2
Figure 9: North San Joaquin Water Conservation District GSA Agricultural Demand
Figure 10: North San Joaquin Water Conservation District GSA Urban Demand
ATTACHMENT 2
Figure 11: Lockeford Community Services District GSA Urban Demand Figure 12: City of Stockton GSA Agricultural Demand
ATTACHMENT 2
Figure 13: City of Stockton GSA Urban Demand
Figure 14: San Joaquin County #2 GSA Agricultural Demand ATTACHMENT 2
Figure 15: San Joaquin County #2 GSA Urban Demand
Figure 16: Stockton East Water District GSA Agricultural Demand ATTACHMENT 2
Figure 17: Stockton East Water District GSA Urban Demand Figure 18: Linden County Water District GSA Urban Demand ATTACHMENT 2
Figure 19: Central San Joaquin Water Conservation District GSA Agricultural Demand
Figure 20: Central San Joaquin Water Conservation District GSA Urban Demand
ATTACHMENT 2
Figure 21: South Delta Water Agency GSA Agricultural Demand Figure 22: South Delta Water Agency GSA Urban Demand
ATTACHMENT 2
Figure 23: City of Manteca GSA Agricultural Demand
Figure 24: City of Manteca GSA Urban Demand
ATTACHMENT 2
Figure 25: South San Joaquin Irrigation District GSA Agricultural Demand Figure 26: South San Joaquin Irrigation District GSA Urban Demand ATTACHMENT 2
Figure 27: Oakdale Irrigation District GSA (North) Agricultural Demand Figure 28: Oakdale Irrigation District GSA (North)Urban Demand ATTACHMENT 2
Figure 29: Oakdale Irrigation District GSA (South) Agricultural Demand Figure 30: Oakdale Irrigation District GSA (South) Urban Demand ATTACHMENT 2
Figure 31: Eastside San Joaquin GSA Agricultural Demand Figure 32: Eastside San Joaquin GSA Urban Demand
ATTACHMENT 2
APPENDIX B: LAND AND WATER USE BUDGETS BY

GSA FOR PROJECTED CONDITIONS BASELINE MODEL
(PCBL VERSION 2.0)

FIGURES
Figure 1: San Joaquin County #1 GSA Projected Agricultural Demand..........................................................................2 Figure 2: San Joaquin County #1 GSA Projected Urban Demand.....................................................................................2 Figure 3: Central Delta Water Agency GSA Projected Agricultural Demand................................................................3 Figure 4: Central Delta Water Agency GSA Projected Urban Demand...........................................................................3 Figure 5: Woodbridge Irrigation District GSA Projected Agricultural Demand ...........................................................4 Figure 6: Woodbridge Irrigation District GSA Projected Urban Demand ......................................................................4 Figure 7: City of Lodi GSA Projected Agricultural Demand .................................................................................................5 Figure 8: City of Lodi GSA Projected Urban Demand ............................................................................................................5 Figure 9: North San Joaquin Water Conservation District GSA Projected Agricultural Demand .........................6 Figure 10: North San Joaquin Water Conservation District GSA Projected Urban Demand ..................................6 Figure 11: Lockeford Community Services District GSA Projected Urban Demand...................................................7 Figure 12: City of Stockton GSA Projected Urban Demand.................................................................................................7 Figure 13: San Joaquin County #2 GSA Projected Urban Demand ..................................................................................8 Figure 14: Stockton East Water District GSA Projected Agricultural Demand .............................................................8 Figure 15: Stockton East Water District GSA Projected Urban Demand ........................................................................9 Figure 16: Linden County Water District GSA Projected Urban Demand ......................................................................9 Figure 17: Central San Joaquin Water Conservation District GSA Projected Agricultural Demand.................. 10 Figure 18: Central San Joaquin Water Conservation District GSA Projected Urban Demand............................. 10 Figure 19: South Delta Water Agency GSA Projected Agricultural Demand............................................................. 11 Figure 20: South Delta Water Agency GSA Projected Urban Demand ........................................................................ 11 Figure 21: City of Manteca GSA Projected Urban Demand.............................................................................................. 12 Figure 22: South San Joaquin Irrigation District GSA Projected Agricultural Demand.......................................... 12 Figure 23: South San Joaquin Irrigation District GSA Projected Urban Demand..................................................... 13 Figure 24: Oakdale Irrigation District GSA (North) Projected Agricultural Demand............................................... 13 Figure 25: Oakdale Irrigation District GSA (North) Projected Urban Demand.......................................................... 14 Figure 26: Oakdale Irrigation District GSA (South) Projected Agricultural Demand............................................... 14 Figure 27: Oakdale Irrigation District GSA (South) Projected Urban Demand.......................................................... 15 Figure 28: Eastside GSA Projected Agricultural Demand................................................................................................... 15 Figure 29: Eastside GSA Projected Urban Demand.............................................................................................................. 16 ATTACHMENT 2
Figure 1: San Joaquin County #1 GSA Projected Agricultural Demand Figure 2: San Joaquin County #1 GSA Projected Urban Demand ATTACHMENT 2
Figure 3: Central Delta Water Agency GSA Projected Agricultural Demand Figure 4: Central Delta Water Agency GSA Projected Urban Demand ATTACHMENT 2
Figure 5: Woodbridge Irrigation District GSA Projected Agricultural Demand Figure 6: Woodbridge Irrigation District GSA Projected Urban Demand ATTACHMENT 2
Figure 7: City of Lodi GSA Projected Agricultural Demand Figure 8: City of Lodi GSA Projected Urban Demand
ATTACHMENT 2
Figure 9: North San Joaquin Water Conservation District GSA Projected Agricultural Demand
Figure 10: North San Joaquin Water Conservation District GSA Projected Urban Demand
ATTACHMENT 2
Figure 11: Lockeford Community Services District GSA Projected Urban Demand
Figure 12: City of Stockton GSA Projected Urban Demand
ATTACHMENT 2
Figure 13: San Joaquin County #2 GSA Projected Urban Demand Figure 14: Stockton East Water District GSA Projected Agricultural Demand ATTACHMENT 2
Figure 15: Stockton East Water District GSA Projected Urban Demand Figure 16: Linden County Water District GSA Projected Urban Demand ATTACHMENT 2
Figure 17: Central San Joaquin Water Conservation District GSA Projected Agricultural Demand
Figure 18: Central San Joaquin Water Conservation District GSA Projected Urban Demand
ATTACHMENT 2
Figure 19: South Delta Water Agency GSA Projected Agricultural Demand Figure 20: South Delta Water Agency GSA Projected Urban Demand ATTACHMENT 2
Figure 21: City of Manteca GSA Projected Urban Demand
Figure 22: South San Joaquin Irrigation District GSA Projected Agricultural Demand
ATTACHMENT 2
Figure 23: South San Joaquin Irrigation District GSA Projected Urban Demand
Figure 24: Oakdale Irrigation District GSA (North) Projected Agricultural Demand
ATTACHMENT 2
Figure 25: Oakdale Irrigation District GSA (North) Projected Urban Demand Figure 26: Oakdale Irrigation District GSA (South) Projected Agricultural Demand
ATTACHMENT 2
Figure 27: Oakdale Irrigation District GSA (South) Projected Urban Demand Figure 28: Eastside GSA Projected Agricultural Demand
ATTACHMENT 2
Figure 29: Eastside GSA Projected Urban Demand
ATTACHMENT 2
2024
Groundwater Sustainability Plan Amendment
Complete Appendices November 2024
APPENDIX 2-C.

EASTERN SAN JOAQUIN WATER RESOURCES MODEL
(ESJWRM) REPORT VERSION 3.0 UPDATE (2024)
ATTACHMENT 2

Eastern San Joaquin
Water Resources Model
(ESJWRM)
Version 3.0 Update
Prepared for:

Eastern San Joaquin Groundwater Authority
October 2024
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority i Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Table of Contents
SECTION PAGE NO.
1 ACKNOWLEDGEMENTS....................................................................................................................... 1 2 MODEL BACKGROUND........................................................................................................................ 3

2.1 Model Purpose..................................................................................................................................................... 3

2.2 Historical Model Updates ................................................................................................................................ 3

2.3 Model Baseline Scenarios ................................................................................................................................ 4

2.4 Model Platform.................................................................................................................................................... 5

2.5 Model Reporting................................................................................................................................................. 5

2.6 Timeline of Model Development and Updates....................................................................................... 6 3 HISTORICAL CALIBRATION UPDATE ................................................................................................. 8

3.1 Purpose of Historical ESJWRM Version 3.0 Update .............................................................................. 8

3.2 Model Code and Data Updates Since 2022 Revised Groundwater Sustainability Plan Error! Bookmark not defined.

3.2.1 IWFM Version.........................................................................................................................................10

3.2.2 Hydrologic Period.................................................................................................................................10

3.2.3 Precipitation............................................................................................................................................10

3.2.4 Stream Inflow .........................................................................................................................................11

3.2.5 Land Use and Cropping Patterns ...................................................................................................12

3.2.6 Model Layering......................................................................................................................................21

3.2.6.1 Defining Shallow Alluvium Layer...................................................................................22

3.2.6.2 Updating Foothill Layering...............................................................................................23

3.2.6.3 Updating Corcoran Clay Extent......................................................................................23

3.2.6.4 Final Model Layers...............................................................................................................23

3.2.6.5 Comparison of Updated Layers in Previous ESJWRM Versions.........................24

3.2.7 Boundary Conditions...........................................................................................................................29

3.2.8 Urban Demand ......................................................................................................................................29

3.2.9 Surface Water Diversions ..................................................................................................................30

3.2.10 Groundwater Pumping.......................................................................................................................42

3.2.11 Agricultural Operations......................................................................................................................42

3.3 Calibration Updates and Results.................................................................................................................43

3.3.1 Calibration Process...............................................................................................................................43

3.3.1.1 Agricultural Demand Adjustment..................................................................................43

3.3.2 Aquifer Calibration Verification.......................................................................................................44

3.3.3 Sensitivity Analysis ...............................................................................................................................46

3.4 Historical Model Results.................................................................................................................................47

3.4.1 Land and Water Use Budget............................................................................................................47

3.4.2 Hydrologic Groundwater Budget...................................................................................................50 4 PROJECTED CONDITIONS BASELINE UPDATE................................................................................ 52

4.1 Assumptions Used to Develop Projected Conditions Baseline Update ......................................52

4.1.1 Hydrology................................................................................................................................................52

4.1.1.1 Precipitation and Hydrologic Water Year Types......................................................52

4.1.1.2 Evapotranspiration ..............................................................................................................55 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority ii Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024

4.1.1.3 Streamflow..............................................................................................................................55

4.1.2 Land Use and Cropping Patterns ...................................................................................................55

4.1.3 Water Supply and Demand ..............................................................................................................56

4.2 Projected Conditions Baseline Results......................................................................................................56

4.2.1 Land and Water Use Water Budget...............................................................................................57

4.2.2 Hydrologic Groundwater Budget...................................................................................................59 5 PROJECTED CONDITIONS BASELINE UPDATE WITH CLIMATE CHANGE.................................... 61

5.1 Climate Change Background and Methods ...........................................................................................61

5.1.1 DWR Guidance.......................................................................................................................................61

5.1.2 Climate Change Methodology........................................................................................................63

5.2 Projected Conditions Baseline with Climate Change Hydrology ...................................................63

5.2.1 Streamflow under Climate Change ...............................................................................................63

5.2.1.1 Unimpaired Flows ................................................................................................................64

5.2.1.2 Impaired Flows......................................................................................................................68

5.2.2 Precipitation and Evapotranspiration under Climate Change ............................................74

5.2.2.1 Applying Change Factors to Precipitation .................................................................74

5.2.2.2 Applying Change Factors to Evapotranspiration.....................................................76

5.3 Projected Conditions Baseline with Climate Change Results ..........................................................78

5.3.1 Differences in Precipitation, Evapotranspiration, and Streamflow under Climate Change......................................................................................................................................................79

5.3.2 Land and Water Use Budget............................................................................................................81

5.3.3 Hydrologic Groundwater Budget...................................................................................................84 6 PROJECTED CONDITIONS BASELINE SCENARIOS WITH DEMAND REDUCTION ....................... 87

6.1 Assumptions Used to Develop Projected Conditions Baseline Scenarios with Demand Reduction.............................................................................................................................................................87

6.1.1 Projected Conditions Baseline with Demand Reduction ......................................................87

6.1.2 Projected Conditions Baseline with Climate Change and Demand Reduction............91

6.2 Projected Conditions Baseline Scenarios with Demand Reduction Results ..............................94

6.2.1 Projected Conditions Baseline with Demand Reduction ......................................................94

6.2.1.1 Land and Water Use Water Budget..............................................................................95

6.2.1.2 Hydrologic Groundwater Budget..................................................................................98

6.2.2 Projected Conditions Baseline with Climate Change and Demand Reduction......... 100

6.2.2.1 Land and Water Use Water Budget........................................................................... 100

6.2.2.2 Hydrologic Groundwater Budget............................................................................... 103

6.3 Projected Conditions Baseline Scenarios with Demand Reduction Groundwater Level Hydrographs .................................................................................................................................................... 105

6.3.1 Projected Conditions Baseline without and with Demand Reduction ......................... 106

6.3.2 Projected Conditions Baseline with Climate Change and without and with Demand Reduction.............................................................................................................................................. 109

6.3.3 Groundwater Levels Undesirable Result................................................................................... 113 7 PROJECTED CONDITIONS BASELINE SCENARIOS WITH PROJECTS & MANAGEMENT ACTIONS ............................................................................................................................................................ 114

7.1 Category A Projects....................................................................................................................................... 114

7.1.1 SEWD Lake Grupe In-Lieu Recharge.......................................................................................... 115 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority iii Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024

7.1.2 SEWD Surface Water Implementation Expansion................................................................. 116

7.1.3 SEWD Project West Groundwater Recharge Basin............................................................... 117

7.1.4 CSJWCD Capital improvement Program .................................................................................. 118

7.1.5 Long-term Water Transfer to SEWD and CSJWCD............................................................... 119

7.1.6 City of Lodi White Slough Water Pollution Control Facility Expansion................... Error! Bookmark not defined.

7.1.7 NSJWCD South System Modernization ............................Error! Bookmark not defined.

7.1.8 NSJWCD Tecklenburg Recharge Project .................................................................................. 122

7.1.9 NSJWCD South System Groundwater Banking with EBMUD......Error! Bookmark not defined.

7.1.10 NSJWCD North System Modernization/Lakso Recharge ..............Error! Bookmark not defined.

7.1.11 City of Stockton Delta Water Treatment Plant Groundwater Recharge ImprovementsProject...................................................................................................................... 126

7.1.12 NSJWCD Private Pump Partnerships.......................................................................................... 127

7.2 Assumptions Used to Develop Projected Conditions Baseline Scenarios with Projects & Management Actions ................................................................................................................................... 129

7.3 Projected Conditions Baseline Scenarios with Category A Projects & Management Actions Results ................................................................................................................................................................ 133

7.3.1 Projected Conditions Baseline with Category A Projects & Management Actions . 133

7.3.1.1 Land and Water Use Water Budget........................................................................... 133

7.3.1.2 Hydrologic Groundwater Budget............................................................................... 136

7.3.2 Projected Conditions Baseline with Climate Change and Category A Projects and Management Actions....................................................................................................................... 138

7.3.2.1 Land and Water Use Water Budget........................................................................... 138

7.3.2.2 Hydrologic Groundwater Budget............................................................................... 141

7.4 Projected Conditions Baseline Scenarios with Category A Projects & Management Actions Groundwater Level Hydrographs............................................................................................................. 143

7.4.1 Projected Conditions Baseline without and with Category A Projects and Management Actions....................................................................................................................... 143

7.4.2 Projected Conditions Baseline with Climate Change and without and with Category A Projects and Management Actions ........................................................................................ 146

7.4.3 Groundwater Levels Undesirable Result................................................................................... 149 8 CONCLUSIONS AND RECOMMENDATIONS ................................................................................. 150 9 REFERENCES...................................................................................................................................... 152 Tables
Table 1: Summary of ESJWRM Stream Inflow Data in Historical ESJWRM Version 3.0 Table 2: Land Use Categories in Historical ESJWRM Version 3.0 Table 3: Difference between Historical ESJWRM Version 3.0 and Historical ESJWRM Version 2.2 and Earlier Layering
Table 4: Summary of ESJWRM Surface Water Deliveries in Historical ESJWRM Version 3.0 and PCBL Version 3.0
Table 5: Summary of ESJWRM Well Pumping in Historical ESJWRM Version 3.0 Table 6: ESJ Subbasin Land and Water Use Budget Annual Averages of Historical ESJWRM Version 3.0 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority iv Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Table 7: ESJ Subbasin Hydrologic Groundwater Budget of Historical ESJWRM Version 3.0 Table 8: Baseline Hydrologic Water Year Types in PCBL Version 3.0 Table 9: ESJ Subbasin Land Use Acreages by Land Use Type in PCBL Version 3.0 Table 10: ESJ Subbasin Land and Water Use Budget Annual Average of PCBL Version 3.0 Table 11: ESJ Subbasin Hydrologic Groundwater Budget Annual Average of PCBL Version 3.0 Table 12: DWR-Provided Datasets for PCBL-CC Version 3.0 Table 13: ESJWRM Stream Inflows in PCBL-CC Version 3.0
Table 14: San Joaquin Valley Water Year Type Designations Table 15: Comparable Water Years (based on Precipitation) for PCBL-CC Version 3.0 Table 16: ESJ Subbasin Land and Water Use Budget Annual Average for PCBL-CC Version 3.0 Table 17: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between the PCBL Version 3.0 and the PCBL-CC Version 3.0
Table 18: ESJ Subbasin Hydrologic Groundwater Budget Annual Average in PCBL-CC Version 3.0 Table 19: ESJ Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between the PCBL Version 3.0 and the PCBL-CC Version 3.0
Table 20: Agricultural Groundwater Pumping Percent Reduction Comparison Between the GSP Scenario (PCBL-DR Version 1.0) and PCBL-DR Version 3.0
Table 21: Agricultural Groundwater Pumping Percent Reduction Comparison Between the PCBL-CC-DR Version 2.0 and PCBL-CC-DR Version 3.0
Table 22: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL Version

3.0 and PCBL-DR Version 3.0
Table 23: ESJ Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between PCBL Version 3.0 and PCBL-DR Version 3.0
Table 24: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL-CC Version 3.0 and PCBL-CC-DR Version 3.0
Table 25: ESJ Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between the PCBLCC and the PCBL-CC-DR Version 3.0 Table 26: Number of Water Years Out of Total with 2 Consecutive Years of Exceedances Table 27: Summary of ESJWRM Category A Projects Surface Water Deliveries Table 28: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL Version

3.0 and PCBL-PMA Version 3.0
Table 29: ESJ Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between PCBL Version 3.0 and PCBL-PMA Version 3.0
Table 30: ESJ Subbasin Land and Water Use Budget Annual Average Comparison Between PCBL-CC Version 3.0 and PCBL-CC-PMA Version 3.0
Table 31: ESJ Subbasin Hydrologic Groundwater Budget Annual Average Comparison Between the PCBLCC and the PCBL-CC-PMA Version 3.0 Table 32: Number of Water Years Out of Total with 2 Consecutive Years of Exceedances Figures
Figure 1: 1995 Land Use in Historical ESJWRM Version 3.0 Figure 2: 2022 Land Use in Historical ESJWRM Version 3.0 Figure 3: 1995 Grouped Crop Acreage for ESJ Subbasin in Historical ESJWRM Version 3.0 Figure 4: 2022 Grouped Crop Acreage for ESJ Subbasin in Historical ESJWRM Version 3.0 Figure 5: Annual Land Use for ESJ Subbasin in Historical ESJWRM Version 3.0 Figure 6: Annual Grouped Crop Acreage for ESJ Subbasin in Historical ESJWRM Version 3.0 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority v Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 7: Difference between Historical ESJWRM Version 3.0 and Historical ESJWRM Version 2.2 Land Use Acreages by Broad Category
Figure 8: 2022 AEM Survey Lines Above ESJ Subbasin
Figure 9: Example of 3-D Representation of AEM Data with Well Logs Figure 10: North-South Example of Historical ESJWRM Version 3.0 (bottom) and Historical ESJWRM Version 2.2 and Earlier (top) Layering with AEM Coarse Fraction Figure 11: Northern East-West Example of Historical ESJWRM Version 3.0 (bottom) and Historical ESJWRM Version 2.2 and Earlier (top) Layering with AEM Coarse Fraction Figure 12: Southern East-West Example of Historical ESJWRM Version 3.0 (bottom) and Historical ESJWRM Version 2.2 and Earlier (top) Layering with AEM Coarse Fraction Figure 13: Groundwater Level Calibration of Historical ESJWRM Version 3.0 Figure 14: Calibration Statistics of Historical ESJWRM Version 3.0 Figure 15: ESJ Subbasin Agricultural Demand of Historical ESJWRM Version 3.0 Figure 16: ESJ Subbasin Urban Demand of Historical ESJWRM Version 3.0 Figure 17: ESJ Subbasin Hydrologic Groundwater Budget of Historical ESJWRM Version 3.0 Figure 18: Historical Precipitation in ESJ Subbasin in PCBL Version 3.0 Figure 19: 2022 Grouped Crop Acreage for ESJ Subbasin in PCBL Version 3.0 Figure 20: ESJ Subbasin Projected Agricultural Demand of PCBL Version 3.0 Figure 21: ESJ Subbasin Projected Urban Demand of PCBL Version 3.0 Figure 22: ESJ Subbasin Projected Hydrologic Groundwater Budget of PCBL Version 3.0 Figure 23: ESJWRM Climate Change Analysis Process for PCBL-CC Version 3.0 Figure 24: Dry Creek Hydrograph for PCBL-CC Version 3.0 Figure 25: Dry Creek Exceedance Curve for PCBL-CC Version 3.0 Figure 26: Mokelumne River Hydrograph for PCBL-CC Version 3.0 Figure 27: Mokelumne River Exceedance Curve for PCBL-CC Version 3.0 Figure 28: Calaveras River Hydrograph for PCBL-CC Version 3.0 Figure 29: Calaveras River Exceedance Curve for PCBL-CC Version 3.0 Figure 30: Stanislaus River Hydrograph for PCBL-CC Version 3.0 Figure 31: Stanislaus River Exceedance Curve for PCBL-CC Version 3.0 Figure 32: San Joaquin River Hydrograph for PCBL-CC Version 3.0 Figure 33: San Joaquin River Exceedance Curve for PCBL-CC Version 3.0 Figure 34: Tuolumne River Hydrograph for PCBL-CC Version 3.0 Figure 35: Tuolumne River Exceedance Curve for PCBL-CC Version 3.0 Figure 36: Cosumnes River Hydrograph for PCBL-CC Version 3.0 Figure 37: Cosumnes River Exceedance Curve for PCBL-CC Version 3.0 Figure 38: Perturbed Precipitation Under Climate Change for PCBL-CC Version 3.0 Figure 39: Perturbed Precipitation Exceedance Curve for PCBL-CC Version 3.0 Figure 40: Subbasin Precipitation Difference with Climate Change Conditions for PCBL-CC Version 3.0 Figure 41: Monthly Evapotranspiration Variability for Almonds for PCBL-CC Version 3.0 Figure 42: Monthly Evapotranspiration Variability for Walnuts for PCBL-CC Version 3.0 Figure 43: Monthly Evapotranspiration Variability for Cherries for PCBL-CC Version 3.0 Figure 44: Monthly Evapotranspiration Variability for Vineyards for PCBL-CC Version 3.0 Figure 45: Simulated Changes in Precipitation due to Climate Change in PCBL-CC Version 3.0 Figure 46: Simulated Changes in Evapotranspiration due to Climate Change in PCBL-CC Version 3.0 Figure 47: Simulated Changes in Groundwater Pumping due to Climate Change in PCBL-CC Version 3.0 Figure 48: ESJ Subbasin Projected Agricultural Demand in the PCBL-CC Version 3.0 Figure 49: ESJ Subbasin Projected Urban Demand in the PCBL-CC Version 3.0 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority vi Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 50: ESJ Subbasin Projected Hydrologic Groundwater Budget in PCBL-CC Version 3.0 Figure 51: ESJWRM Elements in ESJ Subbasin not Within 1-Mile Buffer of the Major Streams for PCBL-DR and PCBL-CC-DR
Figure 52: Agricultural Groundwater Pumping Density for PCBL Version 3.0 Figure 53: Agricultural Groundwater Pumping Density for PCBL-DR Version 3.0 Figure 54: Agricultural Groundwater Pumping Density for PCBL-CC Version 3.0 Figure 55: Agricultural Groundwater Pumping Density for PCBL-CC-DR Version 3.0 Figure 56: ESJ Subbasin Projected Agricultural Demand in PCBL-DR Version 3.0 Figure 57: ESJ Subbasin Projected Urban Demand in PCBL-DR Version 3.0 Figure 58: ESJ Subbasin Projected Hydrologic Groundwater Budget in PCBL-DR Version 3.0 Figure 59: ESJ Subbasin Projected Agricultural Demand in the PCBL-CC-DR Version 3.0 Figure 60: ESJ Subbasin Projected Urban Demand in the PCBL-CC-DR Version 3.0 Figure 61: ESJ Subbasin Projected Hydrologic Groundwater Budget in the PCBL-CC-DR Version 3.0 Figure 62: ESJ Subbasin Groundwater Level Representative Monitoring Well Locations Figure 63: Groundwater Level Representative Monitoring Network Wells with MT Exceedances in PCBL Version 3.0
Figure 64: Groundwater Level Representative Monitoring Network Wells with MT Exceedances in PCBL-DR Version 3.0
Figure 65: Groundwater Level Hydrograph for Well 01S10E04C001 Figure 66: Groundwater Level Representative Monitoring Network Wells with MT Exceedances in the PCBL-CC Version 3.0
Figure 67: Groundwater Level Representative Monitoring Network Wells with MT Exceedances in the PCBL-CC-DR Version 3.0
Figure 68: Groundwater Level Hydrograph for Well Swenson-3 Figure 69: Number of Wells with 2 Consecutive Water Years of Exceedances Figure 70: General Location of Category A Projects
Figure 71: ESJ Subbasin Projected Agricultural Demand in PCBL-PMA Version 3.0 Figure 72: ESJ Subbasin Projected Urban Demand in PCBL-PMA Version 3.0 Figure 73: ESJ Subbasin Projected Hydrologic Groundwater Budget in PCBL-PMA Version 3.0 Figure 74: ESJ Subbasin Projected Agricultural Demand in the PCBL-CC-PMA Version 3.0 Figure 75: ESJ Subbasin Projected Urban Demand in the PCBL-CC-PMA Version 3.0 Figure 76: ESJ Subbasin Projected Hydrologic Groundwater Budget in the PCBL-CC-PMA Version 3.0 Figure 77: Groundwater Level Representative Monitoring Network Wells with MT Exceedances in PCBLPMA Version 3.0 Figure 78: Groundwater Level Hydrograph for Well 01S10E04C001 Figure 79: Groundwater Level Representative Monitoring Network Wells with MT Exceedances in the PCBL-CC-PMA Version 3.0
Figure 80: Groundwater Level Hydrograph for Well Swenson-3 Figure 81: Number of Wells with 2 Consecutive Water Years of Exceedances ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 1 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
1 Acknowledgements
The development of Eastern San Joaquin Water Resources Model (ESJWRM or Model) over the years has involved a lot of stakeholders in Eastern San Joaquin Groundwater Subbasin (ESJ Subbasin or Subbasin), notably members of local Groundwater Sustainability Agencies (GSAs) and the Eastern San Joaquin Groundwater Authority (ESJGWA). All work on the ESJWRM Version 3.0 model update was presented to members of the ESJGWA’s Project Management Committee (PMC). Individual GSAs were not consulted directly during this model update, but are listed below as providing data and support to the model over the years.

ESJGWA’s Project Management Committee (PMC)
• Ashley Couch, Water Resources Manager of San Joaquin County • Justin Hopkins, General Manager of Stockton East Water District (SEWD) • Mitch Maidrand, Deputy Director of the Municipal Utilities Department of City of Stockton • Scot Moody, General Manager of Oakdale Irrigation District (OID) • Brandon Nakagawa, Water Resources Coordinator of South San Joaquin Irrigation District (SSJID) • Steve Schwabauer, General Manager of North San Joaquin Water Conservation District (NSJWCD) • Alternate: Andrew Watkins, SEWD Board Member
• Alternate: Hope Paulin, San Joaquin County Water Resources Agricultural Water Purveyors
• Calaveras County Water District (CCWD)
• Central San Joaquin Water Conservation District (CSJWCD) • North San Joaquin Water Conservation District (NSJWCD) • Oakdale Irrigation District (OID)
• South San Joaquin Irrigation District (SSJID)
• Stockton East Water District (SEWD)
• Woodbridge Irrigation District (WID)
Municipal Water Purveyors
• California Water Service Company Stockton District (Cal Water) • City of Escalon
• City of Lodi
• City of Manteca
• City of Ripon
• City of Stockton
• Linden County Water District (LCWD)
• Lockeford Community Services District (LCSD)
• Stockton East Water District (SEWD)
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 2 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Woodard & Curran has served as the primary consultant in charge of updating, maintaining, calibrating, running, and processing the model results for ESJWRM since it was developed.

Woodard & Curran 2024 Project Team Working on ESJWRM Version 3.0 Update • Ali Taghavi
• Dalia Portillo
• Emily Honn
• Katie Cole
• Leslie Dumas
• Liz DaBramo
• Nicole Koerth
• Sara Miller
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 3 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
2 Model Background
This section includes a history of the Eastern San Joaquin Water Resources Model (ESJWRM or Model) development and application and information on the model platform driving the calculations within ESJWRM. The ESJWRM is an integrated water resources model that simulates the surface water and groundwater conditions in the Eastern San Joaquin Groundwater Subbasin (ESJ Subbasin or Subbasin), and is developed to evaluate the recent historical, current, and estimated projected future groundwater conditions in the Subbasin. Additionally, the Model is developed to simulate projects and management actions, land and water use, and water demand and water supply scenarios under historical, current, and projected conditions, as part of the Groundwater Sustainability Plan (GSP) process to meet the Sustainable Groundwater Management Act (SGMA) regulatory requirements. The fine geographic scale of the model provides the opportunity for individual Groundwater Sustainability Agencies (GSAs) to evaluate the effect of changing conditions on local areas. The Eastern San Joaquin Groundwater Authority (ESJGWA) was formed by a Joint Powers Agreement (JPA) and coordinates the SGMA activities for the Subbasin. Various committees of the ESJGWA were involved in the development and subsequent applications of the ESJWRM.

Specific information about the ESJWRM can be found in later sections.

2.1 Model Purpose
ESJWRM is a decision-making tool for the ESJ Subbasin. It can have various uses, including:
• Developing understanding of Subbasin inflows, outflows, and change in storage under variety of conditions and planning horizons (historical, current, future) • Understanding of current and historical groundwater storage and depletions of interconnected surface water
• Estimating Subbasin sustainable yield
• Evaluating impact of demand reduction on Subbasin sustainability • Evaluating impact of climate change on Subbasin sustainability • Developing or evaluating Sustainable Management Criteria (SMC) for groundwater levels, groundwater storage, and depletions of interconnected surface water • Evaluating projects and management actions needed to reach sustainability • Providing information on Subbasin data gaps or focus needs

2.2 Historical Model Updates
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 2019 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
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 4 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024

5. Extension of Data in Historical ESJWRM Version 2.0 through WY 2021 for WY 2021 Annual Report

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
The original development of the Historical ESJWRM was completed in 2018, with application of ESJWRM for GSP development resulting in a November 2019 GSP (ESJGWA, 2019). The GSP version of the Historical ESJWRM (Historical ESJWRM Version 1.1) covers Water Years (WY) 1995 through 2015 (October 1, 1994 through September 30, 2015) and was documented in an August 2018 report (Woodard & Curran, 2018a) as well as a February 2018 technical memorandum (Woodard & Curran, 2018b). Historical ESJWRM Version

1.1 calibrated through WY 2015 was extended for the WY 2019 Annual Report and WY 2020 Annual Reports (ESJGWA, 2020; ESJGWA, 2021).

In 2021, the Historical ESJWRM was updated and recalibrated for the entire model period of record from WY 1996 through 2020. Updates to the model (Historical ESJWRM Version 2.0) are described in a 2022 report (Woodard & Curran, 2022a). Historical ESJWRM Version 2.0 was used in revisions to the GSP completed in 2022 (ESJGWA, 2022b). The time series for Historical ESJWRM Version 2.0 was extended through WY 2021 for the WY 2021 Annual Report (ESJGWA, 2022a). In late 2022, the monthly agricultural demand distribution for Historical ESJWRM was updated in select areas of the groundwater subbasin, causing slight changes to water budget numbers, but minimal differences to overall model calibration. This version, Historical ESJWRM Version 2.2, was the basis for two time series extensions through WY 2022 and WY 2023 for the WY 2022 and WY 2023 Annual Reports, respectively (ESJGWA, 2023; ESJGWA, 2024).

In 2024, the Historical ESJWRM Version 3.0 was updated and recalibrated for the entire model period of record from WY 1996 through 2023. Major changes included the revision of model layers, update of land use data, simulation of local reservoir seepage, and adjustments to surface water delivery data to several Subbasin agricultural agencies based on recent local information. This version, Historical ESJWRM Version

3.0, represents the latest base version of the historical model, which has an updated calibration for WY 1996 through 2023 and, as of this report, contains updated data through WY 2023. ESJWRM is planned to be the primary numerical model for assessment of subbasin sustainability, and as such will be maintained and updated annually for the GSP Annual Report preparation and to continue to analyze implementation and sustainability periods for the Subbasin.

2.3 Model Baseline Scenarios
The Historical ESJWRM has been the basis for other model scenarios, notably the ESJWRM Projected Conditions Baseline (PCBL). The PCBL Version 3.0 uses 55 years of hydrology data from WY 1969 through 2023 (October 1, 1968 through September 30, 2023). The PCBL represents estimated long-term hydrologic conditions of the Subbasin under the foreseeable future level of development. The future level of development represents approximately water year 2040 or the closest information available from planning documents and assumes urban buildout consistent with general plan or sphere of influence boundaries.

The six baseline scenarios are listed below:
• Projected Conditions Baseline (PCBL)
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 5 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
• Projected Conditions Baseline with Demand Reduction (PCBL-DR) • Projected Conditions Baseline with Category A Projects & Management Actions (PCBL-PMA) • Projected Conditions Baseline with Climate Change (PCBL-CC) • Projected Conditions Baseline with Climate Change and Demand Reduction (PCBL-CC-DR) • Projected Conditions Baseline with Climate Change and Category A Projects & Management Actions (PCBL-CC-PMA)
The Current Conditions Baseline (CCBL) was previously a separate model scenario that was developed for the GSP but not maintained in the years and updates to the model since. Moving forward, the CCBL will represent a recent historical average and will be more consistent with the data reported in each Annual Report. In addition to these scenarios, the model was used for additional analysis in the 2024 GSP Amendment related to interconnected-surface water, groundwater storage, and achieving groundwater level sustainability.

2.4 Model Platform
The model platform, IWFM-2015, is maintained by the California Department of Water Resources (DWR).

IWFM-2015 has had several updates since ESJWRM Version 1.1 was originally developed and the IWFM code was updated to the latest release version (IWFM-2015 Version 1443) at the time of Historical ESJWRM Version 3.0 development. New IWFM versions typically include error fixes and larger code changes that may impact the underlying calculations and therefore model results. Changes between model versions are documented on DWR’s IWFM website (https://water.ca.gov/Library/Modeling-and-Analysis/ModelingPlatforms/Integrated-Water-Flow-Model) and the IWFM technical memorandums corresponding to Version 1443 are available online (Dogrul and Kadir, 2024a and 2024b).

The root zone simulation package of IWFM is called IWFM Demand Calculator (IDC) and can either be standalone or linked with IWFM. ESJWRM used the linked version of IDC for its root zone package. IDC is available on DWR’s IDC website (https://water.ca.gov/Library/Modeling-and-Analysis/ModelingPlatforms/Integrated-Water-Flow-Model-Demand-Calculator) and the IDC technical memorandum is available online (Dogrul and Kadir, 2021c). The technical memorandums for IWFM and IDC include the equations that govern the flows simulated in IWFM models.

2.5 Model Reporting
The original development of ESJWRM was from 2016 through 2018, with application of ESJWRM to GSP development occurring from 2018 through 2020 and resulting in a November 2019 GSP (ESJGWA, 2019).

The GSP version of the ESJWRM (ESJWRM Version 1.1), which covers Water Years (WY) 1995 through 2015 (October 1994 through September 30, 2015), was documented in an August 2018 report (Woodard & Curran, 2018a) as well as a February 2018 technical memorandum (Woodard & Curran, 2018b). The earlier reports cover the development of the model, the model platform, the model framework, and all input data and results. The 2022 model update report served as an update to the earlier model report (Woodard & Curran, 2018a) and only discussed portions of the model that were updated as part of the effort to develop Historical ESJWRM Version 2.0, PCBL Version 2.0, and PCBL-CC Version 2.0 (Woodard & Curran, 2022a).

Additional documentation developed at the time as part of the 2022 Revised GSP included separate technical memoranda on ESJWRM baseline scenarios for Demand Reduction and Projects & Management Actions (Woodard & Curran, 2022b; Woodard & Curran, 2022c). These memoranda are included in this report in full and have been updated from the earlier versions. Similar to the 2022 report, this report serves ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 6 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
as an update to the earlier model report (Woodard & Curran, 2018a; Woodard & Curran, 2022a) and only discusses portions of the model that were updated as part of the recent effort to develop ESJWRM Version

3.0 and all related scenarios.

2.6 Timeline of Model Development and Updates
Below is the timeline, complete through October 2024, of all modeling activities related to ESJWRM:
• September 2016-January 2019: Development and calibration of Historical ESJWRM (Woodard & Curran, 2018a; Woodard & Curran, 2018b)
o Historical ESJWRM Version 1.1 (WY 1995-2015)
• March 2018-May 2019: Development of GSP scenarios (all use 50 years of hydrologic data: WY 1969-2018) (ESJGWA, 2019)
o Current Conditions Baseline (CCBL) Version 1.0
o PCBL Version 1.0
o PCBL-DR Version 1.0
o PCBL-CC Version 1.0
• March 2020: Historical model extension for GSP Annual Report (ESJGWA, 2020) o Historical ESJWRM Version 1.2 (WY 1995-2019)
• March 2021: Historical model extension for GSP Annual Report (ESJGWA, 2021) o Historical ESJWRM Version 1.3 (WY 1995-2020)
• July 2021-January 2022: Update and recalibration of Historical ESJWRM (WY 1995-2020) (Woodard & Curran, 2022a)
o Historical ESJWRM Version 2.0 (WY 1995-2020)
• March 2022: Historical model extension for GSP Annual Report (ESJGWA, 2022a) o Historical ESJWRM Version 2.0 (WY 1995-2021)
• January 2022-May 2022: Updates to scenarios for revised GSP based on updates to Historical ESJWRM Version 2.0 (all use 52 years of hydrologic data: WY 1969-2020) o PCBL Version 2.0 (Woodard & Curran, 2022a)
o PCBL-DR Version 2.0 (Woodard & Curran, 2022c)
o PCBL-CC Version 2.0 (Woodard & Curran, 2022a)
o PCBL-CC-DR Version 2.0 (Woodard & Curran, 2022c)
o PCBL-PMA Version 2.0 (Woodard & Curran, 2022b)
o PCBL-CC-PMA Version 2.0 (Woodard & Curran, 2022b)
• September 2022-December 2022: Updates to monthly agricultural demand distribution for Historical ESJWRM
o Historical ESJWRM Version 2.2 (WY 1995-2020)
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 7 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
• January 2023: Updates to PCBL based on monthly agricultural demand distribution made in Historical ESJWRM Version 2.2 (52 years of hydrologic data: WY 1969-2020) o PCBL Version 2.1
• March 2023: Historical model extension for GSP Annual Report (ESJGWA, 2023) o Historical ESJWRM Version 2.2 (WY 1995-2022)
• March 2024: Historical model extension for GSP Annual Report (ESJGWA, 2024) o Historical ESJWRM Version 2.2 (WY 1995-2023)
• December 2023-May 2024: Update and recalibration of Historical ESJWRM (WY 1995-2023) o Historical ESJWRM Version 3.0 (WY 1995-2023)
• April-July 2024: Updates to scenarios based on updates to Historical ESJWRM Version 3.0 (all use 55 years of hydrologic data: WY 1969-2023)
o PCBL Version 3.0
o PCBL-DR Version 3.0
o PCBL-PMA Version 3.0
o PCBL-CC Version 3.0
o PCBL-CC-DR Version 3.0
o PCBL-CC-PMA Version 3.0
o Use of Historical ESJWRM and PCBL related to interconnected surface water and groundwater storage
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 8 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
3 Historical Calibration Update
The Eastern San Joaquin Water Resources Model (ESJWRM or Model) was developed primarily to evaluate the current and recent historical groundwater conditions of the Eastern San Joaquin Groundwater Subbasin (ESJ Subbasin or Subbasin) and simulate various current and future condition scenarios as part of the Groundwater Sustainability Plan (GSP) preparation process under the Sustainable Groundwater Management Act (SGMA) (Woodard & Curran, 2018a). The fine geographic scale of the model provides the opportunity for individual Groundwater Sustainability Agencies (GSAs) to evaluate the effect of changing ESJ Subbasin conditions on smaller GSA areas. The Eastern San Joaquin Groundwater Authority (ESJGWA) was formed by a Joint Powers Agreement (JPA) and coordinates the SGMA activities for the Subbasin. The ESJGWA members include the 16 GSAs in the Subbasin.

As discussed in the section above, this report builds off of the earlier documents covering the Historical ESJWRM (Woodard & Curran, 2018a; Woodard & Curran, 2022a) and serves as an update the previous documentation and includes all updates made to the Historical ESJWRM Version 3.0 since the Historical ESJWRM Version 2.0 model report.

3.1 Purpose of Historical ESJWRM Version 3.0 Update
There were many factors driving the update of the historical ESJWRM in 2024. These factors included:
• Responding to Recommended Corrective Actions (RCAs) from the Subbasin’s 2020 GSP and 2022 Revised GSP
• Using the latest data and understanding for the preparation of the Periodic Evaluation and GSP o Extending hydrology through Water Year 2023
o Using Airborne Electromagnetic (AEM) data to refine model layering and stratigraphy o Using latest publicly released statewide land use data (DWR Statewide Crop Mapping for 2022)
o Updating distribution of rural residential urban demand within model o Understanding of demand reduction, projects & management actions, minimum thresholds, and interconnected surface water
• Updated tool to help understand and analyze conditions for the Subbasin or local agencies within the Subbasin

3.2 Current Conditions Baseline
The Current Conditions Baseline (CCBL) was previously a separate model scenario that was developed for the GSP but not maintained in the years and updates to the model since. Moving forward, the CCBL will represent a recent historical average and will be more consistent with the data reported in each Annual Report. Current conditions in Version 3.0 are represented as an average of the last five water years (2019- 2023) in Historical ESJWRM Version 3.0. This includes three (3) dry years and two (2) wet years.

3.3 Model Code and Data Updates Since 2022 Revised Groundwater Sustainability Plan Since the Historical ESJWRM Version 2.0 was finalized in 2022 (documented in Woodard & Curran, 2022a), there have been several updates to the model:

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 9 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024

1. Updates to monthly agricultural demand distribution for Historical ESJWRM resulting in Historical ESJWRM Version 2.2 (WY 1995-2020)

2. Extension of Data through Water Year 2021

3. Extension of Data through Water Year 2022

4. Extension of Data through Water Year 2023

5. Model Update and Recalibration in 2024 (resulting in Historical ESJWRM Version 3.0) In late 2022, the monthly agricultural demand distribution for Historical ESJWRM Version 2.0 was updated in select areas of the groundwater subbasin, causing slight changes to water budget numbers, but minimal differences to overall model calibration. Historical ESJWRM Version 2.2 was the result of edits to the minimum soil moisture for select crops, target soil moisture for several crops, and soil hydraulic conductivity by GSA. Additionally, several agricultural diversions were re-distributed to monthly values based on monthly demand averages. The changes to the model resulted in minor impacts to agricultural areas and focused on the monthly distribution of agricultural demand and supply in the model. The calibration of Historical ESJWRM Version 2.2 was consistent with Historical ESJWRM Version 2.0 as documented (Woodard & Curran, 2022a).

The next three updates were completed as part of the preparation of ESJ Subbasin GSP Annual Reports to the DWR. These updates included only an extension of model time series data (i.e., land use, surface water diversions, groundwater well pumping, and urban demand) and the model provided estimates of total surface water supplies, groundwater pumping, and change in groundwater storage for the water year covered by the model report. Updated data came from public sources for updated hydrology and from GSAs and Subbasin agencies for local water supplies. Below is a list of the agencies sent data requests for updates to model data:

Agricultural Water Purveyors
• Calaveras County Water District (CCWD)
• Central San Joaquin Water Conservation District (CSJWCD) • North San Joaquin Water Conservation District (NSJWCD) • Oakdale Irrigation District (OID)
• South San Joaquin Irrigation District (SSJID)
• Stockton East Water District (SEWD)
• Woodbridge Irrigation District (WID)
Municipal Water Purveyors
• California Water Service Company Stockton District (Cal Water) • City of Escalon
• City of Lodi
• City of Manteca
• City of Ripon
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 10 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
• City of Stockton
• Linden County Water District (LCWD)
• Lockeford Community Services District (LCSD)
• Stockton East Water District (SEWD)
Work on Historical ESJWRM Version 3.0 began in late 2023 and had the goals to update select datasets in the model, most notably the model layering by utilizing AEM survey data. The updates to Historical ESJWRM Version 3.0 were managed under the guidance of the ESJGWA’s Project Management Committee (PMC), The PMC was comprised of the following members, with representatives from most of the largest water districts in the Subbasin:
• Ashley Couch, Water Resources Manager of San Joaquin County • Justin Hopkins, General Manager of Stockton East Water District (SEWD) • Mitch Maidrand, Deputy Director of the Municipal Utilities Department of City of Stockton • Scot Moody, General Manager of Oakdale Irrigation District (OID) • Brandon Nakagawa, Water Resources Coordinator of South San Joaquin Irrigation District (SSJID) • Steve Schwabauer, General Manager of North San Joaquin Water Conservation District (NSJWCD) • Alternate: Andrew Watkins, SEWD Board Member
• Alternate: Hope Paulin, San Joaquin County Water Resources

3.3.1 IWFM Version
The model platform, IWFM-2015, has had several updates since Historical ESJWRM Version 2.0 was developed and the IWFM code has been updated to the latest release version (IWFM-2015 Version 1443) for Historical ESJWRM Version 3.0. New IWFM versions typically include error fixes and larger code changes that may impact the underlying calculations and therefore model results. Changes between model versions are documented on DWR’s IWFM website (https://water.ca.gov/Library/Modeling-and-Analysis/ModelingPlatforms/Integrated-Water-Flow-Model) and the latest IWFM technical memorandums are available online (Dogrul and Kadir, 2024a and 2024b). Since Historical ESJWRM Version 3.0 was finalized, an updated IWFM2024 Version 1594 was released. The impact of the model code changes will be evaluated in a future model update.

3.3.2 Hydrologic Period
The updated Historical ESJWRM Version 3.0 simulates water years 1995 through 2023 (October 1, 1994 through September 30, 2023). Most of the time series extensions took place during the model updates for the GSP Annual Reports, but are repeated in the sections below to fully document updates since Historical ESJWRM Version 2.0. These updates are listed in the sections below.

3.3.3 Precipitation
Consistent with previous ESJWRM reports, rainfall data for the model area is derived from the PRISM (Precipitation-Elevation Regressions on Independent Slopes Model) database used in the DWR’s CALSIMETAW (California Simulation of Evapotranspiration of Applied Water) model. The database contains ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 11 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
daily precipitation data from October 1, 1921 on a 4-kilometer grid throughout the model area (OSU, 2024).

ESJWRM has monthly rainfall data defined for every model element and adjacent foothill watershed in order to preserve the spatial distribution of the monthly rainfall. Each of the model elements was mapped to the nearest of 364 available PRISM reference nodes, uniformly distributed across the model domain. Historical ESJWRM Version 3.0 includes the mapped precipitation time series for water years 2016 through 2023.

3.3.4 Stream Inflow
Stream inflows to the model were extended using updated data from United States Geological Survey (USGS) stream gages and the United States Army Corps of Engineers (USACE) reservoir releases. Dry Creek, with data estimated using a regression after January 1998, was updated using recent monthly averages for similar water year types. At the time of the WY 2023 model report update, gage data for Mokelumne River and Stanislaus River were unavailable, so data for WY 2023 was updated using recent monthly averages for similar water year types. SSJID system outflows to Stanislaus River was extended using recent averages by aggregated water year types (wet, dry, and normal). A table of stream input data may be found in Table 1.

Table 1: Summary of ESJWRM Stream Inflow Data in Historical ESJWRM Version 3.0 Stream Stream
Node Source Gage Name Period of Record
Average
Annual
Streamflow
(acre-feet)
Cosumnes
River 1 USGS
USGS 11335000:

Cosumnes River at
Michigan Bar, CA
October 1907 to
present/ongoing 401,000
Dry Creek 140
USGS
Estimated in C2VSim by
correlation with USGS
11329500: Dry Creek near
Galt, CA
Not continuous
October 1926 to
December 1997
28,000 USGS
Estimated in C2VSim by
correlation with USGS
11335000: Cosumnes River
at Michigan Bar, CA
Used October 1987
to September 1995
and January 1998
to September 2015
n/a
Average of Historical Data
by Month and Water Year
Type
Used October 2015
to present/ongoing
Mokelumne
River 290 USGS
USGS 11323500:

Mokelumne River below
Camanche Dam, CA
October 1904 to
present/ongoing 550,000
Calaveras River 758
USGS
USGS 11308900: Calaveras
River below New Hogan
Dam near Valley Springs,
CA
February 1961 to
September 1990 162,000
USACE New Hogan Dam releases October 1990 to
present/ongoing
Stanislaus River 1033 USGS
USGS 11302000: Stanislaus
River below Goodwin Dam
near Knights Ferry, CA
February 1957 to
present/ongoing 577,000
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 12 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Stream Stream
Node Source Gage Name Period of Record
Average
Annual
Streamflow
(acre-feet)
Tuolumne River 1248 USGS
USGS 11289650: Tuolumne
River below Lagrange Dam
near Lagrange, CA
October 1970 to
present/ongoing 901,000
San Joaquin
River 1497 USGS
USGS 11303500: San
Joaquin River near
Vernalis, CA
October 1923 to
present/ongoing 3,145,000
SSJID System
Outflows to
Stanislaus River
1212 SSJID n/a n/a 24,000

3.3.5 Land Use and Cropping Patterns
Historical ESJWRM Version 3.0 update represents a larger shift in land use methodology than that described in previous updates. As a result, the land use data is described in full with text pulled from the Historical ESJWRM Version 1.1 model report (Woodard & Curran, 2018b).

For the model to calculate water supply requirements, every model element needs to have land use defined for every year of the simulation. Historical ESJWRM Version 3.0 uses the same land use categories as previous Historical ESJWRM versions and includes 23 irrigated crop categories and 3 general land use categories. All of the irrigated crop categories except for rice are simulated as non-ponded crops, meaning they are grown without standing water. Rice is simulated as both no decomposition (assumed 20% of total rice area) and flooded decomposition (assumed 80% of total rice area) to represent the current understanding of local growing practices. The general land use categories include urban landscape (e.g., residential areas, golf courses, and school fields), riparian vegetation (e.g., native vegetation located near surface water), and native vegetation. The irrigated crop categories were combined into 6 high-level groupings of crops with similar water use or irrigation practices. Table 2 lists the land use categories.

Table 2: Land Use Categories in Historical ESJWRM Version 3.0 Land Use Type Model Category Grouped Categories
Irrigated Crops
Almonds
Cherries
Citrus & Subtropical
Other Orchard
Pistachios
Walnuts
Fruit and Nut Trees
Vineyards Vineyards
Alfalfa
Pasture
Alfalfa and Irrigated
Pasture
Grain Grain
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 13 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Land Use Type Model Category Grouped Categories
Corn
Cotton
Dry Beans
Field Crops
Safflower
Sugar Beets
Field Crops
Cucurbits
Onion & Garlic
Potatoes
Tomato Fresh
Tomato Processing
Truck Crops
Truck Crops
Rice Rice
Other Land Use
Urban Landscape
Riparian Vegetation
Native Vegetation
Spatial land use data was used to specify land use types and crop acreages for each model element for each year. The major reference sources include DWR land use surveys, CropScape, DWR statewide crop mapping (previously referred to as LandIQ), and local information (including discussions with GSAs and referencing agricultural water management plans). Crop categories are not consistent across all the land use data sources, so individual mappings were developed to pair each crop type to a specific model land use category. The primary goal of the land use update for Historical ESJWRM Version 3.0 was to analyze and incorporate the recent statewide crop mapping provided by DWR. Previous updates had only briefly looked at and incorporated WY 2014 and WY 2016 data. The sources for land use data investigated are described below.
• Periodic land use surveys for each county by DWR. Surveys include over 70 different crop categories, as well as urban and native vegetation, for each parcel or field (DWR, 1993-2000). DWR land use surveys are regarded to have high accuracy due to extensive ground truthing. ESJWRM uses parts of county surveys from 1993 through 2000 to represent WY 1995 in the model, as explained further below.
• USDA’s remote sensing CropScape data is an annual dataset beginning in 2007 available for the entire country (USDA NASS, 2007-present). CropScape includes 256 land use categories that come from annual satellite imagery collected during the growing season on 30-meter by 30-meter pixels.

Based on reports on the CropScape website, the level of accuracy for this data is about 85-97% for crop-specific land cover categories. Although this level of accuracy is relatively high, the accuracy varies depending on many factors, including the time of the satellite image, growing season timing, cloud cover, type of crop, and maturity state of the crop. • Beginning in 2014, DWR retained Land IQ to develop a statewide assessment of agricultural land use in summer 2014. Land IQ used remote sensing methods to collect and process the data at the parcel scale, which was then ground truthed for a reported overall accuracy of 96.6% (DWR, 2014).

Land IQ did not include a native vegetation category, so any blank land was assumed to be native ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 14 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
vegetation. DWR contracted to produce the data more regularly and to date has published statewide land use data for 2014, 2016, 2018, 2019, 2020, 2021, and 2022.

With five consecutive years of DWR statewide surveys (2018-2022), several data sources used in the Historical ESJWRM Version 1.1 and Version 2.0 appeared to be inconsistent with the latest data from DWR in terms of cropping acreages and distribution of crops. For more consistency in cropping patterns and agricultural demand in the ESJWRM, the 2014 statewide crop mapping from DWR and the 2007-2015 CropScape data was removed from the model and replaced by interpolated acreages, as discussed in more detail below. Moving forward, the DWR statewide crop mapping will be processed and put in the model as updated data is available.

For ESJWRM, the land use surveys by county conducted by DWR were merged and assumed to represent water year 1995 in the model (Figure 1). Urban extent for this land dataset was reviewed and updated since county surveys had previously labeled roads as urban areas, but DWR statewide crop mapping did not include roads in the surveyed areas (so they were assumed to be native vegetation). The county land use surveys gave the impression of urban acreage decreasing during the model time period, which is inconsistent with local knowledge, so the urban acreage for 1995 was updated based on the extent of urban area in DWR statewide survey for 2022. The county surveys used to represent WY 1995 include:

1. San Joaquin County (1996)

2. Sacramento County (1993)

3. Amador County (1997)

4. Calaveras County (2000)

5. Stanislaus County (1996)
Along with the county surveys DWR uses for WY 1995, ESJWRM uses the DWR statewide crop mapping spatial data for 2016, 2018, 2019, 2020, 2021, and 2022. At the time of the Historical ESJWRM Version 3.0 development, 2023 data statewide crop mapping data was not yet available. Since there was no statewide crop mapping for 2017, 2016 land use is assumed to cover 2017 as well. Similarly, until 2023 statewide crop mapping is available, 2022 land use is assumed to represent 2023 as well.

To fill the gap between 1995 and 2016, all land use and crop categories that were originally from the USDA CropScape database were replaced and interpolated at the element level spatial resolution for each year.

Thus, the geographic distribution of interpolated land use and cropping patterns are honored.

Historical ESJWRM Version 2.2 update included revisions to the Subbasin’s two smallest GSAs, LCSD and LCWD, based on coordination with the GSAs. Due to the small size of these GSAs, model elements did not exactly align with GSA boundaries, so agricultural land use associated with the surrounding districts, NSJWCD for LCSD and SEWD for LCWD, was included in elements representing these two small urban communities. In discussions with the GSAs, it was agreed that the agricultural land use would be removed from model elements assigned to LCSD (15 elements) and LCWD (5 elements). In total, this edit impacted an average of 250 acres per year.

Figure 1 and Figure 2 show the spatial distribution of the land use categories in the Subbasin for 1995 and 2022. Figure 3 and Figure 4 show the pie charts of annual crop acreages in the Subbasin by grouped crop category for 1995 and 2022. Figure 5 shows the annual trends of all land use categories in the ESJ Subbasin and Figure 6 shows the annual trends of just grouped crop acreages in the Subbasin. Figure 5 shows how ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 15 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
urban acreage and crops as a whole increased in the Subbasin from 1995 to 2022, with native vegetation decreasing. Figure 6 makes the linear interpolation between 1995 and 2016 clear and shows how there are small changes even among the statewide crop mapping datasets from year to year, which are expected to continue as new datasets are added to the model.

Overall, land use trends from 1995 through 2023 show a 4.7% increase in total and irrigated agricultural acreage, with about 380,000 irrigated acres in ESJ Subbasin at the beginning of simulation and about 398,000 acres with agricultural production by 2023. . As shown in Figure 3 and Figure 4, fruit and nut trees show the largest growth, both in terms of acreage and in terms of the proportion of the total crops in the Subbasin.

Historical ESJWRM Version 3.0 changes to the land use methodology overall included changes to the total agricultural land as a result of removing CropScape data from 2007-2015 and reducing urban acreage in the 1995 dataset caused by the transfer of roads from urban to native vegetation in order to be more consistent with the methodology of the recent DWR statewide crop mapping. As shown in Figure 7, the urban acreage is reduced by 23,000 acres in 1995 and all of it becomes native vegetation, which increases by 23,000 acres in 1995. The removal of CropScape data leads to impacts to the agricultural area, native vegetation, and urban area, and changes in CropScape years leads to differences in the linear interpolation years between 1995 and 2007.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 16 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 1: 1995 Land Use in Historical ESJWRM Version 3.0 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 17 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 2: 2022 Land Use in Historical ESJWRM Version 3.0 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 18 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 3: 1995 Grouped Crop Acreage for ESJ Subbasin in Historical ESJWRM Version 3.0 Figure 4: 2022 Grouped Crop Acreage for ESJ Subbasin in Historical ESJWRM Version 3.0 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 19 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 5: Annual Land Use for ESJ Subbasin in Historical ESJWRM Version 3.0 ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 20 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 6: Annual Grouped Crop Acreage for ESJ Subbasin in Historical ESJWRM Version

3.0 Figure 7: Difference between Historical ESJWRM Version 3.0 and Historical ESJWRM Version 2.2 Land Use Acreages by Broad Category
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 21 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024

3.3.6 Model Layering
The Historical ESJWRM Version 3.0 has undergone significant refinements to better reflect subsurface conditions and improve the accuracy of groundwater dynamics. Historical ESJWRM Version 2.2 and earlier was based on the C2VSimFG Version 1.0 layering; the layering was fully updated for the Historical ESJWRM Version 3.0 and the stratigraphy now includes a newly defined shallow alluvium layer, updated Corcoran Clay boundaries, and refined model layers informed by the recent airborne electromagnetic (AEM) surveys.

DWR recently conducted airborne electromagnetic (AEM) surveys in high and medium-priority groundwater basins across California. The purpose of the AEM surveys was to provide technical assistance to water managers implementing GSPs under SGMA by providing data on subsurface hydrogeologic characteristics for aquifer systems underlying the surveyed groundwater basins. AEM surveys provide high resolution, geologically-based data to support both validation and refinement of the existing understanding of the Subbasin’s aquifer system. AEM includes detailed resistivity and texture datasets and information related to the coarseness of sediments (sands versus clays), the degree of saturation of rock (saturated or not), and the water quality of saturated rock (saline or not). AEM surveys measure the electrical resistivity of subsurface materials, allowing geophysicists to interpret subsurface lithology, to identify and map structural features such as faults, and to assess water quality including the presence and extent of saltwater intrusion.

This dataset is invaluable for refining layers by providing a new large-scale, vertically and horizontally continuous texture dataset, which is particularly useful in areas where existing well logs may not provide a full picture of subsurface conditions.

The ESJ Subbasin was surveyed in April 2022 (Figure 8). The AEM data were processed and used to generate three resistivity inversion models; a smooth, sharp, and a few-layer model. The AEM data were then processed using compiled lithologic well logs that were converted to coarse and fine-material classifications. These binary classifications were correlated to the resistivity values to produce a percent coarse-fraction texture model for each flight line. This texture model, along with existing surficial geologic maps, was used to update the ESJWRM layers.

Figure 8: 2022 AEM Survey Lines Above ESJ Subbasin
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 22 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
To update the model layers, cross sections for each flight line in the ESJWRM extent were developed, showing the AEM coarse-faction data, supplemental well logs, and existing model layers (Figure 9). Picks were identified for where model layers should exist based on contacts mapped in the texture dataset. The location of where layers were pinching out at the surface were identified by formation outcrop locations pulled from surface geology maps. In areas with data gaps in the AEM resistivity survey, such as urban areas, areas with confined livestock, and vineyards (Figure 8), contacts identified in supplemental well logs were relied upon. These picks were then interpolated to generate an updated model surface using the ESRI ArcGIS platform. The new model layers were printed on the cross section to compare how the resulting surfaces matched the texture dataset and were iteratively refined as needed.

ESJWRM model layers were updated using a combination of AEM resistivity and texture data, lithologic well logs, and existing geologic maps, resulting in a more accurate representation of the subsurface conditions within the ESJWRM extent.

Figure 9: Example of 3-D Representation of AEM Data with Well Logs

3.3.6.1 Defining Shallow Alluvium Layer
The purpose of defining a new shallow layer in ESJWRM was to create a near surface layer that better represents shallow alluvium. The ideal layer was determined to have the following attributes:
• Captures the coarse deposits that interact with the surface • Has useful thickness and depth in model area and along streams • Include formations of similar, generally coarse, alluvial rock types • Is regionally consistent
Geologic formations within the ESJWRM extent were compared based on their depositional environment, degree of consolidation, and age. Generally, younger, unconsolidated or loosely consolidated coarser ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 23 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
deposits were identified as suitable formations for inclusion in the shallow alluvium layer. The following formations were considered in this evaluation:
• Modesto and Riverbank Formations
• Turlock Lake
• Tulare
• Unnamed very young fan deposits
The Laguna Formation, which underlies the formations listed above, is considered the most consolidated and the oldest of all alluvial deposits in the model extent. It was determined to be too deep to be useful for evaluating groundwater dynamics in the shallow parts of the alluvium. Therefore, the new shallow Layer 1 was defined as the depth to the top of the Laguna Formation.

Portions of the new Layer 1 were further adjusted to accommodate modeling constraints. Some portions of the new Layer 1 were extremely thin (<10 feet), which could cause computational problems. A minimum thickness of 20 feet was applied to all areas where Layer 1 existed to ensure the model could converge.

Additionally, streams must be able to recharge water into the top-most layer, so the thickness of Layer 1 was adjusted at stream nodes to a minimum thickness of 20 feet plus the largest stream depth. This adjustment is consistent with typical alluvial sediments deposition patterns.

3.3.6.2 Updating Foothill Layering
Historical ESJWRM Version 2.2 and earlier stratigraphy based on C2VSimFG’s model layering had well refined layers in the western portion of the model extent, but layers did not follow the dips of the geologic formations as they approached the Sierra Nevada foothills towards the east. The purpose of refining the layering in Historical ESJWRM Version 3.0 was to generate more realistic, geologically representative layers that better reflect subsurface conditions.

3.3.6.3 Updating Corcoran Clay Extent
The existing Corcoran Clay layer in Historical ESJWRM Version 2.2 and earlier was based on the Central Valley Hydrologic Model (CVHM) spatial database. The extent, depth, and thickness of the Corcoran Clay were updated using data re-downloaded from the USGS (Faunt, 2012). Contours of the Corcoran Clay’s depth and thickness were interpolated to create continuous top and bottom surfaces, which were then mapped to the ESJWRM groundwater nodes.

Most of the previous ESJWRM Corcoran Clay extent aligned with the updated USGS dataset, except for the northern extent, which previously stopped halfway between Ripon and Manteca. The new northern boundary now extends just north of Lathrop and Manteca. While the thickness of the Corcoran Clay remained similar in areas along the Stanislaus River, it changed by as much as 100 feet in other areas compared to the previous layers.

3.3.6.4 Final Model Layers
The final model layers are described below, in order from top to bottom. • Layer 1: This layer represents the shallowest alluvium in the model extent, consisting of coarse unconsolidated to semi-consolidated deposits that interact with the ground surface and streams.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 24 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
The top of the layer is defined by the ground surface elevation from the USGS 10-meter resolution DEM. The bottom of the layer is generally defined by the top of the Laguna Formation. • Layer 2: This layer represents the remaining top unconfined portion of the aquifer, consisting of older alluvium deposits such as those from the Laguna Formation. The top is defined as the bottom of Layer 1. In the AEM texture cross sections, the base of Layer 2 was identified by the base of a distinct coarse bed representing the unconsolidated to semi-consolidated alluvial sands, gravels and silts of the Laguna Formation. Where the Corcoran Clay exists, the base of Layer 2 is defined as the top of the Corcoran Clay.
• Aquitard 2: The Corcoran Clay separates Layers 2 and 3 in the southwest corner of the model. The extent, thickness, and depth of the Corcoran Clay originated from the CVHM spatial database published by the USGS.
• Layer 3: This layer represents the primary pumping layer in ESJWRM. It is located beneath the confining layer where the Corcoran Clay exists and below Layer 2 in the rest of the model extent. In the AEM texture cross sections, the top of this layer was often identified by a distinct contact between coarse and finer sediments, aligning with the finer-grained deposits (black sands interbedded with clays) of the upper Mehrten Formation. The bottom generally aligns with the base of the Mehrten Formation.
• Layer 4: This layer represents the confined portion of the aquifers that extends to the base of freshwater. The original development of the bottom of Layer 4 included data provided by DWR and Williamson et al. 1989.
• Layer 5: This layer consists of saline water, ranging from the base of freshwater to the base of continental deposits, and is currently a non-production zone. The original development of the bottom of Layer 5 included Page 1974’s “Base and Thickness of the Post-Eocene Continental Deposits in the Sacramento Valley” and the thickness of the aquifer developed by Williamson et al. 1989.

3.3.6.5 Comparison of Updated Layers in Previous ESJWRM Versions Table 3 includes a useful comparison of the mapping of the old layering used in Historical ESJWRM Version

2.2 and earlier and the updated layering used in Historical ESJWRM Version 3.0 moving forward. Though layer thicknesses sometimes changed dramatically, especially in the Sierra Nevada foothill areas, the understanding of the layering remains consistent.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 25 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Table 3: Difference between Historical ESJWRM Version 3.0 and Historical ESJWRM Version 2.2 and Earlier Layering
Layering in
Historical
ESJWRM
Version 3.0
Layering in
Historical
ESJWRM
Version 2.2
and Earlier
Understanding of Layer
Extent
Understanding
of Layer
Confinement
Layer 1 Layer 1 Shallowest alluvium Unconfined
Layer 2 Older alluvium Unconfined
Corcoran Clay
Aquitard
(where exists)
Corcoran Clay
Aquitard
(where exists)
Confining unit Confining unit
Layer 3 Layer 2 Primary pumping layer Confined
Layer 4 Layer 3 Pumping layer, extends to
base of fresh water Confined
Layer 5 Layer 4
Saline water, no pumping,
extends to base of
continental deposits
Confined
The figures below (Figure 10, Figure 11, and Figure 12) show the AEM data along survey lines in the model domain with coloring according to the coarse fraction (darker=finer and coarser=lighter). ESJWRM layering is shown in red lines with Historical ESJWRM Version 2.2 and earlier on the top figure and the updated layers in Historical ESJWRM Version 3.0 in the bottom figure.

The model stratigraphy refinements in Historical ESJWRM Version 3.0 have many benefits to the model and the understanding of the aquifer system underlying the Subbasin. These benefits include:
• River reaches with hydraulic connection to the shallow alluvium which have stream-groundwater interaction are more readily identified in the model
• Improved ability to model recharge projects and quantify benefits • Improved representation of Corcoran Clay
• Representation of hydrogeology in the Sierra Nevada foothills is more realistic and allows for direct recharge of deeper layers
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 26 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 10: North-South Example of Historical ESJWRM Version 3.0 (bottom) and Historical ESJWRM Version 2.2 and Earlier (top) Layering with AEM Coarse Fraction
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 27 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 11: Northern East-West Example of Historical ESJWRM Version 3.0 (bottom) and Historical ESJWRM Version 2.2 and Earlier (top) Layering with AEM Coarse Fraction
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 28 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Figure 12: Southern East-West Example of Historical ESJWRM Version 3.0 (bottom) and Historical ESJWRM Version 2.2 and Earlier (top) Layering with AEM Coarse Fraction
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 29 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024

3.3.7 Boundary Conditions
The boundary conditions in the model remain the same as ESJWRM Version 2.2, with some edits due to the inclusion of the additional model layer (see Section 3.2.6), Boundary conditions in ESJWRM consist of eastern flows from the Sierra Nevada Mountains simulated in the model as small watersheds, Camanche Reservoir seepage estimated using a constrained general head boundary condition, Woodward Reservoir, Farmington Dam, and Modesto Reservoir seepage represented as stream diversions, flows from outside of the model area represented with general head boundary conditions, and groundwater levels at or near zero near the edges of the Sacramento-San Joaquin Delta are represented using specified head boundary conditions. Data was extended through water year 2023 using a monthly average by water year type. Layer assignments increased by one to account for the new model layering and new lines were added for boundary conditions related to the new Layer 1. Small watersheds all previously drained their baseflow into Layer 1, but in Historical ESJWRM Version 3.0 were updated to drain into the top model layer (since Layer 1 isn’t continuous across the model).

3.3.8 Urban Demand
Urban demand, comprised of annual population and monthly per capita water use (PCWU), is specified for incorporated urban areas or communities and estimated for rural urban demand. No changes were made to the urban demand for incorporated areas from Historical ESJWRM Version 2.2, which are still based on Department of Finance population data and urban demand calculated as surface water deliveries plus groundwater pumping deliveries.

The rural population, or people not in urban centers, was previously estimated in Historical ESJWRM Version

1.1 and Version 2.0 by calculating an estimate of the rural population per acre in San Joaquin County and applying that population estimate to the unincorporated acreage of the model. This method lumped all rural residential population into one large group that was then spatially assigned by the model based on urban acreage. Since the group area covered all areas in Cosumnes, ESJ, and Modesto Subbasins that were not covered by urban centers, the area of distribution of the urban demand was most likely not realistic.

In Historical ESJWRM Version 3.0, the rural residential population was updated to rely on Census Tract, which are much smaller areas that can more accurately pinpoint where urban demand is occurring in the model (demand within the Census Tract will still be assigned based on urban acreage). The data used was a downloaded Census Tract shapefile and the annual population per tract (American Community Survey Total Population or B01003 for 2010 through 2022 at time of model update), both from the United States Census Bureau. Population data was extrapolated backwards to 1995 and forwards to 2023 using reasonable trends determined from the 2010 through 2022 population data or from nearby urban cities. City populations were removed from Census Tracts, leaving only rural residential population remaining in each Census Tract. This population is combined with a monthly per capita water use determined by averaging ESJ Subbasin urban areas’ per capita water uses.

The change in rural residential urban demand increased the rural population and increased the total urban demand in the Historical ESJWRM Version 3.0 by almost 13 TAFY (demand is met entirely by groundwater pumping).

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 30 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024

3.3.9 Surface Water Diversions
Surface water diversions were not largely changed from Historical ESJWRM Version 2.0. Two additional diversions were added:
• NSJWCD south system recharge
• Farmington reservoir seepage
Three additional diversions were edited:
• Separated NSJWCD south system agricultural use from recharge (due to new diversion above) • Losses from New Hogan delivery system associated with SEWD operations • Losses from New Melones delivery system associated with SEWD operations GSAs provide updated surface water diversion data on an annual basis during GSP Annual Report model updates. If GSAs do not provide updated numbers, recent historical averages by water year type are used instead. A summary of diversions simulated in the model is provided in Table 4, 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).

Historical ESJWRM Version 3.0 includes 66 diversions, 63 of which are listed in Table 4 and 3 diversions that are placeholders that are not currently being used in the model. The Projected Conditions Baseline Version

3.0 averages are also included in Table 4 and are discussed in Section 4.1.3.

ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 31 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
Table 4: Summary of ESJWRM Surface Water Deliveries in Historical ESJWRM Version 3.0 and PCBL Version 3.0 ID Description Diversion
Location Delivery Area Primary Use
Fraction
Historical
ESJWRM
Version 3.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 3.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
1 Mokelumne River to
North San Joaquin
WCD North System
for Ag
Mokelumne
River
North San
Joaquin WCD
North System
Ag 50% 0% 50% 370 0 NSJWCD
2 Mokelumne River to
North San Joaquin
WCD South System
for Ag
Mokelumne
River
North San
Joaquin WCD
South System
Ag 0% 0% 100% 410 2,000 NSJWCD
3 Mokelumne River to
North San Joaquin
WCD for CALFED GW
Recharge Project
Mokelumne
River

CALFED GW
Recharge Project Recharge 100% 0% 0% 250 800 NSJWCD
4 Mokelumne River to
North San Joaquin
WCD For Tracy Lake
Recharge Project
Mokelumne
River
Tracy Lake
Recharge Project Recharge 50% 0% 50% 270 2,000 NSJWCD
5 Mokelumne River to
City of Lodi (by
agreement with
Woodbridge ID) for
M&I
Mokelumne
River City of Lodi Urban 0% 0% 100% 5,400 5,000 Lodi
6 Mokelumne River to
City of Lodi (by
agreement with
NSJWCD) for M&I
Mokelumne
River City of Lodi Urban 0% 0% 100% 370 0 Lodi
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 32 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
ID Description Diversion
Location Delivery Area Primary Use
Fraction
Historical
ESJWRM
Version 3.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 3.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
7 Mokelumne River to
City of Lodi (banked
from agreement with
WID) for M&I
Mokelumne
River City of Lodi Urban 0% 0% 100% 550 0 Lodi
8 Mokelumne River to
Woodbridge ID for
Ag
Mokelumne
River
Woodbridge
Irrigation District Ag 30% 2% 68% 57,800 44,000 WID
9 Mokelumne River
Export to Contra
Costa WD (by
agreement with
Woodbridge ID)
Mokelumne
River
Export out of
model Urban 0% 0% 100% 2,000 0 WID
10 Mokelumne River to
City of Stockton for
Delta Water Supply
Project (by
agreement with
Woodbridge ID) for
M&I
Mokelumne
River City of Stockton Urban 0% 0% 100% 7,500 10,000 City of Stockton
11 San Joaquin River at
Empire Tract to City
of Stockton for Delta
Water Supply Project
for M&I
San Joaquin
River City of Stockton Urban 0% 0% 100% 9,500 21,000 City of Stockton
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 33 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
ID Description Diversion
Location Delivery Area Primary Use
Fraction
Historical
ESJWRM
Version 3.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 3.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
12 Calaveras River to
Bellota Pipeline to
Stockton East WD
WTP for M&I
Calaveras
River
Export out of
model (imported
in Diversions 14,
15, and 16)
Urban 0% 0% 100% 13,700 13,000 SEWD
13 Stanislaus River at
Goodwin Dam to
Farmington Flood
Control Basin to
Lower Farmington
Canal to Peters
Pipeline to Stockton
East WD WTP for
M&I
Import
(outside of

ESJWRM)
Export out of
model (imported
in Diversions 14,
15, and 16)
Urban 0% 0% 100% 28,000 49,000 SEWD
14 Stockton East WD
WTP to City of
Stockton for M&I
Import
(exported in
Diversions 12
and 13)
City of Stockton Urban 0% 0% 100% 17,900 5,000 UWMP
15 Stockton East WD
WTP to Cal Water for
M&I
Import
(exported in
Diversions 12
and 13)
Cal Water Urban 0% 0% 100% 21,700 19,000 UWMP
16 Stockton East WD
WTP to San Joaquin
County in Stockton
for M&I
Import
(exported in
Diversions 12
and 13)
San Joaquin
County in
Stockton
Urban 0% 0% 100% 1,400 2,000 UWMP
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 34 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
ID Description Diversion
Location Delivery Area Primary Use
Fraction
Historical
ESJWRM
Version 3.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 3.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
17 Calaveras River to
Calaveras County WD
for Ag
Import
(outside of

ESJWRM)
Calaveras County
WD Ag 9% 1% 90% 1,100 1,000 CCWD
18 Calaveras River to
Jenny Lind for M&I
Import
(outside of

ESJWRM)
Jenny Lind Urban 0% 0% 43% 1,800 2,000 CCWD
19 Calaveras River to
Stockton East WD for
Ag
Calaveras
River
Stockton East
Water District Ag 0% 0% 100% 23,600 21,000 SEWD
20 Calaveras River to
Stockton East WD
Losses
Calaveras
River
Stockton East
Water District,
including canals
Recharge 89% 11% 0% 17,600 17,000 SEWD
21 Calaveras River to
Farmington
Groundwater
Recharge Program
Calaveras
River
Farmington
Groundwater
Recharge
Program
Recharge 100% 0% 0% 1,900 5,000 SEWD
22 San Joaquin River to
North Delta for Ag
San Joaquin
River
North Delta
Subregion Ag 5% 1% 94% 139,000 126,000 Estimated by model 23 San Joaquin River to
South Delta for Ag
San Joaquin
River
South Delta
Subregion Ag 5% 1% 94% 27,400 19,000 Estimated by model 24 Stanislaus River at
Goodwin Dam to
Farmington Flood
Control Basin to
Lower Farmington
Canal to Stockton
East WD for Ag
Import
(outside of

ESJWRM)
Stockton East
Water District Ag 0% 0% 100% 4,500 7,000 SEWD
ATTACHMENT 2
Eastern San Joaquin Groundwater Authority 35 Woodard & Curran, Inc.

ESJWRM Version 3.0 October 2024
ID Description Diversion
Location Delivery Area Primary Use
Fraction
Historical
ESJWRM
Version 3.0
Average
Annual
Diversion***
(acre-feet)
PCBL
Version 3.0
Average
Annual
Diversion***
(acre-feet)
Data
Source
RL* NL** Delivery
25 Stanislaus River to
Stockton East WD
Losses
Import
(outside of

ESJWRM)
Stockton East
Water District,
including canals
Recharge 88% 12% 0% 3,800 7,000 SEWD
26 Stanislaus River at
Goodwin Dam to
Farmington Flood
Control Basin via
Little Johns Creek and
Lower Farmington
Canal to Central San
Joaquin WCD for Ag
Import
(outside of

ESJWRM)
Central San
Joaquin WCD Ag 15% 2% 83% 30,600 24,000 SEWD
27 Stanislaus River to
Farmington
Groundwater
Recharge Program
Import
(outside of

ESJWRM)
Farmington
Groundwater
Recharge
Program
Recharge 100% 0% 0% 3,600 5,000 SEWD
28 Stanislaus River at
Goodwin Dam to
Oakdale ID North for
Ag
Import
(outside of

ESJWRM)
Export out of
model (imported
in Diversions 52,
55, and 57)
Ag 0% 0% 0% 98,600 88,000 OID
29 Stanislaus River at
Goodwin Dam to
Oakdale ID South for
Ag [Modesto
Subbasin]
Import
(outside of