Sutter Creek City Council
March 17, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
• The water balance shall reflect true site conditions, and not include operational decisions that would cause a violation of the WDRs, applicable enforcement Order, or any applicable regulation. For example, the water balance cannot include assumptions such as the use of an unpermitted discharge to surface water, irrigation when LAAs are saturated, or discharge at a flow rate that would cause violations of applicable effluent limits. If the current facility cannot accommodate current or projected 5 year flows the volume of that deficit shall be calculated as required by Item 3 of the 14 August 2024 Water Code Section 13267 Order. In order to properly examine the water balance calculations, it is necessary that the spreadsheets containing the data and formulas are submitted along with the narrative portion of the report. All spreadsheets used to construct the tables and surmise conclusions shall be submitted.

EXISTING FACILITIES
This section provides an overview of the WWTF pond system and LAA facilities.

WWTF Pond System
The WWTF is a pond-based treatment facility owned by the City and operated under contract by WaterStone Services, LLC. The WWTF is located south of the City, near the intersection of Marlette Road and Dave Brubeck Road. A map of the WWTF and connected facilities is shown on Figure 1. A flow schematic of the WWTF system is shown on Figure 2.

The WWTF treats wastewater generated from the City in five lined and aerated treatment ponds (Ponds 1 through 5). These ponds provide secondary wastewater treatment through aeration and settling. Pond 5 was historically operated as a percolation pond and is described as such in the current WDRs. However, with the lining and aeration improvements made since the WDRs were adopted, Pond 5 currently functions as a treatment pond. Ponds 6 and 7 are currently used for disposal through percolation and evaporation during periods when the effluent cannot be used for irrigation purposes. 399
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LEGEND
City of Ione
Updated Water Balance Project No.: 988-50-24-10

CITY OF IONE

SANITARY SEWER
USERS

WWTF EFFLUENT

WWTF INFLUENT
Figure 2. WWTF System Schematic

AWA FILTER

BACKWASH

CITY OF IONE
WWTF
(PONDS 1-5)

COWRF FILTER

BACKWASH

CITY FIELD

5.6 ACRES

TOWN FIELD
57 ACRES

PERCOLATION
PONDS 6 & 7

CROP UPTAKE

CROP UPTAKE

PERCOLATION

EVAPORATION

EVAPORATION

EVAPORATION

IRRIGATION

PUMP STATION
& FLOW METER

FIELD RUNOFF
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Detailed dimensions of each pond are presented in Table 1. Figure 3 provides a more detailed layout of the City’s pond system, interconnection piping and groundwater monitoring piezometers described further below.

Table 1. WWTF Pond Dimensions
Pond(a) Depth,
(b)
feet
Water Surface
Area,
(b) acres
Volume,
(b)
million gallons
(MG)
Volume,
(b)
acre-feet
Pond Bottom
Elevation,
feet mean sea
level (msl)
1 8.0 1.5 3.2 9.8 265.0
2 8.0 1.2 2.2 6.8 265.0
3 7.0 1.0 1.8 5.5 266.0
4 8.0 2.0 3.8 11.7 265.0
5 10.0 4.7 13.6 41.8 263.0
6 7.3 3.9 8.2 25.2 266.7
7 5.3 5.3 8.4 25.8 265.7
Source: 2017/2018 Pond 1-5 As-Built Survey
(a) Information for Ponds 1 - 5 is from the 2017/2018 Pond 1-5 As-Built Survey. Information for Ponds 6 and 7 is from the 2020 Capacity Expansion Completion Report.
(b) Depth, surface area and volume are shown at two feet of freeboard.

Quarterly groundwater monitoring is conducted at serval monitoring wells associated with the WWTF site. Piezometers 1, 2 and 3 (P1, P2 and P3) are specifically used to measure the groundwater elevations surrounding unlined Ponds 6 and 7. As shown on Figure 3, P1 lies on the east side of Pond 7, P3 lies in the northwest corner of Pond 7, and P2 lies northeast of Pond 6 adjacent to Sutter Creek. In this location, groundwater elevations at P2 are also likely influenced by creek water levels. 402
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
The influence of the WWTF ponds on the groundwater elevations at the WWTF site has changed significantly since the lining of Ponds 1 through 5 in 2019. Therefore, an assessment of depth to groundwater beneath the ponds should be based on data collected since 2019. A review of post 2019 quarterly groundwater monitoring data indicates that the highest groundwater elevations at P1, P2 and P3 occurred in the first quarter of 2023 (P2) and first quarter of 2024 (P1 and P3). The lowest groundwater elevations occurred in the third quarter of 2021 (for all 3). The groundwater elevations and corresponding depths below the invert of Ponds 6 and 7 for these periods are shown in Table 2 and Table 3. Groundwater elevation gradient maps from these monitoring periods are also included in Attachment A, taken from the respective quarterly monitoring reports prepared by others for the City.

Table 2. Pond 6 Depth to Groundwater
Measurement
Period Season
P2 Groundwater Elevation,
feet msl
Groundwater Depth
Below Pond 6, feet(a)
Q3 2021 Dry 257.30 9.4
Q1 2023
Wet
264.10 2.6
Q1 2024 262.64 4.1
(a) Groundwater depths below the invert of Pond 6 at 266.7 feet msl based on the respective P2 groundwater elevations.

Table 3. Pond 7 Depth to Groundwater
Measurement
Period Season
Groundwater Elevation, feet msl Average Groundwater
Depth Below Pond 7, feet(a) P1 P3 Average
Q3 2021 Dry 256.80 251.60 254.20 11.5
Q1 2023
Wet
264.11 259.11 261.61 4.1
Q1 2024 264.61 260.44 261.03 4.7
(a) Groundwater depths below the invert of Pond 7 at 265.7 feet msl based on the respective averages of P1 and P3 groundwater elevations.

Land Application Areas
During the summer irrigation season, treated WWTF effluent is distributed via the secondary effluent pump station to two LAAs: the Town Field and City Field. Pertinent details regarding these two LAAs are as follows:
• Both LAAs are used to grow fodder crops (i.e. crops not intended for human consumption). • As shown on Figure 1, the City Field is a 5.6-acre area located within the WWTF site.

Currently, alfalfa is grown on the City field.
• The Town Field is a 57-acre irrigation site owned by Jackson Rancheria and is located directly east of the WWTF (see Figure 1).
• Since the City began irrigating the site with recycled water, alfalfa has been grown on this the Town Field.
• Both LAAs are irrigated by hand-move spray irrigation systems and are managed by an agricultural worker employed by Jackson Rancheria.
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
• Runoff is collected from the Town Field year-round and returned to the WWTF via the City’s collection system.
• Runoff from the City Field is collected during the irrigation season. During the winter months, runoff is allowed to pond within the property until it evaporates or percolates.

A certification letter from Jackson Rancheria specific to the Town Field recycled water operations is provided in Attachment B.

Facility Changes Impacting Treatment Capacity Defined in the ROWD The City has made significant changes to the WWTF since the development of the 2012 ROWD, as discussed above. These changes have impacted both the treatment and disposal capacity values that were stated in the ROWD, and that are documented in the WDRs2.

With respect to treatment capacity, the WDRs state that the City reported that the influent ADWF capacity of the WWTF is 0.55 mgd. A disconnect between the stated capacity and the improvements made to the pond treatment system is found upon review of the June 2009 Wastewater Master Plan (Lee & Ro, Inc. and PMC, 2009), the March 2010 ROWD (Lee & Ro, Inc., 2010) and the November 2012 Supplement to the Revised ROWD (GHD Inc., 2012b). Specifically, the capacity statements made in the 2010 ROWD lean heavily on the 2009 Wastewater Master Plan values to define capacity with little to no assessment of the benefits provided by the City’s projects that provided solids removal, pond lining, and increased aeration.

Moreover, the 2009 Wastewater Master Plan does not characterize or assess the low load flows (i.e. backwash from the Castle Oaks Water Reclamation Facility (COWRF) and filter backwash from the Ione Water Treatment Plant (WTP)) that contribute to the ADWF entering the WWTF but have virtually no impact on treatment capacity.

Table 4 provides a summary of the aeration improvements made to the pond system since 2009. As shown, the City has significantly increased the aeration provided in the treatment ponds. This increase provides for added capacity through increased oxygen availability and improved mixing. More importantly, by lining and adding aeration to Pond 5, this facility no longer operates as a percolation/disposal pond as described in the WDRs. Indeed, Pond 5 is now better characterized as a treatment pond.
2 As previously noted, and as documented in the 2014 WDR Amendment, the City has also made operational changes that have increased the available disposal capacity of the percolation ponds. However, because these water balances may not consider the percolation ponds as a vehicle for disposal, additional discussion regarding these changes is not included in this report.
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Table 4. WWTF Pond System Aeration Improvements
Facility
Original Aeration
Capacity
Upgraded Aeration
Capacity
Upgraded Aerator
Type
Pond 1 1 aerator @
15 horsepower (HP)
[email protected] HP
1@ 15 HP
Floating Brush
High-Speed Floating
Pond 2 1@ 7.5 HP 1@ 7.5 HP
1@ 15 HP
Floating Brush
High-Speed Floating
Pond 3 1@ 7.5 HP 1@ 7.5 HP
1@ 15 HP
Floating Brush
High-Speed Floating
Pond 4 1@ 7.5 HP 1@ 7.5 HP Floating Brush
Pond 5 None 2@15) HP High-Speed
A preliminary modeling analysis of the treatment pond system was developed to define the capacity of the ponds at current flow rates and at the projected 2030 flow rates, as defined in this TM. In addition, a model was developed to define the overall treatment capacity. For this analysis, the following assumptions were applied:
• Biochemical Oxygen Demand (BOD) removal in Ponds 1 through 4 is a first-order mechanism, where the first-order removal-rate constant “k” at 20 degrees Celsius (°C) is assumed to be 0.276 per day (U.S. Environmental Protection Agency, 2011). • For Pond 5, the first order rate coefficient was defined based on the loading rate to the pond. Values ranged from 0.083 to 0.129 per day.
• The reaction rate coefficients were adjusted to reflect a treated water temperature of

10.9°C, which is based on the lowest monthly average measured influent temperature of Pond 5 in December and January. Assuming that the influent temperature of Pond 5 is the treatment temperature for all upstream ponds is a conservative assumption. • The available volume of Pond 5 was adjusted down from the total capacity of 13.7 million gallons (MG) to 10.1 MG (or 31 acre-feet) based on average December through January operating levels (see Table 33 later in this TM).

The results of this analysis are shown in Table 5. As shown, the existing treatment system potentially has a theoretical ADWF capacity to process flows up to 0.72 mgd. 406
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Table 5. WWTF Treatment Pond Modeling Analysis Results
Parameter Units
Current (2024)
Flows
Year 2030
Flows
Estimated
Design
Flows
Base Flow mgd 0.41(a) 0.51(b) 0.58
ADWF(c) mgd 0.55 0.65 0.72
Maximum Month Influent Flow mgd 1.09 1.34 1.53
Maximum Month Influent BOD Load pounds per day 1,450 1,800 2,060 Pond 4 Effluent BOD mg/L 32 41 48
Pond 5 Effluent BOD mg/L 20 24 30
(a) See Current (2024) Influent Flows section presented later in this TM. (b) See Projected 2030 Influent Flows section presented later in this TM. (c) Difference between Base Flow and ADWF values are the non-load inputs from sewer system inflow and infiltration, COWRF filter backwash, and AWA WTP filter backwash.

The City is currently working to update and calibrate the model of the treatment system. A final assessment of the current WWTF treatment capacity, including Pond 5, will be presented in a technical report prepared by a California Licensed Civil Engineer.

It is also noted that the effluent limitations described in the WDRs are specifically applied to effluent discharged to the percolation ponds. Since Pond 5 is lined it no longer is a percolation pond, these limits should apply only to discharges to Pond 6 and Pond 7. To remedy this, the City proposes a modification to the MRP3to change the effluent monitoring location.
3 The City will need to develop new water storage and/or effluent management strategies to ensure compliance with the CDO. Once the new strategies are identified, the City will be in position to prepare and submit a new ROWD so support development of a new permit that incorporates changes to the treatment system. 407
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
A summary of the proposed changes to the MRP is provided in the table below.

The City of Ione shall collect un-disinfected effluent samples immediately downstream of Pond 4 5 before the effluent is discharged into the percolation ponds. At a minimum, effluent monitoring shall include the following:

Constituent Units Sample Type
Sample
Frequency
Reporting
Frequency
ARSA secondary effluent flows to
the percolation ponds gpd Meter Observation Daily Monthly Total effluent flows to the
percolation ponds 1, 2 gpd Calculated Daily Monthly
BOD5 mg/L Grab Monthly Monthly
Total dissolved solids mg/L Grab Monthly Monthly
Electrical conductivity µmhos/cm Grab Monthly Monthly
Total nitrogen mg/L Grab Monthly Monthly
pH pH units Grab Monthly Monthly
Standard minerals3 mg/L Grab Annually Annually

1. Sum of influent flows at the headworks and ARSA secondary effluent flows to the percolation ponds.

2. For continuous analyzers, the City shall document and report routine meter maintenance activities including date, time of day, and duration, in which the analyzer(s) is not in operation.

3. Standard minerals shall include, at a minimum, the following elements/compounds: arsenic, aluminum, boron, calcium, chloride, dissolved iron, magnesium, dissolved manganese, potassium, sodium, sulfate, total alkalinity (including alkalinity series), and hardness. 408
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE

HISTORICAL INFLUENT FLOWS
This section describes the historical flows from each source that contributes to the WWTF influent.

Total Influent Flows
Influent flows to the WWTF come from the following sources:
• Filter backwash from the Castle Oaks Water Reclamation Facility (COWRF) • Filter backwash from the Ione Water Treatment Plant (WTP), operated by the Amador Water Agency (AWA)
• Base City flows (i.e. wastewater from City sewer customers) • Wet weather flows, which including inflow and infiltration (I&I) to the wastewater collection system and tailwater runoff from the Town Field
The total historical average daily influent flows to the WWTF are shown in Table 6. The average annual flow (AAF) and ADWF to the WWTF for each year is also shown. 4 As shown, flows were significantly higher in the 2024 irrigation season as compared to previous years.

WWTF staff have reported that they suspect that during the 2024 irrigation season there was a leak in the valve that connects the COWRF and WWTF influent flow lines. This leak caused a portion of the flow sent from Preston Reservoir to enter the WWTF instead of the COWRF. This observation is supported by a review of the COWRF data that demonstrates the flow sent from Preston Reservoir was 100,000 to 300,000 gallons per day (gpd) higher than the reported COWRF influent flows. As discussed recently with the Regional Board staff, the City has identified the cause of the leak as a damaged seal in the drain valves in the chlorine contact basins. The City has fixed the issue. 4 The ADWF period is defined as July through September, consistent with the definition in the WDRs. 409
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Table 6. Historical Average WWTF Influent Flow
Month
Average Daily WWTF Influent Flow, mgd
2016 2017 2018 2019 2020 2021 2022 2023 2024
October 0.381 0.423 0.395 0.486 0.502 0.490 0.390 0.615 0.860 November 0.329 0.352 0.386 0.530 0.431 0.343 0.433 0.447 0.583 December 0.371 0.318 0.344 0.430 0.346 0.555 0.510 0.431 - January 0.433 0.656 0.406 0.480 0.399 0.412 0.451 0.894 0.545 February 0.386 0.582 0.353 0.805 0.361 0.434 0.396 0.575 0.723 March 0.474 0.454 0.609 0.790 0.460 0.351 0.395 0.939 0.656 April 0.364 0.422 0.471 0.495 0.473 0.395 0.546 0.582 0.590 May 0.375 0.375 0.438 0.546 0.538 0.395 0.485 0.607 0.849 June 0.406 0.381 0.404 0.470 0.562 0.462 0.457 0.597 0.839 July 0.386 0.418 0.333 0.355 0.563 0.520 0.454 0.578 0.784 August 0.395 0.453 0.247 0.447 0.554 0.505 0.474 0.656 0.897 September 0.413 0.490 0.375 0.517 0.536 0.465 0.409 0.616 0.894 AAF, mgd 0.393 0.444 0.397 0.529 0.477 0.444 0.450 0.628 0.747 ADWF, mgd 0.398 0.454 0.318 0.440 0.551 0.497 0.446 0.617 0.858 COWRF Backwash Flows
The COWRF provides tertiary recycled water to meet the irrigation demands of the Castle Oaks Golf Course (golf course). During the COWRF tertiary treatment process, a fraction of the flows through the COWRF is discarded as filter backwash and sent to the WWTF. Historical COWRF backwash flows are shown in Table 7. The COWRF ADWF for each year, which is used in calculating historical Base City flows, is also shown.
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Table 7. Historical COWRF Backwash Flow
Month
Volume of COWRF Backwash Flow, MG
2016 2017 2018 2019 2020 2021 2022 2023 2024
October 2.2 3.0 1.9 4.0 3.4 2.4 1.7 7.3
(a) 5.0
November 0 0 1.1 1.9 1.7 0 2.3 4.1(a) 1.7
December 0 0 0 0 0 0 0 0 -
January 0 0 0 0 0 0 0 0 0
February 0 0 0 0 0 0 0 0 0
March 0 0 0 0 0 0 0 0 0
April 0 0 0 0 0 2.0 2.0 0.1 0
May 1.7 2.2 2.5 1.9 2.7 3.9 1.9 3.0 2.2
June 3.6 3.4 3.6 2.5 3.8 3.4 2.0 3.7 3.6
July 3.4 4.7 4.4 3.9 3.6 4.0 2.7 4.4 3.8
August 3.7 4.2 3.9 3.9 4.3 3.8 2.7 5.4(a) 5.1
September 4.1 4.1 3.5 4.0 4.0 2.6 2.2 6.4
(a) 5.5
Total, MG 18.7 21.7 20.9 22.1 23.4 21.9 17.5 34.4 26.9
ADWF, mgd 0.122 0.141 0.128 0.128 0.129 0.113 0.083 0.158 0.157 (a) Backwash flows during this period were irregular due to filter maintenance. Values were not used in calculated average.

AWA Backwash Flows
The AWA discharges filter backwash flows from the Ione WTP to the City’s wastewater system. Historical monthly backwash flows from AWA are shown in Table 8. The AWA filter ADWF backwash for each year, which was used in calculating the historical Base City flows, is also shown.

AWA flows to the WWTF decreased significantly after the completion of a filter upgrade project in 2016.

Since then, intentional efforts have been made by AWA to further reduce flows. Between 2020 and 2021, the total volume of AWA flows sent to the WWTF decreased from 3.45 MG to 1.72 MG. Since 2021, total AWA flows to the WWTF have remained below 2 MG per year. 411
Section 13, Item J.

TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Table 8. Historical AWA Backwash Flow
Month
Volume of AWA Backwash Flow, MG
2016 2017 2018 2019 2020 2021 2022 2023 2024
October 0.10 0.13 0.27 0.13 0.32 0.14 0.02 0.24 0.53
November 1.56 0.47 0.05 0.62 0.27 0.06 0.14 0.16 0.31
December 1.66 0.26 0.11 0.11 0.50 0.23 0.08 0.19 -
January 1.23 1.72 0.51 0.32 0.35 0.15 0.06 0.16 0.10
February 1.08 0.29 0.41 0.23 0.38 0.21 0.05 0.04 0.29
March 0.09 0.10 0.40 0.01 0.21 0.16 0.05 0.04 0.21
April 0.48 0.09 0.09 0.50 0.30 0.29 0.22 0.04 0.20
May 0.34 0.28 0.40 0.59 0.40 0.10 0.06 0.34 0.22
June 0.10 0.29 0.51 0.50 0.33 0.11 0.06 0.06 0.09
July 0.29 0.27 0.25 0.32 0.05 0.14 0.13 0.06 0.43
August 0.13 0.16 0.14 0.18 0.18 0.06 0.30 0.08 0.19
September 0.05 0.57 0.24 0.02 0.16 0.07 0.03 0.28 0.17
Total, MG 7.11 4.60 3.38 3.53 3.45 1.72 1.20 1.69 1.90
ADWF, mgd 0.005 0.011 0.007 0.006 0.004 0.003 0.005 0.005 0.009 Base City Flows
The base flow for the City can be determined by subtracting COWRF and AWA backwash ADWFs from the WWTF ADWF. The calculated daily average Base City flows for 2016 through 2024 are shown in Table 9.

Table 9. Historical Base City Wastewater Flows
Year
ADWF, mgd
WWTF Influent
ADWF
COWRF Backwash
ADWF
AWA Backwash
ADWF
Base City
ADWF
2016 0.398 0.122 0.005 0.271
2017 0.454 0.142 0.011 0.301
2018 0.318 0.128 0.007 0.183
2019 0.440 0.128 0.006 0.306
2020 0.551 0.129 0.004 0.418
2021 0.497 0.113 0.003 0.381
2022 0.446 0.083 0.005 0.358
2023 0.617 0.158 0.005 0.454
2024 0.858 0.157 0.009 0.692
Average (2016-2023)(a) 0.465 0.125 0.006 0.334
(a) Averages exclude 2024 flow values due to the influence of Preston Reservoir flows being inadvertently directed to the WWTF. 412
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Wet Weather Flows
During wet weather months, I&I from the City’s collection system and collected tailwater runoff from the Town Field enter the WWTF. These flows have been calculated for each month by subtracting COWRF backwash flows, AWA backwash flows and base City flows from the total WWTF influent flow. For this analysis the monthly Base City flows were calculated by multiplying the Base City flow determined for each year, as presented in Table 9, by the number of days in each month. Calculated wet weather flows are presented in Table 10.

Table 10. Historical Wet Weather Flows
Month
Volume of Wet Weather Flows, MG(a)
2016 2017 2018 2019 2020 2021 2022 2023
October 1.1 0.6 4.4 1.5 0 0.8 0 0
November 0.2 1.0 4.9 4.2 0 0 0 0
December 1.4 0.2 4.9 3.7 0 5.2 4.6 0
January 3.8 9.2 6.4 5.1 0 0.8 2.8 13.5
February 2.1 7.6 4.3 13.7 0 1.3 1.0 3.3
March 6.2 4.6 12.8 15.0 1.1 0 1.1 15.0
April 2.3 3.5 8.5 5.2 1.4 0 3.4 3.7
May 1.2 0 5.0 5.0 0.6 0 2.0 1.4
June 0.3 0 2.5 1.9 0.2 0 0.9 0.5
July 0 0 0 0 0.8 0.2 0.1 0
August 0 0.3 0 0.3 0 0 0.6 0.8
September 0.1 1.0 2.0 2.3 0 0 0 0
Total 18.7 28.0 55.7 57.9 4.1 8.3 16.5 38.2
(a) Calculated wet weather flows include I&I and collected tailwater runoff from the Town Field. 413
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE

CLIMATE DATA
The California Department of Water Resources (DWR) has defined the average annual rainfall, 1-in-100-year annual rainfall, and the monthly distributions of rainfall based on rainfall data for the Ione National Climate Data Center (NCDC) weather station. These values are as follows:
• The average rainfall year was defined as having a total rainfall of 22.0 inches. • The 1-in-100 rainfall year was defined as having a total rainfall of 41.1 inches. • The monthly rainfall distribution values were defined based on the 1906 to 1997 “Normal” monthly values as calculated by the DWR.

Reference evapotranspiration (ET) for each month is based on long-term monthly average ET values for the Plymouth California Irrigation Management Information System (CIMIS) station, located approximately 13 miles northeast of the WWTF. This rainfall and reference ET information is presented in Table 11, based on the DWR information provided in Attachment C.

Table 11. Applicable Climate Data
Month
Average Rainfall,(a)
inches
1-in-100 Year Rainfall,
(a,b)
inches
Reference ET,
(c)
inches
October 1.15 2.15 3.24
November 2.81 5.24 1.68
December 3.53 6.58 1.21
January 5.08 9.48 1.48
February 3.14 5.86 1.95
March 3.19 5.95 3.02
April 1.75 3.26 4.57
May 0.63 1.18 5.97
June 0.23 0.43 7.19
July 0.07 0.13 7.64
August 0.13 0.24 6.98
September 0.33 0.62 4.99
Total 22.0 41.1 49.9
(a) Ione NCDC weather station #044283.
(b) Monthly 1-in-100 rainfall values are calculated from the total 1-in-100 year rainfall value and the ratio of average monthly rainfall to average total rainfall.
(c) Plymouth CIMIS station #227.
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
CURRENT (2024) INFLUENT FLOWS
This section presents the estimated current (2024) influent flows to the WWTF from each source. These flows will be used to develop the current condition water balances.

Current Base Flows
Equivalent dwelling unit (EDU) data was used to calculate the average daily Base City flow per EDU for each year. The number of EDUs and calculated Base City flow per EDU for each year are presented in Table 12.

Table 12. Development of Daily Average Base City Flow per EDU Year Number of EDUs Base City ADWF, mgd Flow per EDU, gpd/EDU 2016 1,825(a) 0.271 148
2017 1,899(b) 0.302 159
2018 1,973(b) 0.183 93
2019 2,047(c) 0.306 149
2020 2,269(d) 0.418 184
2021 2,208(d) 0.381 173
2022 2,373(d) 0.358 151
2023 2,481(d) 0.454 183
2024 2,520(d) 0.692 275
Average(e) 0.334 164
(a) From 2020 Expansion Completion Report by Dexter Wilson Engineering (2016). (b) The 2017 and 2018 EDU values were calculated by taking the difference between the reported 2019 and 2016 EDUs and distributing their addition across the three years.
(c) From 2021 Water Balance Update and 2020 Expansion Completion Report by Coastland Engineers. (d) From City Sewer January Billing Register for January of each year. (e) Averages exclude 2018 and 2024 flow values.

As previously noted, the WWTF influent flows in 2024 included flows from Preston Reservoir that were inadvertently discharged to the WWTF. Atypical flows in 2024 is further demonstrated by that fact that the ADWF per EDU in 2024 was almost twice the ADWF per EDU of the four years prior. Due to the uncertainty associated with estimating this atypical influent flow to the WWTF, 2024 Base City flows have been excluded from the water balance analysis.

In addition, the 2018 Base City flow per EDU of 93 gpd is also anomalous when compared with the Base City flows of past and future years. Therefore, the data from 2018 has also been excluded from the calculation of the average Base City flow per EDU.

With the two exclusions noted above, the data in Table 12 demonstrates that the overall average daily base flow per EDU for 2016 to 2023 was calculated to be 164 gpd per EDU. To define the current daily base flow for use in the calibrated water balance, the overall average daily base flow per EDU was multiplied by the number of EDUs in 2024. The current (2024) base flow is value is calculated to be

0.41 mgd.
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COWRF Backwash
The theoretical agronomic demands of the golf course, the COWRF influent rate needed to fulfill these demands, and the fraction of influent discarded as backwash were determined in the recently completed Castle Oaks Golf Course Recycled Water Demands TM, which is included as Attachment D. The calculated theoretical backwash flows will be used in the WWTF water balance analyses. The theoretical COWRF backwash flow for an average rainfall year is shown in Table 13. The theoretical COWRF backwash flow for a 1-in-100 rainfall year is shown in Table 14.

Table 13. Theoretical Monthly COWRF Backwash Flow for an Average Rainfall Year Month
Average-Year
COWRF Influent Flow,
acre-feet
COWRF Backwash Flow as a
Percentage of Influent Flow,
percent
Average-Year
COWRF Backwash to WWTF,
acre-feet
October 27.3 18 4.9
November 0 19 0
December 0 - 0
January 0 - 0
February 0 - 0
March 0 - 0
April 35.3 15 5.3
May 70.1 13 9.1
June 92.4 13 12.0
July 100.9 13 13.1
August 91.1 13 11.8
September 64.6 17 11.0
Total, AFY 481.7 - 67.2
Source: Castle Oaks Golf Course Recycled Water Demands TM, Table 11 AFY = acre-feet per year
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Table 14. Theoretical Monthly COWRF Backwash Flow for a 1-in-100 Rainfall Year Month
1-in-100-Year
COWRF Influent Flow,
acre-feet
COWRF Backwash Flow as a
Percentage of Influent Flow,
percent
1-in-100-Year
COWRF Backwash to WWTF,
acre-feet
October 11.3 18 2.0
November 0 19 0
December 0 - 0
January 0 - 0
February 0 - 0
March 0 - 0
April 11.9 15 1.8
May 61.7 13 8.0
June 89.4 13 11.6
July 99.9 13 13.0
August 89.4 13 11.6
September 59.9 17 10.2
Total, AFY 423.5 - 58.2
Source: Castle Oaks Golf Course Recycled Water Demands TM, Table 12 417
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AWA Backwash Flows
As previously noted, AWA flows to the WWTF decreased significantly since 2021. Therefore, AWA flow data from 2021 to 2024 were used as the basis for defining current AWA flows in the average water balances. Monthly AWA backwash flows from 2021 to 2024 are shown in Table 15. The average AWA backwash flow received was calculated for each month and was used directly in the average rainfall year and 1-in-100 rainfall year water balances.

Table 15. Historical AWA Backwash Flow
Month
Volume of AWA Backwash Flow, MG Average,
2021 2022 2023 2024 Average acre-feet
October 0.14 0.02 0.24 0.53 0.23 0.71
November 0.06 0.14 0.16 0.31 0.17 0.52
December 0.23 0.08 0.19 - 0.17 0.52
January 0.15 0.06 0.16 0.10 0.12 0.37
February 0.21 0.05 0.04 0.29 0.15 0.46
March 0.16 0.05 0.04 0.21 0.12 0.37
April 0.29 0.22 0.04 0.20 0.19 0.58
May 0.10 0.06 0.34 0.22 0.18 0.55
June 0.11 0.06 0.06 0.09 0.08 0.25
July 0.14 0.13 0.06 0.43 0.19 0.58
August 0.06 0.30 0.08 0.19 0.16 0.49
September 0.07 0.03 0.28 0.17 0.14 0.43
Total 1.72 1.20 1.69 2.74 1.90 5.83
Town Field Tailwater Runoff
The City is required to collect winter tailwater runoff from the Town Field and recirculate it to the headworks. However, the volume of tailwater collected is not measured before it is combined with the overall WWTF influent flow. Therefore, an estimate of runoff must be made (as noted above, this estimated is also used to define the I&I relationship). A modified rational method for calculating runoff based on precipitation and ET was used to estimate theoretical monthly runoff volumes for inclusion in the water balance using the following equations:

Runoff = Precipitation – Crop ET - Interception - Infiltration Infiltration = Infiltration Factor x (Precipitation – Crop ET - Interception) 418
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Monthly total precipitation and reference ET from the Plymouth CIMIS Station were used to calibrate the theoretical runoff calculation parameters.5 These values are presented in Table 16 and Table 17, respectively.

Table 16. Historical Monthly Precipitation
Year
Total Precipitation by Month, inches(a)
Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Total 2019 6.3 11.1 7.0 1.9 6.3 0 0 0 1.4 0 1.5 6.2 42
2020 2.2 0.0 6.4 3.3 2.5 0 0 0 0 0 1.8 1.8 18
2021 5.9 2.4 2.8 0.1 0.1 0 0 0 0 8.5 1.0 8.7 29
2022 0.3 0.1 1.0 3.9 0.1 0.3 0 0 0.7 0 0.5 15.9 23
2023 9.7 4.6 8.3 0.2 1.1 0.1 0 0 0.6 1.4 1.7 2.1 30
(a) Plymouth CIMIS station #227.

Table 17. Historical Monthly ET
Year
Total Reference ET by Month, inches(a)
Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Total 2019 1.8 1.6 3.0 4.6 5.0 7.2 7.8 7.1 4.9 3.9 2.2 1.5 50 2020 1.6 2.7 2.9 4.5 6.1 7.6 8.3 7.0 5.3 4.2 2.0 1.3 53 2021 1.4 2.0 3.4 5.5 7.2 7.8 8.4 7.1 4.4 1.1 1.3 0.8 50 2022 1.7 2.5 3.7 3.3 2.6 7.4 8.1 6.8 3.7 1.9 1.4 0.9 44 2023 1.3 1.7 2.3 5.0 5.8 6.7 8.5 7.3 4.7 3.6 2.0 1.2 50 (a) Plymouth CIMIS station #227.

The monthly crop ET was set equal to the monthly reference ET, as the alfalfa that is grown on the Town Field is typically assigned a crop coefficient of 1 (DWR, 2015).

Interception is the precipitation in inches captured on the vegetation, including the leaves and roots of the plants, and surface depressions in the soil. The calibrated interception value was determined to be 3 inches.

The formula for infiltration also includes an infiltration factor. Different infiltration factors were used for saturated and unsaturated soil conditions:
• For months with saturated soil conditions, an infiltration factor of 0.4 was used. • For months with unsaturated soil conditions, an infiltration factor of 0.6 was used. 5 The Ione NCDC weather station (#044283), which was used to define average and 1-in-100 year rainfall statistics previously in this TM is no longer an active station. Therefore, the Plymouth CIMIS station is the closest currently active rain gauge to the WWTF. Also, the Plymouth CIMIS station data does not have an adequate historical record to establish average and 1-in-100 year rainfall statistics. 419
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Soil conditions were considered saturated when the two-month cumulative precipitation was greater than 10 inches. The two-month cumulative precipitation was calculated as the sum of total precipitation in the previous and current month.

Finally, the City has the ability to shut off tailwater flow from the Town Field when rainfall is heavy and tailwater flows threaten to inundate the WWTF. Shutting off the return flow causes stormwater to accumulate on the field, allowing it to infiltrate over a longer period and reduce the total runoff volume to the WWTF. This has been the historical practice to avoid overwhelming the plant. To calibrate the runoff and I&I models (both of which depend on the same flow data), the maximum monthly precipitation cutoff value used to calculate runoff was set to 8 inches for any month where the total precipitation was greater than 8 inches. Using this cutoff value, the combined runoff and I&I models provided reasonable results (i.e. if the value was not cutoff, the I&I calculations would be under-estimated). A summary of the calculated historical Town Field Runoff is provided in Table 18.

Table 18. Estimated Historical Town Field Runoff
Year
Total Runoff by Month, acre-feet
Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Total 2019 2.8 4.0 2.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3.3 13.0 2020 0.0 0.0 0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.9 2021 2.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6.1 0.0 6.1 15.1 2022 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2023 7.2 0.0 7.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 14.3 As noted above, the historical values shown in Table 18 were used to define the I&I relationship.

However, holding runoff on the Town Field may have historically resulted in runoff leaving the site.

Therefore, the practice of holding runoff on the Town Field is not included in the analysis of future conditions. To address this in the water balance model, the minimum rainfall cutoff value was set to 20 inches, which far exceeds the monthly rainfall for any month. Therefore, the model effectively ignores this cutoff value6.

A summary of the parameters used to calculate the theoretical tailwater runoff flows is shown in Table 19.

The theoretical Town Field tailwater runoff for an average rainfall year is shown in Table 20. The theoretical Town Field tailwater runoff for a 1-in-100 rainfall year is shown in Table 21. 6 The runoff cap feature of the model was retained in the event the model is used in the future where runoff capture is improved/allowed.
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February 26, 2025

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Table 19. Summary of Tailwater Runoff Calculation Parameters Parameter Value
Interception, inches 3
Two-Month Cumulative Precipitation to Saturate Soil, inches 10 Unsaturated Soil Infiltration Factor 0.4
Saturated Soil Infiltration Factor 0.6
Maximum Monthly Precipitation Used to Calculate Runoff, inches 20(a) (a) The calibrated value was 8 inches. However, future models apply 20 inches of rainfall, which far exceeds monthly rainfall values and is effectively negates the storage of runoff on the Town Field. The monthly maximum rainfall cutoff value is retained in the model in the event effective runoff capture is developed in the future.

Table 20. Theoretical Monthly Town Field Tailwater Runoff for an Average Rainfall Year Month
Average Year
Rainfall, inches(a)
ET,
inches(a)
Theoretical
Infiltration, inches
Theoretical
Runoff, inches
Theoretical
Runoff, acre-feet
October 1.15 3.24 0 0 0
November 2.81 1.68 0 0 0
December 3.54 1.21 0 0 0
January 5.09 1.48 0.36 0.24 3.5
February 3.14 1.95 0 0 0
March 3.2 3.02 0 0 0
April 1.75 4.57 0 0 0
May 0.63 5.97 0 0 0
June 0.23 7.19 0 0 0
July 0.07 7.64 0 0 0
August 0.13 6.98 0 0 0
September 0.33 4.99 0 0 0
Total 22.0 49.9 0.36 0.24 3.5
(a) From Table 11.
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Table 21. Theoretical Monthly Town Field Tailwater Runoff for a 1-in-100 Rainfall Year Month
1-in-100 Year
Rainfall,
inches(a) ET, inches(a)
Theoretical
Infiltration,
inches
Theoretical
Runoff,
inches
Theoretical
Runoff, acrefeet
Theoretical
Runoff
without
Rainfall Cap,
acre-feet
October 2.15 3.24 0 0 0 0
November 5.24 1.68 0.3 0.2 3.3 3.3
December 6.58 1.21 0.9 1.4 20.7 20.7
January 9.48 1.48 2.0 3.0 22.2 43.7
February 5.86 1.95 0.4 0.5 8.0 8.0
March 5.95 3.02 0 0 0 0
April 3.26 4.57 0 0 0 0
May 1.18 5.97 0 0 0 0
June 0.43 7.19 0 0 0 0
July 0.13 7.64 0 0 0 0
August 0.24 6.98 0 0 0 0
September 0.62 4.99 0 0 0 0
Total 41.1 49.9 3.6 3.7 54.2 75.7
(a) From Table 11.

Inflow and Infiltration
Theoretical I&I into the City collection system was determined using a linear regression analysis of historical WWTF influent and climate data. Monthly data from 2019 to 2023 was analyzed. For each wet weather month, defined as November to April, monthly I&I was calculated using the following equation:

I&I = WWTF Influent - Base City Flow - AWA Backwash - Estimated Town Field Runoff If the calculated I&I for any month was less than zero, that month was excluded from the analysis. The average daily I&I for each month was calculated by dividing the monthly I&I by the number of days in the month.

For each month, the average daily precipitation was calculated by dividing the monthly precipitation by the number of days in the month. The two-month average precipitation was calculated as the sum of the daily average precipitation of the previous and current month. 422
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February 26, 2025

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The average daily I&I and two-month average precipitation were plotted for each month and used to calculate a linear equation. The plotted data and corresponding equation are shown on Figure 4.

Figure 4. Two-Month Average Precipitation versus Daily Average I&I per Month The slope and intercept from the linear regression equation were used to calculate the theoretical I&I for each month as a function of the two-month cumulative precipitation. The theoretical monthly I&I for an average rainfall year is shown in Table 22. The theoretical monthly I&I for a 1-in-100 rainfall year is shown in Table 23.

I&I is assumed to not increase appreciably with expansion of the City collection system in the next 5 years, as new infrastructure is less susceptible to I&I. Therefore, the same I&I was used for the current and Year 2030 water balance models.
y = 0.5394x - 0.0122
R² = 0.5882

0.0 0.1

0.2 0.3

0.4 0.5

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Monthly Average Inflow & Infiltration, mgd
Two Month Average Precipitation, in/day
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Table 22. Theoretical Monthly I&I Flows for an Average Rainfall Year Month
Average Year Rainfall,
inches(a)
Theoretical I&I,
mgd
Theoretical I&I,
acre-feet
October 1.15 0.61 1.9
November 2.81 1.50 4.6
December 3.54 1.89 5.8
January 5.09 2.73 8.4
February 3.14 1.68 5.2
March 3.2 1.71 5.2
April 1.75 0.93 2.9
May 0.63 0.33 1.0
June 0.23 0.11 0.3
July 0.07 0.03 0.1
August 0.13 0.06 0.2
September 0.33 0.17 0.5
Total 22.0 11.8 36.1
(a) From Table 11.

Table 23. Theoretical Monthly I&I Flows for a 1-in-100 Rainfall Year Month
1-in-100 Year Rainfall,
inches(a)
Theoretical I&I,
inches
Theoretical I&I,
acre-feet
October 2.15 1.15 3.5
November 5.24 2.81 8.6
December 6.58 3.53 10.8
January 9.48 5.10 15.7
February 5.86 3.15 9.7
March 5.95 3.20 9.8
April 3.26 1.75 5.4
May 1.18 0.62 1.9
June 0.43 0.22 0.7
July 0.13 0.06 0.2
August 0.24 0.12 0.4
September 0.62 0.32 1.0
Total 41.1 22.0 67.7
(a) From Table 11.
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Total Influent Flows
The current theoretical influent flows to the WWTF used for the average rainfall year and 1-in-100 rainfall year water balances are presented in Table 24 and Table 25, respectively. As shown, the current ADWF is estimated to be approximately 0.55 mgd.

Table 24. Current Theoretical Influent Flows for an Average Rainfall Year Month
Inflows, acre-feet
Base City I&I Field Runoff
COWRF
Backwash AWA Backwash Total
October 39.3 1.9 0 4.9 0.71 46.8
November 38.0 4.6 0 0 0.52 43.1
December 39.3 5.8 0 0 0.52 45.6
January 39.3 8.4 3.5 0 0.37 51.6
February 35.5 5.2 0 0 0.46 41.2
March 39.3 5.2 0 0 0.37 44.9
April 38.0 2.9 0 5.3 0.58 46.8
May 39.3 1.0 0 9.1 0.55 50.0
June 38.0 0.3 0 12.0 0.25 50.6
July 39.3 0.1 0 13.1 0.58 53.1
August 38.0 0.2 0 11.8 0.49 50.5
September 39.3 0.5 0 11.0 0.43 51.2
Total, AFY 462.6 36.1 3.5 67.2 5.83 575.2
AAF, mgd 0.41 0.032 0.003 0.060 0.005 0.51
ADWF, mgd 0.41 0.003 0 0.127 0.005 0.55
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Table 25. Current Theoretical Influent Flows for a 1-in-100 Rainfall Year Month
Inflows, acre-feet
Base City I&I Field Runoff
COWRF
Backwash AWA Backwash Total
October 39.3 3.5 0 2 0.71 45.5
November 38.0 8.6 3.3 0 0.52 50.4
December 39.3 10.8 20.7 0 0.52 71.3
January 39.3 15.7 43.7 0 0.37 99.1
February 35.5 9.7 8 0 0.46 53.7
March 39.3 9.8 0 0 0.37 49.5
April 38.0 5.4 0 1.8 0.58 45.8
May 39.3 1.9 0 8 0.55 49.8
June 38.0 0.7 0 11.6 0.25 50.6
July 39.3 0.2 0 13 0.58 53.1
August 38.0 0.4 0 11.6 0.49 50.5
September 39.3 1.0 0 10.2 0.43 50.9
Total, AFY 462.6 67.7 54.2 58.2 5.83 670.0
AAF, mgd 0.41 0.06 0.048 0.052 0.005 0.60
ADWF, mgd 0.41 0.006 0 0.123 0.005 0.55
PROJECTED 2030 INFLUENT FLOWS
The City reports that 75 to 100 homes per year are expected to be built in each of the next 5 years. The projected number of EDUs for 2025 through 2030 was calculated by conservatively adding 100 EDUs for each year to the reported 2,520 EDUs in January 2024. The projected daily Base City flow for each year was calculated by multiplying the number of EDUs by the calculated average daily base flow per EDU of 164 gpd per EDU (from Table 12). The projected Base City flows are summarized in Table 26.

Table 26. Projected Base City Flows
Year Projected Number of EDUs Projected Base City Flow, mgd(a) 2025 2,620 0.43
2026 2,720 0.45
2027 2,820 0.46
2028 2,920 0.48
2029 3,020 0.50
2030 3,120 0.51
(a) Projected Base City Flow = (Projected Number of EDUs) x (Average Daily Base Flow of 164 gpd per EDU). 426
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February 26, 2025

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The projected Year 2030 theoretical influent flows to the WWTF used for the average rainfall year and 1-in-100 rainfall year water balances are presented in Table 27 and Table 28, respectively. As shown, the projected 2030 ADWF is approximately 0.65 mgd7.

Table 27. Projected 2030 Influent Flows for an Average Rainfall Year Month
Inflows, acre-feet
Base City I&I Field Runoff
COWRF
Backwash AWA Backwash Total
October 48.5 1.9 0 4.9 0.71 56.0
November 47.0 4.6 0 0 0.52 52.1
December 48.5 5.8 0 0 0.52 54.8
January 48.5 8.4 3.5 0 0.37 60.8
February 43.8 5.2 0 0 0.46 49.5
March 48.5 5.2 0 0 0.37 54.1
April 47.0 2.9 0 5.3 0.58 55.8
May 48.5 1.0 0 9.1 0.55 59.2
June 47.0 0.3 0 12.0 0.25 59.6
July 48.5 0.1 0 13.1 0.58 62.3
August 47.0 0.2 0 11.8 0.49 59.5
September 48.5 0.5 0 11.0 0.43 60.4
Total, AFY 571.0 36.1 3.5 67.2 5.83 683.9
AAF, mgd 0.51 0.032 0.003 0.060 0.005 0.61
ADWF, mgd 0.51 0.003 0 0.127 0.005 0.65
7 It is noted that this flow is lower than the current estimated treatment capacity for the WWTF including Pond 5. As noted, this capacity will be confirmed through future analyses and submitted to the Regional Board. 427
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February 26, 2025

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Table 28. Projected 2030 Influent Flows for a 1-in-100 Rainfall Year Month
Inflows, acre-feet
Base City I&I Field Runoff
COWRF
Backwash AWA Backwash Total
October 48.5 3.5 0 2.0 0.71 54.7
November 47.0 8.6 3.3 0 0.52 59.4
December 48.5 10.8 20.7 0 0.52 80.5
January 48.5 15.7 43.7 0 0.37 108.3
February 43.8 9.7 8 0 0.46 62.0
March 48.5 9.8 0 0 0.37 58.7
April 47.0 5.4 0 1.8 0.58 54.8
May 48.5 1.9 0 8.0 0.55 59.0
June 47.0 0.7 0 11.6 0.25 59.6
July 48.5 0.2 0 13.0 0.58 62.3
August 47.0 0.4 0 11.6 0.49 59.5
September 48.5 1.0 0 10.2 0.43 60.1
Total, AFY 571.0 67.7 54.2 58.2 5.83 778.7
AAF, mgd 0.51 0.06 0.048 0.052 0.005 0.70
ADWF, mgd 0.51 0.006 0 0.123 0.005 0.64

ESTIMATED CAPACITY OF EXISTING DISCHARGE AREAS
This section describes the procedures used to calculate the theoretical capacity of the WWTF disposal areas. As previously noted, the WWTF currently relies on two ways to discharge effluent: land application and percolation.

Land Application Area Irrigation Demands
During the summer irrigation season, the WWTF sends secondary effluent to two LAAs, the 57-acre Town Field and 5.6-acre City Field. The capacity of the LAAs to accept flows is limited by the crop irrigation demands8. The theoretical irrigation demand of each LAA for an average rainfall year was calibrated using historical monthly irrigation demand values. The historical monthly irrigation demands for the Town and City Fields are shown in Table 29 and Table 30.
8 It
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February 26, 2025

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Table 29. Historical Town Field Irrigation Demands
Month
Volume of Secondary Effluent Used, MG Average,
2019 2020 2021 2022 2023 2024 Average acre-feet
October 0 0 0 7.3 0 1.2 1.4 4.3
November 0 0 0 0 0 2.3 0.4 1.2
December 0 0 0 0 0 0 0 0
January 0 0 0 0 0 0 0 0
February 0 0 0 0 0 0 0 0
March 0 0 0 0 0 0 0 0
April 0 0 3.6 0 0 0 0.6 1.8
May 0 0 1.0 0 0 0 0.2 0.6
June 2.6 4.7 7.8 8.6 0.3 5.7 5.0 15.4
July 3.2 5.4 3.7 4.6 1.8 7.9 4.4 13.5
August 4.6 6.9 7.3 4.4 5.2 12.8 6.9 21.2
September 1.3 5.3 4.6 1.0 4.6 5.9 3.8 11.7
Total 11.7 22.3 28 25.9 11.9 35.8 22.7 69.7
Table 30. Historical City Field Irrigation Demands
Month
Volume of Secondary Effluent Used, MG Average,
2018 2019 2020 2021 2022 2023 Average acre-feet
October 0 0 0 0 0.5 0 0.1 0.3
November 0 0 0 0 0 0 0 0
December 0 0 0 0 0 0 0 0
January 0 0 0 0 0 0 0 0
February 0 0 0 0 0 0 0 0
March 0 0 0 0 0 0 0 0
April 0 0 0 0 0 0 0 0
May 0.4 0 0 0 0 0 0.1 0.3
June 0.3 0.3 0.2 0.3 0.9 0.4 0.4 1.2
July 0.5 0.7 0.2 0.3 0
(a) 0.3 0.4 1.2
August 0.6 0.3 0.4 0.7 0
(a) 0.8 0.6 1.8
September 0.3 0.1 0.7 0.8 0
(a) 1 0.6 1.8
Total 2.1 1.4 1.5 2.1 1.4 2.5 2.2 6.6
(a) Values excluded from average. Effluent was not sent to the City Field during this period due to circumstances unrelated to irrigation demand.
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February 26, 2025

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Theoretical irrigation demands are calculated using the following formula:

Irrigation Demand = (Crop ET - Precipitation) / Crop Area / Irrigation Efficiency The crop ET is calculated by multiplying the Reference ET shown in Table 11 by a representative crop coefficient. Crop coefficients for alfalfa crops such as those grown on the Town and City Fields are typically close to 1 (DWR, 2015). Irrigation efficiencies for hand-move spray irrigation systems like that used on the Town and City Fields can range from 60 to 80 percent (see Attachment E, Table 8.2b).

The theoretical irrigation demand can be calibrated by adjusting the irrigation efficiency value until the theoretical demand matches the historical irrigation volume supplied. However, assuming the highest irrigation efficiency value of 80 percent, the crop coefficient required to match the theoretical irrigation demand to historical irrigation volumes for the Town and City Fields was 0.32. These findings suggest that either (a) the historical reported irrigation flows are not accurate and/or (b) the fields are being irrigated well below agronomic rates (which would be the case if the field is not well drained). Given the uncertainty with the irrigation efficient values, it is suspected that the irrigation demands of the Town and City Fields are likely in between the historical irrigation demands and theoretical irrigation demands calculated with a crop coefficient of 1.

Discussions with City staff indicate that there is very little flow directed to the percolation basins during the summer irrigation season, suggesting that most of the flow is sent to the Town Field and City Field.

This would not be the case if the crop coefficient was 0.32. Therefore, the water balance models were developed using two different methods:

Using the theoretical irrigation demand calculated with the calibrated crop coefficient of 0.32.

Using theoretical irrigation demand calculated with a crop coefficient of 1.

A comparison of these values with historical irrigation volumes for the Town Field is presented in Table 31 and for the City Field in Table 32. It is also noted that the City is planning to replace the effluent flow meter for the Town Field prior to the initiation of the 2025 irrigation season to allow for ongoing assessment of the crop coefficient and irrigation demands to be made. 430
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Table 31. Historical and Theoretical Town Field Irrigation Demand Month
Historical Average
Irrigation Volume,
acre-feet
Theoretical Irrigation Demand, acre-feet(a)
Calculated with Crop
Coefficient of 0.32
Calculated with Crop
Coefficient of 1
October 4.3 4.0 12.4
November 1.2 0 0
December 0 0 0
January 0 0 0
February 0 0 0
March 0 0 0
April 1.8 5.4 16.7
May 0.6 10.1 31.7
June 15.4 13.2 41.3
July 13.5 14.4 44.9
August 21.2 13.0 40.7
September 11.7 8.9 27.7
Total, AFY 69.7 69.0 215.5
(a) Theoretical irrigation demand for an average rainfall year.

Table 32. Historical and Theoretical City Field Irrigation Demand Month
Historical Average
Irrigation Volume,
acre-feet
Theoretical Irrigation Demand, acre-feet(a)
Calculated with Crop
Coefficient of 0.32
Calculated with Crop
Coefficient of 1
October 0.3 0.4 1.2
November 0 0 0
December 0 0 0
January 0 0 0
February 0 0 0
March 0 0 0
April 0 0.5 1.6
May 0.3 1.0 3.1
June 1.2 1.3 4.1
July 1.2 1.4 4.4
August 1.8 1.3 4.0
September 1.8 0.9 2.7
Total, AFY 6.6 6.8 21.2
(a) Theoretical irrigation demand for an average rainfall year. 431
Section 13, Item J.

TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Percolation Ponds Percolation Rates
Effluent flows that exceed the demand of the LAAs are currently disposed of via percolation in Ponds 6 and 7. The capacity of the percolation ponds to accept flows is limited by the sustained percolation rate.

As noted in the December 12 Water Balance TM, a percolation rate for Ponds 6 and 7 was estimated using a water balance approach around the ponds. This analysis demonstrated that the ponds have a sustained percolation rate of 3.0 inches per day in months where saturated soil conditions were likely to occur (February through May) and a percolation rate of 3.6 inches per day in other months (June through January). However, as required by Regional Board staff, the water balances presented herein do not account for any percolation disposal in the ponds to reflect the requirements of the CDO.

OPERATIONAL ASSUMPTIONS
This section addresses the operational assumptions applied in developing the water balances.

Pond 5
As previously noted, the City currently operates Pond 5 as a treatment pond, where it is used to equalize flows prior to discharge to the percolation ponds and LAAs. For purposes of the water balance, monthly net storage volumes for Pond 5 were matched to historical monthly storage volumes over the past five years. The average monthly Pond 5 storage volumes from 2019 to 2023 are shown in Table 33. 9 The overall
average storage volume was calculated for each month and used in the water balances.

Table 33. Historical Pond 5 Storage
Month
Monthly Pond 5 Storage Volume, acre-feet
2019 2020 2021 2022 2023 Average
October 32.1 37.1 38.5 35.9 41.7 37.1
November 30.6 23.3 38.9 36.2 30 31.8
December 32.7 23.5 36.9 38.3 11.3 28.5
January 37.1 33.0 25.8 35.2 36.6 33.5
February 38.3 33.2 26.8 34.9 40.4 34.7
March 39.9 33.6 27.3 34.3 41.2 35.3
April 38.8 39.9 32.2 38.6 41.5 38.2
May 37.8 39.0 37.4 37.1 40.1 38.3
June 32.7 27.7 30.8 29.3 31.5 30.4
July 15.6 34.8 26.4 23.4 34.3 26.9
August 29.9 20.4 14.7 31.8 41.7 27.7
September 34.1 29.3 19.2 36.7 41.7 32.2
9 A volume-to-depth curve was used to calculate the storage volume of Pond 5 from weekly freeboard measurements. The monthly averages of the calculated storage volumes are shown in Table 33. 432
Section 13, Item J.

TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Ponds 6 and 7
The analysis assumes that both Ponds 6 and 7 are emptied in October to another storage location (not yet defined). Each month thereafter, flows that exceed the storage/evaporative capacity of the two ponds are also assumed to be directed to the same storage location.

WATER BALANCE RESULTS
Water balance models were developed for the current and projected 2030 flow conditions assuming the disposal capacity provided by percolation ponds is eliminated and the ponds are converted to storage. To provide a better understanding of the range of potential operating conditions, models were developed for the following scenarios:
• Average rainfall year and crop coefficient of 0.32 for the Town and City Fields10 • Average rainfall year and crop coefficient of 1 for the Town and City Fields11 • 1-in-100 rainfall year and crop coefficient of 0.32 for the Town and City Fields • 1-in-100 rainfall year and crop coefficient of 1 for the Town and City Fields The results of the water balances are summarized for the current flow conditions in Table 34 and for the 1-in-100 yar conditions in Table 35. Additional details are provided in Attachment F. Key findings from this analysis are as follows:
• At current City Base Flows of 0.41 mgd, the City would have an excess of up to 594 acrefeet of water that requires storage and/or disposal if the percolation ponds were lined. • At projected 2030 City Base Flows 0.51 mgd, an excess of up to 697 acre-feet of water would require storage and/or disposal if the percolation ponds were lined12.

As a final note, Regional Board staff have requested that the City consider the sensitivity of the water balance to the distribution of rainfall. For this analysis, the existing facilities do not provide adequate capacity for storage and disposal and there is excess water each month. Given this, the amount of excess flow generated in each month will not impact the results of the analysis. 10 The recent data suggests an unusually low crop coefficient for the Town and City Fields. Additional data collection is needed to confirm the value.
11 A crop coefficient of 1 would be typical for the types of crops grown on the City and Town Fields. 12 As discussed in the December Water Balance TM, the existing disposal capacity provided at the WWTF with the observed percolation rates is approximately 0.75 mgd ADWF. Therefore, there is no immediate risk of overflow based on the current configuration.
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TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE
Table 34. Summary of Current Water Balance Results, No Percolation Scenario
Base
City
Flow,
mgd
Total
WWTF
Inflows,
AFY
Irrigation, AFY Pond 6 & 7 Flows, AFY
Excess
Flow to
Additional
Storage,
Town Field DemandTown Field ProvidedCity
AFY
Field
DemandCity Field ProvidedPond 7 InflowsPond 7 OutflowsPond 6 InflowsPond 6 Outflows Average Rainfall Year
Crop Coeff.
of 0.32

0.41 572.0
69 69 7 7 474 0 462 0 453
Crop Coeff.
of 1
215 215 21 21 313 0 301 0 292
1-in-100 Rainfall Year
Crop Coeff.
of 0.32

0.41 666.8
62 62 6 6 600 0 597 0 594
Crop Coeff.
of 1
193 193 19 19 457 0 454 0 451
Table 35. Summary of 2030 Water Balance Results, No Percolation Scenario
Base
City
Flow,
mgd
Total
WWTF
Inflows,
AFY
Irrigation, AFY Pond 6 & 7 Flows, AFY
Excess
Flow to
Additional
Storage,
Town Field DemandTown Field ProvidedCity
AFY
Field
DemandCity Field ProvidedPond 7 InflowsPond 7 OutflowsPond 6 InflowsPond 6 Outflows Average Rainfall Year
Crop Coeff.
of 0.32

0.51 683.9
69 69 7 7 586 0 574 0 563
Crop Coeff.
of 1
215 215 21 21 425 0 413 0 403
1-in-100 Rainfall Year
Crop Coeff.
of 0.32

0.51 778.7
62 62 6 6 703 0 700 0 693
Crop Coeff.
of 1
193 193 19 19 559 0 556 0 550
434
Section 13, Item J.

TM – City of Ione
February 26, 2025

N-C-988-50-24-10-WP-CITY OF IONE WATER BALANCE

REFERENCES
California Department of Water Resources (DWR) and University of California, Davis, 2015. Consumptive Use Program Plus (CUP+) Model, Version 6.1. Accessed at https://water.ca.gov/Programs/Water-Use-AndEfficiency/Land-And-Water-Use/Agricultural-Water-Use-Models on December 11, 2024.

Central Valley Regional Water Quality Control Board, 2014a. Cease and Desist Order R5-2014-0157 for City of Ione Wastewater Treatment Facility, Amador County. December 2014.

Central Valley Regional Water Quality Control Board, 2014b. Revised Monitoring and Reporting Program R5-2013- 0022 (Rev 1) for City of Ione and Greenrock Ranch Lands, LLC., Ione Wastewater Treatment Facility, Amador County. December 2014.

Central Valley Regional Water Quality Control Board, 2014c. Waste Discharge Requirements Order R5-2013-0022- 001 for City of Ione and Greenrock Ranch Lands, LLC., Ione Wastewater Treatment Facility, Amador County. December 2014.

Coastland Engineers, 2021. City of Ione Water Balance Update and 2020 Capacity Expansion Completion Report.

March 2021
Dexter Wilson Engineering, Inc., 2016. City of Ione 2020 Capacity Expansion Completion Report. December 2016.

Lee & Ro, Inc. and PMC, 2009. City of Ione Wastewater Master Plan. December 2009.

Lee & Ro, Inc., 2010. Ione Water Reclamation Facility Report of Waste Discharge. March 2010.

GHD Inc., 2012a. City of Ione Revised Report of Waste Discharge. September 2012.

GHD Inc., 2012b. City of Ione Supplement to the Revised Report of Waste Discharge. November 2012.

U.S. Environmental Protection Agency, 2011. Principles of Wastewater Treatment Pond Systems for Plant Operators, Engineers, and Managers. August 2011.
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Groundwater Gradient Maps
Attachment A
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!>!>
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!> !>
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267.5'
262.5'
255'
250'
260'
Castle Oaks gradient
~0.004 ft/ft
WW TF grad ient
~0.0 04 ft/ft
252.5'
257.5'
265'
270'
255'
260'
257.5'
262.5'
265'
MW-1
GWE: 265.55'
MW-1A
GWE: 265.30'
MW-2
GWE:
258.95'
MW-2A
GWE: 260.54'
MW-3
GWE: 255.57'
MW-3A
GWE: 257.45'
MW-4
GWE: 258.17'
MW-4A
GWE: 258.42'
MW-5A
GWE:
260.02'
MW-08-1
GWE: 255.93'
MW-08-2A
GWE: 252.81'
MW-08-2B
GWE: 258.10'
MW-08-3
GWE: 265.34'
MW-08-4A
GWE: 267.49'
MW-08-4B
GWE: 267.47'
P1
GWE:
264.11'
P2
GWE: 264.10'
P3
GWE:
259.11'
P5B
GWE:
260.01'
CO MW-1
GWE: 271.70'
CO MW-2
GWE:
260.81'
CO MW-3
GWE: 257.01'
CO P-1
GWE: 252.21'
CO P-2
GWE: 249.48'
CO P-4
GWE: 249.46'
Source: Esri, Maxar, Earthstar Geographics, and the
0 500 1,000
Feet
Groundwater Elevation Map
o Prepared By
Ione WWTF & Castle Oaks Golf Course 3/28/2023 G:\Dellavalle-1020\102022001-Ione WWTP & Castle Oak GW Consulting\400 GIS\Map\1Q2023_GW_elevation_map.mxd Groundwater elevation (GWE) calculated from
depth to water measured on 3/02/2023.
!> Castle Oaks Golf Course
Flow Direction
GW Elevation Contour
!> Ione WWTF
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265.0'
255.0'
250.0'
265.0'
Castle Oaks
Gradient
257.5'
~0.005 ft/ft
WWTP
Gradient
~0.004 ft/ft
270.0'
252.5' 260.0'
262.5'
255.0'
252.5'
250.0'
257.5'
260.0'
262.5'
267.5'
270.0'
267.5'
MW-1
GWE: 265.22'
MW-1A
GWE: 264.64'
MW-2
GWE:
257.92'
MW-2A
GWE: 259.63'
MW-3
GWE:
254.74'
MW-3A
GWE:
256.31'
MW-4
GWE: 257.78'
MW-4A
GWE: 258.12'
MW-5A
GWE: 259.91'
MW-08-1
GWE: 255.61'
MW-08-2A
GWE: 253.30'
MW-08-2B
GWE: 257.37'
MW-08-3
GWE: 264.96'
MW-08-4A
GWE: 267.35'
MW-08-4B
GWE: 267.34'
P1
GWE: 264.61'
P2
GWE:
262.46'
P3
GWE:
260.44'
P5B
GWE:
259.90'
CO MW-1
GWE: 271.56'
CO MW-2
GWE: 259.89'
CO MW-3
GWE: 255.12'
CO P-1
GWE: 250.67'
CO P-2
GWE: 247.71'
CO P-4
GWE: 247.82'
Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community 0 500 1,000
Feet
Groundwater Elevation Map
o Prepared By
Ione WWTF & Castle Oaks Golf Course 4/23/2024 G:\Dellavalle-1020\102022001-Ione WWTP & Castle Oak GW Consulting\400 GIS\Map\1Q2024_GW_elevation_map.mxd Groundwater elevation (GWE) calculated from
depth to water measured on 2/28/2024.
!> Castle Oaks Golf Course
!> Ione WWTF
Flow Direction
GW Elevation Contour
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Jackson Rancheria Water Balance Certification Letter
Attachment B
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Rainfall and Reference ET Data
Attachment C
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Section 13, Item J.

IONE, CALIFORNIA (044283)
Period of Record Monthly Climate Summary
Period of Record : 03/01/1906 to 06/30/1977
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Average Max.

Temperature (F) Insuff icient Data
Average Min.

Temperature (F) Insuff icient Data
Average Total
Precipitation (in.) 5.08 3.14 3.19 1.75 0.63 0.23 0.07 0.13 0.33 1.15 2.81 3.53 22.04 Average Total
SnowFall (in.) 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 Average Snow Depth
(in.) 0 0 0 0 0 0 0 0 0 0 0 0 0
Percent of possible observations for period of record.

Max. Temp.: 0% Min. Temp.: 0% Precipitation: 99.9% Snowfall: 99.9% Snow Depth: 99.8% Check Station Metadata or Metadata graphics for more detail about data completeness.

Western Regional Climate Center, [email protected]
10/10/24, 2:42 PM IONE, CALIFORNIA Period of Record Monthly Climate Summary https://wrcc.dri.edu/cgi-bin/cliRECtM.pl?ca4283 1/1
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Rainfall Depth Duration Frequency at Ione
Station Number Station County Latitude Longitude Elevation Years Recorded B00 4283 00 Ione Amador 38.348 -120.938 284.0 89
Rainfall Statistics 1-Day 2-Day 3-Day 4-Day 5-Day 6-Day 8-Day 10-Day 15-Day 20-Day 30-Day 60-Day 1-Year Pr=0.5 1.92 2.55 3.01 3.38 3.70 3.99 4.48 4.91 5.79 6.51 7.68 10.19 21.28 Pr=0.2 2.55 3.37 3.98 4.47 4.89 5.27 5.92 6.48 7.64 8.58 10.11 13.39 27.84 Pr=0.1 2.92 3.87 4.55 5.11 5.60 6.02 6.76 7.40 8.71 9.78 11.52 15.23 31.54 Pr=0.04 3.36 4.44 5.22 5.86 6.40 6.89 7.73 8.45 9.94 11.16 13.13 17.32 35.70 Pr=0.02 3.66 4.83 5.67 6.36 6.96 7.48 8.39 9.17 10.78 12.09 14.22 18.74 38.51 Pr=0.01 3.94 5.19 6.10 6.84 7.47 8.04 9.01 9.84 11.57 12.97 15.23 20.06 41.11 Pr=0.005 4.21 5.54 6.51 7.29 7.96 8.56 9.59 10.48 12.31 13.79 16.19 21.31 43.57 Pr=0.002 4.54 5.97 7.01 7.85 8.58 9.22 10.33 11.28 13.23 14.82 17.40 22.87 46.64 Pr=0.001 4.79 6.29 7.38 8.26 9.02 9.69 10.85 11.85 13.90 15.57 18.26 23.99 48.84 Pr=0.0001 5.53 7.26 8.50 9.52 10.39 11.15 12.48 13.62 15.96 17.87 20.94 27.46 55.66 Annual Maxima 1-Day 2-Day 3-Day 4-Day 5-Day 6-Day 8-Day 10-Day 15-Day 20-Day 30-Day 60-Day 1-Year 2007 --- --- --- --- --- --- --- --- --- --- --- --- --- 2006 --- --- --- --- --- --- --- --- --- --- --- --- --- 2005 --- --- --- --- --- --- --- --- --- --- --- --- --- 2004 --- --- --- --- --- --- --- --- --- --- --- --- --- 2003 --- --- --- --- --- --- --- --- --- --- --- --- --- 2002 --- --- --- --- --- --- --- --- --- --- --- --- --- 2001 --- --- --- --- --- --- --- --- --- --- --- --- --- 2000 1.85 2.80 4.29 4.74 4.99 4.99 5.22 5.79 7.52 9.05 10.35 11.82 21.39 1999 2.02 2.44 3.42 3.42 3.42 3.42 3.42 4.17 5.51 5.72 8.41 10.90 15.39 1998 2.37 3.55 4.11 4.36 4.98 5.85 6.61 7.31 8.07 10.05 14.21 21.25 30.46 1997 2.37 3.55 4.11 4.36 4.98 5.85 6.61 7.31 8.07 10.05 14.21 21.25 43.59 1996 3.75 3.85 3.85 3.85 3.85 3.85 3.85 3.85 4.74 5.27 6.16 11.53 22.80 1995 2.90 4.71 5.05 5.33 5.58 5.71 7.45 8.02 9.08 9.83 12.42 16.90 35.50 1994 1.27 1.70 1.95 2.05 2.15 2.42 2.55 2.55 3.45 3.67 5.27 5.87 15.52 1993 1.81 2.26 2.26 2.84 3.18 4.50 4.91 5.13 7.10 7.52 10.16 16.58 29.21 1992 2.30 3.18 3.18 3.24 4.11 5.17 5.97 6.06 6.98 7.16 9.13 10.62 20.43 1991 1.60 2.28 2.88 3.52 3.52 3.52 4.08 5.15 6.28 7.38 10.07 11.94 16.59 1990 1.82 2.35 2.37 2.37 2.37 2.37 2.37 2.37 2.90 2.90 3.33 6.23 17.33 1989 1.05 1.90 2.05 2.06 2.26 2.41 2.52 2.82 3.36 3.75 5.85 7.67 16.85 1988 1.55 1.90 1.90 1.90 1.90 1.90 2.05 2.13 2.75 3.47 4.78 6.57 11.67 1987 1.81 2.43 2.54 2.54 2.87 2.87 3.38 3.62 3.62 5.31 5.31 9.80 13.86 1986 2.75 4.85 5.65 6.65 6.85 6.95 7.90 8.00 8.00 9.45 12.97 18.47 33.02 1985 --- --- --- --- --- --- --- --- --- --- --- --- 17.93 1984 --- --- --- --- --- --- --- --- --- --- --- --- 23.39 1983 --- --- --- --- --- --- --- --- --- --- --- --- 41.81 1982 --- --- --- 4.62 5.24 5.24 5.53 5.53 7.29 8.43 9.95 15.59 39.56 1981 2.04 2.94 3.80 4.17 4.32 5.01 6.02 6.02 6.21 6.21 6.62 11.24 17.15 1980 --- --- --- --- --- --- --- --- --- --- --- --- 26.42 D
10/10/24, 2:23 PM Rainfall Depth Duration Frequency
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Section 13, Item J.
1979 1.54 2.28 2.83 3.82 3.82 3.82 4.02 4.97 5.49 6.53 7.09 12.65 20.87 1978 1.54 2.28 2.83 3.82 3.82 3.82 4.02 4.97 5.49 6.53 7.09 12.65 20.87 1977 0.92 1.03 1.09 1.12 1.12 1.12 1.24 1.26 1.26 1.26 2.18 3.32 8.73 1976 0.78 1.23 1.70 1.70 1.91 2.06 2.06 2.06 2.18 3.21 3.73 5.00 11.87 1975 1.97 2.56 3.14 3.27 3.38 3.52 4.84 6.08 7.82 8.47 8.50 15.06 28.24 1974 --- --- --- --- --- --- --- --- --- --- --- --- 33.80 1973 2.48 2.76 3.51 4.54 4.86 4.86 6.09 7.38 8.60 9.26 12.09 19.82 35.95 1972 3.05 3.88 3.92 3.98 3.98 5.03 5.90 5.96 6.05 6.73 7.92 9.62 16.80 1971 3.05 4.40 5.02 5.13 6.25 6.57 6.57 7.61 8.20 8.22 9.81 13.34 21.20 1970 2.94 2.94 3.48 3.48 3.72 3.72 4.97 5.90 6.37 7.01 9.55 12.27 21.13 1969 2.75 3.15 3.15 3.23 3.31 3.54 5.63 6.09 8.33 8.80 9.89 16.66 30.23 1968 1.76 2.12 2.12 2.43 2.43 2.48 2.51 3.20 3.20 3.49 4.61 8.77 17.12 1967 2.52 4.13 4.15 4.63 4.97 4.99 5.38 6.53 7.36 7.36 7.89 11.44 29.07 1966 1.79 1.95 2.46 2.48 3.27 3.74 4.03 4.13 5.17 5.17 5.17 9.69 16.47 1965 --- 3.43 --- --- --- --- --- 7.18 8.10 --- --- --- 25.01 1964 1.98 2.44 2.86 3.06 3.06 3.06 3.25 3.45 5.45 6.58 6.84 9.13 18.12 1963 2.88 3.52 4.20 4.65 4.65 4.65 4.65 4.65 6.07 6.38 6.38 10.35 24.44 1962 1.25 2.08 2.93 3.02 4.05 4.53 6.47 7.17 7.61 7.75 9.09 11.98 18.00 1961 1.38 1.68 2.16 2.16 2.16 2.26 2.40 2.77 2.93 3.23 4.81 6.51 13.82 1960 1.33 1.53 1.86 1.86 2.09 2.42 2.82 3.25 3.67 5.03 6.18 7.86 16.68 1959 1.65 2.09 2.09 2.55 2.88 3.22 3.68 4.01 4.01 4.75 6.13 10.54 13.45 1958 --- --- --- --- --- --- --- --- --- --- --- --- 41.69 1957 --- --- --- --- --- --- --- --- --- --- --- --- 18.93 1956 --- --- --- --- --- --- --- --- --- --- --- --- 28.58 1955 --- --- --- --- --- --- --- --- --- --- --- --- 18.28 1954 --- --- --- --- --- --- --- --- --- --- --- --- 16.40 1953 --- --- --- --- --- --- --- --- --- --- --- --- 15.10 1952 2.21 3.15 3.68 3.77 3.77 3.77 3.77 4.06 4.68 6.56 7.47 13.11 27.05 1951 4.65 5.30 5.30 5.30 5.55 5.70 6.24 6.25 6.25 8.87 10.85 14.60 28.76 1950 2.70 2.70 2.70 3.97 3.97 3.97 3.97 5.05 5.05 5.55 9.52 10.41 18.30 1949 1.76 2.71 3.14 3.14 3.14 3.14 3.72 3.86 4.87 5.45 6.93 10.49 17.23 1948 1.28 1.41 1.70 1.83 2.03 2.03 2.43 2.43 4.08 4.39 6.67 8.68 17.76 1947 2.16 3.12 3.20 3.20 3.91 3.91 3.91 4.13 4.13 4.13 4.82 7.33 14.54 1946 1.90 1.90 3.20 3.38 4.37 4.98 5.16 5.42 5.70 6.31 7.49 11.80 20.14 1945 2.68 3.88 4.78 4.78 4.98 5.27 5.27 5.27 5.66 5.66 5.66 9.58 23.66 1944 2.25 2.41 2.53 2.53 3.23 3.39 3.93 4.28 5.68 5.68 7.47 10.20 19.25 1943 2.05 2.78 3.58 3.81 4.43 4.77 5.38 5.42 7.10 8.03 10.13 15.90 27.61 1942 2.00 3.48 4.20 4.60 5.32 5.81 5.91 5.91 7.68 8.17 8.17 12.92 26.67 1941 1.85 2.40 2.46 3.46 5.46 5.46 4.17 4.52 7.17 8.59 11.13 14.00 25.17 1940 1.65 2.72 3.46 3.76 4.20 4.79 5.24 5.54 5.95 6.00 8.96 16.37 24.86 1939 1.72 2.40 2.55 2.80 2.80 2.80 2.80 2.80 2.80 3.17 3.42 5.93 14.01 1938 2.30 3.65 4.05 4.55 4.80 4.80 5.25 6.95 9.40 10.35 12.10 16.00 27.25 1937 4.40 4.65 5.85 6.15 6.60 6.95 7.70 8.15 8.70 9.50 10.10 19.90 34.99 1936 2.00 2.30 3.50 4.20 4.35 4.50 6.05 6.40 10.33 10.33 13.28 19.99 28.29 1935 2.50 2.72 2.72 2.72 3.25 4.30 4.52 4.52 5.22 5.65 6.35 9.47 23.94 1934 1.70 2.85 2.85 4.05 4.52 4.52 4.52 4.52 4.52 6.40 8.77 9.67 17.86 10/10/24, 2:23 PM Rainfall Depth Duration Frequency
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Section 13, Item J.
1933 1.20 1.72 1.72 1.72 2.32 3.12 3.12 3.82 3.82 3.82 5.07 7.87 12.77 1932 1.75 1.92 2.59 3.58 3.75 3.80 4.49 4.97 5.58 5.88 6.60 10.05 19.99 1931 1.65 1.65 1.65 2.53 2.53 2.53 2.65 2.65 2.65 2.65 3.92 6.39 12.62 1930 1.39 2.25 2.25 2.57 2.57 2.78 3.35 3.71 5.17 5.33 5.62 10.86 17.07 1929 1.91 2.98 3.49 3.49 3.49 3.49 3.49 3.57 4.07 4.07 4.07 6.57 15.52 1928 1.68 2.60 3.40 4.06 4.79 4.92 4.92 4.92 5.92 6.10 6.27 9.09 18.80 1927 1.50 3.00 3.00 4.25 4.25 4.51 5.46 5.96 6.26 6.91 7.41 10.51 24.11 1926 2.55 2.80 2.90 3.55 3.55 4.55 5.10 5.10 6.48 8.99 10.04 10.29 21.54 1925 1.95 3.05 3.27 3.27 3.52 3.74 4.27 5.79 5.94 7.79 8.41 11.84 28.60 1924 1.35 1.35 1.35 1.35 1.35 1.35 1.35 1.35 2.35 3.00 3.00 4.95 10.50 1923 2.20 3.00 4.30 5.30 5.30 5.30 5.50 6.10 6.70 6.70 9.30 14.15 26.07 1922 2.17 2.52 3.45 3.95 3.95 3.95 3.95 4.44 7.09 7.16 9.46 14.80 24.30 1921 3.85 3.95 4.50 4.72 4.72 4.72 4.72 5.72 6.62 7.02 7.72 13.51 26.57 1920 2.10 3.55 3.90 4.05 4.20 4.20 4.20 4.31 4.82 5.19 7.04 9.26 15.46 1919 2.25 3.55 3.90 4.00 4.05 4.40 4.60 4.70 5.00 6.45 8.15 10.35 18.75 1918 1.60 2.35 2.35 2.35 3.45 4.25 4.70 4.70 6.50 6.50 8.10 11.30 15.50 1917 1.30 2.30 2.60 2.90 3.25 3.55 4.10 4.35 4.55 4.55 5.35 7.25 17.70 1916 --- --- --- --- --- --- --- --- --- --- --- --- 20.00 1915 1.50 1.95 2.15 2.30 2.83 3.03 3.88 4.20 5.88 6.20 7.77 10.87 22.80 1914 2.26 3.11 3.49 3.61 3.99 3.99 3.99 4.48 5.47 6.96 9.81 13.52 22.90 1913 1.20 1.84 2.22 2.72 2.95 3.36 3.36 3.55 4.01 4.01 4.01 4.86 14.26 1912 0.69 1.04 1.15 1.22 1.30 1.45 1.86 2.16 2.47 2.86 3.43 5.36 12.68 1911 2.17 3.57 5.27 6.12 6.45 7.30 7.80 8.42 10.82 15.51 18.06 24.30 30.46 1910 2.00 3.00 3.00 3.45 3.88 3.88 3.93 3.93 4.00 4.69 5.92 8.90 20.89 1909 1.45 2.60 3.80 4.42 4.54 5.07 5.99 6.39 7.99 9.21 12.66 19.24 26.01 1908 1.30 1.60 1.60 1.78 1.78 1.78 1.83 3.03 3.63 3.63 5.51 9.04 14.27 1907 4.37 6.79 7.38 7.53 8.38 8.53 8.53 8.53 8.53 10.60 12.20 18.04 33.82 1906 2.40 2.54 3.22 3.62 3.85 3.85 3.85 5.03 7.47 9.20 10.45 15.43 30.93 1905 2.90 2.90 2.90 3.20 4.20 4.20 4.55 4.85 5.55 5.55 5.50 9.65 25.95 1904 1.51 2.62 3.12 3.15 3.15 3.25 3.75 4.86 6.07 6.42 7.20 12.05 21.42 1903 1.85 2.92 3.58 4.10 5.01 5.03 5.03 5.53 5.53 7.54 9.71 10.34 22.39 1902 1.21 1.79 2.09 2.61 3.01 3.41 3.87 4.41 5.03 6.03 7.72 9.29 20.19 1901 2.05 2.79 3.61 4.03 4.03 4.72 5.54 5.52 5.54 7.35 7.69 11.29 25.48 1900 1.85 2.34 2.41 2.80 2.86 2.86 2.86 3.88 4.82 5.66 6.45 9.69 21.51 1899 1.93 2.56 3.20 3.54 4.04 4.04 4.94 7.17 7.80 7.93 9.00 9.22 20.03 1898 3.60 4.47 4.64 4.64 4.64 4.64 4.64 4.76 5.11 5.11 5.23 7.30 13.77 1897 --- --- --- --- --- --- --- --- --- --- --- --- --- 1896 --- --- --- --- --- --- --- --- --- --- --- --- --- 1895 --- --- --- --- --- --- --- --- --- --- --- --- --- 1894 --- --- --- --- --- --- --- --- --- --- --- --- --- 1893 --- --- --- --- --- --- --- --- --- --- --- --- --- 1892 --- --- --- --- --- --- --- --- --- --- --- --- --- 1891 --- --- --- --- --- --- --- --- --- --- --- --- --- 1890 --- --- --- --- --- --- --- --- --- --- --- --- --- 1889 --- --- --- --- --- --- --- --- --- --- --- --- --- 1888 --- --- --- --- --- --- --- --- --- --- --- --- --- 10/10/24, 2:23 PM Rainfall Depth Duration Frequency
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California Irrigation Management Information System (CIMIS) Rendered in ENGLISH Units.Printed on Wednesday, August 31, 2022Average ETo Values by StationMonthly Average ETo Report Stn Id Stn Name CIMIS Region Jan
(in)
Feb
(in)
Mar
(in)
Apr
(in)
May
(in)
Jun
(in)
Jul
(in)
Aug
(in)
Sep
(in)
Oct(in)
Nov
(in)
Dec
(in)
Total
(in)
227 Plymouth SFH 1.48 1.95 3.02 4.57 5.97 7.19 7.64 6.98 4.99 3.24 1.68 1.21 49.92 CIMIS Region Abbreviations
BIS - Bishop CCV - Central Coast Valleys ICV - Imperial/Coachella Valley LAB - Los Angeles Basin MBY - Monterey Bay NCV - North Coast Valleys NEP - Northeast Plateau SAV - Sacramento Valley SBE - San Bernardino SFB - San Francisco Bay SJV - San Joaquin Valley SFH - Sierra Foothill SCV - South Coast Valleys

Section 13, Item J.

Castle Oaks Golf Course Recycled Water Demands TM
Attachment D
461
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1001 Galaxy Way
Suite 310
Concord CA 94520
925.949.5800 phone
925.949.5845 fax
westyost.com

TECHNICAL MEMORANDUM
DATE: December 10, 2024 Project No.: 988-50-24-10
SENT VIA: EMAIL
TO: George Lee, City of Ione
CC: Daniel Griffin, Castle Oaks Golf Course
Justin Granados, WaterStone Service
FROM: Allie Ahern, EIT
REVIEWED BY: Kathryn Gies, PE, RCE #65022
SUBJECT: Castle Oaks Golf Course Recycled Water Demands This technical memorandum (TM) provides information and supporting documentation related to water needs of the Castle Oaks Golf Course (golf course), which receives recycled water from the Castle Oaks Water Reclamation Facility (COWRF). The purpose of this TM is to inform development of a water balance for the Amador Regional Sanitation Authority (ARSA) wastewater disposal system. The following topics are addressed:
• Background Information
• Golf Course Irrigable Acreage
• Golf Course Storage Ponds
• Golf Course Agronomic Water Demands
• COWRF Influent Flows
• Golf Course Tailwater and Overspray Control and Monitoring

BACKGROUND INFORMATION
This section provides background information relevant to this TM. The following topics are addressed:
• Regulatory History
• Applicable Regulatory Standards for Water Balances
• Golf Course Demands vs. COWRF Influent Flows
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December 10, 2024

N-C-988-50-24-10 AS NEEDED-WP
Regulatory History
The City of Ione (City), ARSA and Portlock International Ltd. (Portlock) are the three entities permitted the Central Valley Water Quality Control Board (Regional Board) under Water Reclamation Requirement Order 93-240 (WRRs) to land apply recycled water from the COWRF to the golf course. The City owns and operates the COWRF, which provides the recycled water to the golf course. The City also owns the golf course, which is leased and operated by Portlock. ARSA is permitted to supply water to the COWRF to meet the irrigation needs of the golf course.

On August 14, 2024, the Regional Board issued a 13267 Order letter to the three WRRs permittees that requires the submission of an updated water balance for the ARSA system to the Regional Board by December 13, 2024. The letter specifies six items (A through F) that must be provided. This TM addresses the requirements under Item B of this letter, which states:

The acreage and agronomic rate at which recycled water can be applied to the Castle Oaks Golf Course without violating setback requirements, Title 22 requirements, impacting groundwater, or causing runoff to surface water. These numbers and calculations should be provided and certified by Ione and Portlock International LTD. Supporting documentation and references must be included in the submittal. Information regarding tailwater control/return and monitoring plans for compliance with applicable land application area requirements must also be included.

Applicable Regulatory Standards for Water Balances
The 13267 Order states that the water balance must be in compliance with the requirements and guidance of the Regional Board’s guidance document Requirements for Water Balance Update and Calibration, which is provided as Attachment A to the 13267 Order. Several of the procedures defined in this guidance document are applicable to the development of this TM, as follows:

Requirements for Water Balance Update and Calibration, Section 4:

The normal operations and maintenance of land application areas should be considered. [Operations and Maintenance] O&M Manuals should be referenced as well as historical monitoring data (i.e. percolation rates, observed standing water). Specific conditions of the [WRRs] should also be taken into account. The following should be taken into consideration:

A. Recycling area/land application area/disposal system hydraulic loading rates should be distributed monthly in accordance with expected seasonal variations based on crop evapotranspiration rates.

B. The distribution of precipitation (i.e. storm intensity, light rain over a lot of days or heavy rain over a few days), as well as other factors such as wind and saturated conditions must be taken into account when determining the number of days a disposal system can be operated each month. The most reliable way to estimate this is based off of historical records from a water year of intensity similar to that which is being modeled.

C. It should be specified whether the tailwater is collected, and if so if it is returned to the sprayfields directly or to one of the ponds.

D.If applicable, storm water runoff shall be accounted for in the tailwater return calculations.

E. Maximum disposal capacity of land application areas should be based on soil studies, cropping plans, percolation studies, and/or operator notes. 463
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December 10, 2024

N-C-988-50-24-10 AS NEEDED-WP
Requirements for Water Balance Update and Calibration, Section 5:

A. All water balances shall start on 1 October and end on 30 September. …
C. The water balance should include an assessment of the facility’s capacity and performance during a normal water year and during a year with a total annual precipitation for a return period of 100 years.

D. Local precipitation data for the 100-year annual return period, distributed monthly in accordance with mean monthly precipitation patterns shall be used. However, periods of high intensity storms should also be considered in the calculations.

E. All water balances should be based on all available data. All data should also be quality controlled and used with discretion.
…
G.For each wastewater treatment, storage, or disposal pond and containment structure, provide the following information:
a. Identification (name) and function of the pond.
b. Surface area, depth, and volumetric capacity at two feet of freeboard. c. Height (relative to surrounding grade), crest width, interior slope, and exterior slope of each berm or levee.
d. Materials used to construct each berm or levee.
e. Description of engineered liner, if any. Include a copy of the Construction Quality f. Estimated steady state percolation rate for each unlined pond. g. Depth to shallow groundwater below the base and pond inverts. h. Precipitation and evapotranspiration data shall be from recognized stations. The source of this information shall be provided, including a link to the data. i. Overfilling/overflow prevention features.
j. Operation and maintenance procedures.

Golf Course Demands vs. COWRF Influent Flows
During the COWRF tertiary treatment process, a fraction of the influent to the COWRF is discarded as filter backwash and sent to the City of Ione’s Wastewater Treatment Facility (WWTF). The remaining influent to the COWRF is treated to tertiary standards and recycled at the golf course. Therefore, the influent flow to the COWRF needs to be greater than the agronomic water demand of the golf course to accommodate the losses due to filter backwash, and the ARSA water balances need to include the portion of influent sent as filter backwash to the WWTF.

The City is concurrently in the process of preparing a water balance for its WWTF in accordance with a separate 13267 Order. The WWTF water balance will also need to account for the COWRF backwash flows.

Accordingly, this TM presents calculations that define both the COWRF influent flows needed to meet the golf course agronomic demands for use in the ARSA water balance and the backwash flow from the COWRF to the WWTF for use in the WWTF water balance.
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December 10, 2024

N-C-988-50-24-10 AS NEEDED-WP

GOLF COURSE IRRIGABLE ACREAGE
The irrigable acreage of the golf course was determined based on inspection of the golf course irrigation system and discussions with staff. This area was mapped and quantified using GIS mapping and data processing tools. Figure 1 presents the map created. The following areas of the golf course were not included in the calculated irrigable acreage:
• natural, undeveloped areas surrounding Mule Creek and Sutter Creek • areas abutting residences surrounding the golf course; some of these areas are irrigated by residents while others remain unirrigated
• hardscape and permanent water features
The total irrigable area of the golf course was determined to be 130 acres. 465
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December 10, 2024

N-C-988-50-24-10 AS NEEDED-WP

GOLF COURSE STORAGE PONDS
The golf course has nine ponds that can be filled with recycled water during the irrigation season. The ponds serve as aesthetic features and water hazard obstacles for the golf course and are used to hold recycled water before it is pumped to the golf course. Limited construction information is available for the ponds, but the ponds are understood to be unlined and constructed of native soil material. Estimates of the depth, volume and percolation rates of the ponds are not available. However, it is estimated that on average, the depth of groundwater below the golf course ranges from 8 to 13 feet. The surface area of each pond has been estimated using GIS mapping and data processing tools and is presented in Table 1.

Table 1. Golf Course Storage Pond Surface Area
Pond Name Surface Area, acres
Lake A 0.8
Lake B 1.2
Lake C 0.4
Lake D 1.1
Lake E 2.2
Lake F 1.1
Lake G 1.6
Lake H 1.4
Lake I 3.1
The ponds are hydraulically connected to each other. The maximum water level of each pond is controlled by a fixed standpipe located in an access port approximately 20 to 100 feet from the lake’s edge. Water overflowing the standpipe of the upstream lake is conveyed by to the following lake downstream, with Lake A being the furthest upstream lake, and Lake I being the furthest downstream lake. The Lake I overflow standpipe connects to a wetlands area that is tributary to the nearby surface water body Mule Creek. Figure 2 presents a schematic of the recycled water irrigation system.

Recycled water from the COWRF can be pumped directly to either Lake I or Lake A. Recycled water is then pumped from Lake I to the golf course irrigation system. Under current operations, recycled water is sent by default to Lake I. Golf course staff relate that recycled water is only pumped to Lake A for short periods during the irrigation season, when golf course demands are not keeping up with flows from the COWRF and Lake I is at risk of overflowing. Typically, recycled water that is directed to Lake A will remain in the Lake until it has percolated or evaporated. However, recycled water can discharge from Lake A to the downstream lakes if Lake A overflows. However, golf course staff indicate that the amount of recycled water flow sent to Lake A is not enough to result in overflows. 467
Section 13, Item J.

LEGEND
LAKES
B – H
City of Ione
Castle Oaks Golf Course
Project No.: 988-50-24-10 Recycled Water Demands
LAKE I

CASTLE OAKS
WATER

RECLAMATION

FACILITY
LAKE A

IRRIGATION

PUMP STATION

TO GOLF COURSE

PUTTING

GREEN &

DRIVING
RANGE

RECYCLED WATER

STORM/RECYCLED WATER

OVERFLOW TO

MULE CREEK

STORM WATER ONLY
Figure 2. Castle Oaks Golf Course Recycled Water
Storage and Irrigation System Schematic
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December 10, 2024

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The ponds also serve as catchment for stormwater runoff the golf course. During the winter rainfall season, stormwater runoff will fill the nine ponds, and they will eventually overflow to Mule Creek. To prevent the discharge of recycled water to Mule Creek, recycled water is only delivered to the golf course during the irrigation season (typically between April and October). This allows for water in Lake I to percolate and evaporate before the rainy season begins. In addition, the recycled water remaining in Lake I at the end of the irrigation season is diluted with 1.2 million gallons of potable water. Golf course staff reported that this practice was developed in partnership with the California Department of Health Services1 to minimize the potential for discharge of recycled water to surface waters.

GOLF COURSE AGRONOMIC WATER DEMANDS
Calculation Procedures
The steps and major assumptions used to determine the rate at which recycled water can be supplied to the golf course are described below.

Climate Data
Rainfall data reported by the Ione National Climate Data Center (NCDC) weather station #0442832 was used to define the average annual rainfall, 1-in-100-year annual rainfall, and the monthly distributions of rainfall, as follows:
• The average rainfall year was defined as having a total rainfall of 22.0 inches. • The 1-in-100 rainfall year was defined as having a total rainfall of 41.1 inches. • The monthly distributions were defined based on the 1906 to 1977 monthly Normal rainfall distribution values, with the Normal values being statistically determined values reported by the California Department of Water Resources (DWR).

DWR defined all of these values. This information on is documented in Attachment A and summarized in Table 2.

Reference evapotranspiration (ET) for each month is based on long-term monthly average ET values for the Plymouth California Irrigation Management Information System (CIMIS) Station #227, located approximately 13 miles northeast of the golf course. This information is documented in Attachment A of this TM and summarized in Table 2, along with the monthly total rainfall values for the average and 1-in-100 rainfall years.
1 CDPH has since been incororpated into the State Water Board as the Division of Drinking Water (DDW). 469
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December 10, 2024

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Table 2. Applicable Climate Data
Month Average Rainfall,
(a) inches 1-in-100 Year Rainfall,(a) inches Reference ET,(b) inches October 1.15 2.15 3.24
November 2.81 5.24 1.68
December 3.54 6.58 1.21
January 5.09 9.48 1.48
February 3.14 5.86 1.95
March 3.20 5.95 3.02
April 1.75 3.26 4.57
May 0.63 1.18 5.97
June 0.23 0.43 7.19
July 0.07 0.13 7.64
August 0.13 0.24 6.98
September 0.33 0.62 4.99
Total 22.1 41.1 49.9
(a) NCDC weather station #044283
(b) Plymouth CIMIS station #227
Crop ET
Monthly crop ET values for the golf course were calculated by multiplying the reference ET values from Table 2 by a representative crop coefficient. Grasses grown on the golf course include:
• perennial rye grass
• poa annua
• creeping bent grass
• tall fescue
• Bermuda grass
Apart from Bermuda grass, all grasses used on the golf course are considered cool season grasses. Meyer and Gibeault at the University of California, Irvine report monthly crop coefficients for cool season grasses (see of Attachment B). The average of these reported monthly crop coefficients for April to October, calculated to be 0.88, was used as a representative crop coefficient for all months.

Pond ET
Monthly ET values for the storage pond Lake I were set equal to the respective monthly reference ET values. 470
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December 10, 2024

N-C-988-50-24-10 AS NEEDED-WP
Historical Recycled Water Demands
Evaluation of historical recycled water demands was based on the following:
• To properly maintain the golf course greens, recycled water is delivered to the COWRF and golf course solely based on golf course demands.
• Golf course flow data is tracked by golf course staff, and total monthly and annual flow volumes based on this data are shown in Table 3.
• The historical average volume of recycled water delivered was calculated for each calendar month and was used to calibrate and confirm the theoretical recycled water demand for the golf course.

Table 3. Historical Golf Course Recycled Water Demand
Month
Volume of Recycled Water Used, million gallons (MG) Average, 2017 2018 2019 2020 2021 2022 2023 2024 Average acre-feet October 16.5 8.4 16.7 14.5 8.2 9.1 11.9 20.3(a) 12.2 37.4 November 0 3.2 13.9 6.1 0 9.1 0 2.6(a) 5.3 16.4
December 0 0 0 0 0 0 0 0 0 0
January 0 0 0 0 0 0 0 0 0 0
February 0 0 0 0 0 0 0 0 0 0
March 0 0 0 0 0 0 0 0 0 0
April 0 0 0 1.1 12.7 8.1 0.9 0 2.9 8.8
May 18.1 19.1 15.1 14.1 25.2 12.1(b) 15.8 17.6 17.9 54.9 June 25.6 26.5 21.1 19.6 21.4 10.8(b) 22.0 28.3 23.5 72.2 July 29.4 29.0 27.2 26.6 31.7 20.4 25.1 28.3 27.2 83.6
August 29.1 29.8 26.5 25.8 23.3 21.0 22.0 26.1 25.5 78.1 September 23.0 24.1 24.1 16.2 9.0(c) 15.7 15.0 24.2 20.3 62.4 Total, MG 141.7 140.2 144.6 123.9 131.5 106.3 118.1 147.5 134.8 413.8 (a) Values excluded from average calculation. The COWRF influent flow meter failed on October 9, 2024 and COWRF staff requested that water be sent to the COWRF at a steady rate of 800 gallons per minute until the end of the irrigation season in mid-November.

Therefore, during this period, there was less ability to match the effluent flows from the COWRF to golf course agronomic demands and it is not clear these are representative values.
(b) Values excluded from average calculation. There was limited recycled water supply available from ARSA during the period of May to June 2022 and the golf course was under-irrigated.
(b) Value is excluded from average because it is anomalous when compared with September recycled water use volumes of other years.

Operations staff responsible for this data are not available to confirm its accuracy.

Theoretical Recycled Water Demands
Theoretical recycled water demands for the golf course were developed based on the following:
• Theoretical agronomic demands are calculated by multiplying the difference between the calculated monthly crop ET and monthly rainfall values by the total area of the golf course (130 acres) and dividing by an irrigation efficiency factor. For months with more precipitation than ET, the irrigation demand was set equal to zero.
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• Irrigation efficiencies for solid set spray irrigation systems like that used on the golf course can range from 60 to 85 percent (see Attachment C, Table 8.2b). A calibration process, described in the next section, has been used to define the irrigation efficiency for this site. • Theoretical evaporative losses from the storage ponds are calculated by multiplying the difference between the reference ET and monthly rainfall values by the total area of the impoundment. • As noted previously, recycled water is only sent to and pumped from Lake I. Therefore, evaporative losses from only Lake I (3.1 acres) are included. • Losses are calculated for months only when recycled water is delivered to the golf course. • There have been no attempts to quantify percolation losses from Lake I. Therefore, percolation losses are assumed to be zero.
• Total theoretical recycled water demands are the sum of the theoretical monthly golf course agronomic demands and the theoretical monthly evaporative losses from Lake I.

Average Year Theoretical Recycled Water Demand Calibration The site-specific irrigation efficiency factor used to calculate the theoretical irrigation demand is determined by adjusting the irrigation efficiency value used in the calculation of the average-year theoretical recycled water demand until the demand matches the historical recycled water supplied.

The resulting irrigation efficiency is 84 percent, on the upper end of the typical range for spray irrigation cited above. This calibration process demonstrates that the golf course irrigation system is very efficient and experiences limited losses.
1-in-100 Year Recycled Water Demand
The 100-year theoretical recycled water demand is calculated using the procedures described above but applying 1-in-100-year rainfall values and retaining the 84 percent irrigation efficiency determined from the average year water balance.

Agronomic Water Demands
The calculated average rainfall year theoretical demand to be used in the water balance analysis is shown in Table 4. The calculated average 1-in-100-year theoretical demand to be used in the water balance analysis is shown in Table 5.

The historical data show irrigation demands in November, but the theoretical demands do not indicate a need for irrigation water in this month. This discrepancy likely reflects the fact that rainfall typically does not begin until late November in this area, while there are still irrigation demands earlier in the month.

Despite this discrepancy, the annual theorical demand matches closely to the historical values for the average year. Therefore, the methodology applied provides an accurate estimate for purposes of developing an annual water balance for COWRF.
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Table 4. Monthly Golf Course Recycled Water Demand for an Average Rainfall Year Month
(1) (2) (3) (4) (5) (6)
Climate Values, inches Historical
Demand,
acre-feet
Theoretical Average-Year Demand, acre-feet
Rainfall
Reference
ET
Irrigation
Demand
Pond
Losses
Total
Demand
October 1.15 3.24 37.4 21.9 0.5 22.4
November 2.81 1.68 16.4 0 0 0
December 3.54 1.21 0 0 0 0
January 5.09 1.48 0 0 0 0
February 3.14 1.95 0 0 0 0
March 3.20 3.02 0 0 0 0
April 1.75 4.57 8.8 29.3 0.7 30.0
May 0.63 5.97 54.9 59.6 1.4 61.0
June 0.23 7.19 72.2 78.6 1.8 80.4
July 0.07 7.64 83.6 85.8 2.0 87.8
August 0.13 6.98 78.1 77.5 1.8 79.3
September 0.33 4.99 62.4 52.4 1.2 53.6
Total, acre-feet
per year (AFY) 22.0 49.9 413.8 405.1 9.4 414.5
Notes:
(1) 1906-1977 monthly rainfall normals for Ione NCDC weather station #044283 (2) Long-term monthly average reference ET from Plymouth CIMIS station #227 (3) Average of monthly irrigation volumes applied to the golf course from 2017 to 2024 from Table 3 (4) = (irrigated area of 130 acres) x [Column 2 x (crop coefficient of 0.88) - Column 1] / (irrigation efficiency of 0.84) / 12 inches/foot (5) = (storage pond area of 3.1 acres) x (Column 2 - Column 1) / 12 inches per foot (6) = Column 4 + Column 5
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December 10, 2024

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Table 5. Monthly Golf Course Recycled Water Demand for a 1-in-100 Rainfall Year Month
(1) (2) (3) (4) (5)
Climate Values, inches Theoretical 100-Year Demand, acre-feet Rainfall Reference ET Irrigation Demand Pond Losses Total Demand October 2.15 3.24 9.0 0.3 9.3
November 5.24 1.68 0 0 0
December 6.58 1.21 0 0 0
January 9.48 1.48 0 0 0
February 5.86 1.95 0 0 0
March 5.95 3.02 0 0 0
April 3.26 4.57 9.8 0.3 10.1
May 1.18 5.97 52.5 1.2 53.7
June 0.43 7.19 76.1 1.7 77.8
July 0.13 7.64 85.0 1.9 86.9
August 0.24 6.98 76.1 1.7 77.8
September 0.62 4.99 48.6 1.1 49.7
Total, AFY 41.1 49.9 357.1 8.2 365.3
Notes:
(1) = 100-year return period annual total distributed monthly in proportion to 1906-1997 monthly Normals for Ione NCDC weather station #044283
(2) Long-term monthly average reference ET from Plymouth CIMIS station #227 (3) = (irrigated area of 130 acres) x [Column 2 x (crop coefficient of 0.88) - Column 1] / (irrigation efficiency of 0.84) / 12 inches per foot (4) = (storage pond area of 3.1 acres) x (Column 2 - Column 1) / 12 inches/foot (5) = Column 4 + Column 5
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December 10, 2024

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COWRF INFLUENT FLOWS
Calculation Procedures
The theoretical influent flow to the COWRF is calculated for each month using the following formula:

Golf Course Irrigation Demand/(1-backwash percentage)
The Golf Course Irrigation Demands were discussed in the previous section. The backwash percentages are calculated based on historical COWRF influent and backwash flow data, as described in the sections below.

Historical COWRF Influent Flows
Historical monthly influent flows to the COWRF are shown in Table 6. Influent flows beginning in April 2022 are reported in the monthly COWRF discharge monitoring reports (DMRs). Prior to 2022, COWRF DMRs did not present influent flows. However, the influent flows were determined from available golf course demand data and backwash flow data.2
Table 6. Historical COWRF Influent Flows
Month
Volume of COWRF Influent Flow, MG
2017 2018 2019 2020 2021 2022 2023 2024 Average
October 19.5 10.3 20.7 17.9 10.5 10.9 19.2 27.7(a) 17.1 November 0 4.8 15.8 7.8 0 11.3 9.3 4.0(a) 8.8
December 0 0 0 0 0 0 0 0 0
January 0 0 0 0 0 0 0 0 0
February 0 0 0 0 0 0 0 0 0
March 0 0 0 0 0 2.0 0 0 2.0
April 0 0 0 0.9 14.4 12.7 2.1 0 7.5
May 20.4 21.6 17.1 16.8 29.1 14.0(b) 18.8 19.8 19.7
June 29.1 30.1 23.7 23.0 24.7 13.1(b) 25.8 32.0 25.2
July 34.1 33.5 31.2 30.2 35.7 23.1 29.5 32.1 31.2
August 33.3 36.9 33.3 30.1 27.0 23.2 27.4 32.3 30.3
September 27.1 27.7 28.1 20.2 11.2(b) 18.5 21.4 28.0 22.8 Total, MG 163.4 164.9 169.7 146.7 152.7 128.8 153.5 174.7 164.5 (a) Values excluded from this evaluation. The COWRF influent flow meter failed on October 9, 2024. Reported influent is an estimate of the actual flow received during this period.
(b) Although values reported in these months are not representative of typical influent flows (and thus irrigation demands), they are useful in determining the percentage of backwash flow generated. Therefore, these values are not excluded from this portion of the analysis. 2 To determine influent flows prior to April 2022, monthly COWRF effluent flows from the DMRs were compared to golf course flows and filter backwash flows. If the reported COWRF effluent flow was larger than the golf course flow, it was confirmed to be actual influent flow by verifying that it was equal to the sum of the golf course influent flow and the filter backwash flow. If the reported COWRF effluent flow was equivalent to the golf course flow, the COWRF influent flow was calculated by summing the COWRF effluent flow and filter backwash flow. The 2017 COWRF influent flows were calculated by summing monthly golf course influent flows and filter backwash flows because COWRF DMRs were not available. 475
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December 10, 2024

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Historical COWRF Backwash Flows
Historical monthly filter backwash flows from the COWRF are shown in Table 7 .

Table 7. Historical COWRF Filter Backwash Flows
Month
Volume of COWRF Filter Backwash Flow, MG
2017 2018 2019 2020 2021 2022 2023 2024 Average
October 3.0 1.9 4.0 3.4 2.4 1.7 7.3(a) 5.0 3.1
November 0 1.1 1.9 1.7 0 2.3 4.1(a) 1.7 1.2
December 0 0 0 0 0 0 0 0 0.0
January 0 0 0 0 0 0 0 0 0.0
February 0 0 0 0 0 0 0 0 0.0
March 0 0 0 0 0 0 0 0 0.0
April 0 0 0 0 2.0 2.0 0.1 0 1.4
May 2.2 2.5 1.9 2.7 3.9 1.9 3.0 2.2 2.5
June 3.4 3.6 2.5 3.8 3.4 2.0 3.7 3.6 3.2
July 4.7 4.4 3.9 3.6 4.0 2.7 4.4 3.8 3.9
August 4.2 3.9 3.9 4.3 3.8 2.7 5.4(a) 5.1 4.0
September 4.1 3.5 4.0 4.0 2.6 2.2 6.4
(a) 5.5 3.7
Total, MG 21.7 20.9 22.1 23.4 21.9 17.5 34.4 26.8 23.5
(a) Values were not used in calculated average. Operations staff were performing excessive backwashing of the filters. This practice has since ceased.

Filter Backwash Flow Percentages
The percentage of COWRF influent flow that was discarded as backwash flow to the WWTF each month was calculated by dividing the backwash flow by the influent flow. Table 8 shows the results of this calculation. From the percentages shown, a monthly average was calculated. Monthly average backwash percentages range from 13 to 20 percent.
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December 10, 2024

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Table 8. Historical COWRF Filter Backwash Flow Percentage Month
Filter Backwash Flow as a Percentage of Influent Flow, percent 2017 2018 2019 2020 2021 2022 2023 2024 Average
October 15 18 19 19 23 16 38
(a) 18(b) 18
November -
(c) 23 12 22 - 20 44(a) 41(b) 19
December - - - - - - - - -
January - - - - - - - - -
February - - - - - - - - -
March - - - - - - - - -
April - - - - 14 16 7
(d)
- 15
May 11 12 11 16 13 13 16 11 13
June 12 12 11 16 14 15 15 11 13
July 14 13 13 12 11 12 15 12 13
August 13 11 12 14 14 12 20(a) 16 13
September 15 13 14 20 23 12 30(a) 20 17
(a) Values were not used in calculated average. Operations staff were performing excessive backwashing of the filters. This practice has since ceased.
(b) Values excluded from this evaluation. The COWRF influent flow meter failed on October 9, 2024. Reported influent is an estimate of the actual flow received during this period. (c) “-“ indicate there were no flows to the COWRF during this period. (d) The backwash percentage during April 2023 was abnormally low. Influent flow to the COWRF began six days before the end of the month and effluent and backwash were only discharged on two of the six days. This value was not used in the calculated average.
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December 10, 2024

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Theoretical COWRF Influent Flow
The calculated average rainfall year theoretical flow to the COWRF to be used in the water balance analysis is shown in Table 9. The calculated average 1-in-100-year theoretical flow to the COWRF to be used in the water balance analysis is shown in Table 10.

Table 9. Monthly COWRF Influent Demand for an Average Rainfall Year Month
Average-Year Golf Course
Recycled Water Demand,
(a)
acre-feet
COWRF Backwash Flow as a
Percentage of Influent Flow,
(b)
percent
Average-Year
COWRF Influent Flow,
(c)
acre-feet
October 22.4 18 27.3
November 0 19 0
December 0 - 0
January 0 - 0
February 0 - 0
March 0 - 0
April 30.0 15 35.3
May 61.0 13 70.1
June 80.4 13 92.4
July 87.8 13 100.9
August 79.3 13 91.1
September 53.6 17 64.6
Total, AFY 414.5 - 481.7
(a) From Table 4, Column 6
(b) From Average column in Table 8
(c) = Column 1/(1 - Column 2)
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Table 10. Monthly COWRF Influent Capacity for a 1-in-100 Rainfall Year Month
1-in-100-Year Golf Course
Recycled Water Demand,
(a)
acre-feet
COWRF Backwash Flow as a
Percentage of Influent Flow,
(b)
percent
1-in-100-Year
COWRF Influent Flow,
(c)
acre-feet
October 9.3 18 11.3
November 0 19 0
December 0 - 0
January 0 - 0
February 0 - 0
March 0 - 0
April 10.1 15 11.9
May 53.7 13 61.7
June 77.8 13 89.4
July 86.9 13 99.9
August 77.8 13 89.4
September 49.7 17 59.9
Total, AFY 365.3 - 423.5
(a) From Table 5, Column 5
(b) From Average column in Table 8
(c) = Column 1 / (1 - Column 2)
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Theoretical COWRF Backwash Percentages and Flows
A calculated theoretical backwash flow from the COWRF to the WWTF will be used in the water balance analysis for the WWTF, based on the influent flows from Table 9 and Table 10 and average historical backwash flow percentages by month from Table 8. The theoretical COWRF backwash flow for an average rainfall year is shown in Table 11. The theoretical COWRF backwash flow for a 1-in-100 rainfall year is shown in Table 12.

Table 11. Monthly COWRF Backwash Flow for an Average Rainfall Year Month
Average-Year
COWRF Influent Flow,
(a)
acre-feet
COWRF Backwash Flow as a
Percentage of Influent Flow,
(b)
percent
Average-Year
COWRF Backwash to WWTF,
(c)
acre-feet
October 27.3 18 4.9
November 0 19 0
December 0 - 0
January 0 - 0
February 0 - 0
March 0 - 0
April 35.3 15 5.3
May 70.1 13 9.1
June 92.4 13 12.0
July 100.9 13 13.1
August 91.1 13 11.8
September 64.6 17 11.0
Total, AFY 481.7 - 67.2
(a) From Table 9
(b) From Table 8
(c) = Column 1 x Column 2
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Table 12. Monthly COWRF Backwash Flow for a 1-in-100 Rainfall Year Month
1-in-100-Year
COWRF Influent Flow,
(a)
acre-feet
COWRF Backwash Flow as a
Percentage of Influent Flow,
(b)
percent
1-in-100-Year
COWRF Backwash to WWTF,
(c)
acre-feet
October 11.3 18 2.0
November 0 19 0
December 0 - 0
January 0 - 0
February 0 - 0
March 0 - 0
April 11.9 15 1.8
May 61.7 13 8.0
June 89.4 13 11.6
July 99.9 13 13.0
August 89.4 13 11.6
September 59.9 17 10.2
Total, AFY 423.5 - 58.2
(a) From Table 10
(b) From Table 8
(c) = Column 1 x Column 2

GOLF COURSE TAILWATER AND OVERSPRAY CONTROL AND MONITORING This section provides information about Best Management Practices (BMPs) and monitoring for tailwater and overspray control from the golf course. The following topics are addressed:
• Golf Course Field Monitoring
• Golf Course Best Management Practices
• Golf Course Storage Pond Monitoring
Golf Course Field Monitoring
The City, in coordination with the golf course management, is required to perform daily, weekly, and monthly monitoring of the golf course when recycled water is being applied, as outlined in the WRR’s Monitoring and Reporting Program (MRP). These requirements are summarized in Table 13. In addition to the elements outlined below, the daily inspections must note any evidence of erosion, field saturation, runoff or the presence of nuisance conditions.

The MRP was adopted December 21, 2021, and did not become effective until after the end of the 2021 irrigation season. Since its adoption, the MRP requirements related to the golf course operations shown in Table 13 have not been satisfied. The City and golf course staff are currently developing the protocols to implement this monitoring and will initiate the program beginning in the 2025 irrigation season. 481
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December 10, 2024

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Table 13. Golf Course Monitoring Requirements
Constituent Units Type of Sample Sampling Frequency Reporting Frequency Flow gallons Continuous
Daily Monthly
Rainfall(a) inches Measurement
Acreage Applied(b) acres Calculated
Tailwater Runoff Observation -- Observation
(a) As measured at the weather station nearest to the disposal site. (b) Specific disposal fields shall be identified.

Flow
Currently, golf course staff monitor the daily total flow that is applied to the golf course. This flow is measured from the irrigation pump station and recorded in the golf course’s central computer system.

The measurement can be reported in up to 15-minute increments. Golf course staff report the daily total flows to the City.

Rainfall
Rainfall collects in a plastic rain gage located at the maintenance yard, and golf course staff manually read the gage daily at approximately the same time of day. That measurement is compared to a reported weather station located in the nearby City of Jackson to confirm its accuracy. The onsite, measured rainfall data is reported to the City.

Acreage Applied
The golf course’s central computer system has the ability report the areas that are watered each night.

These areas are grouped and reported by area category according to the type of plant that is watered.

The area categories are:
• Greens
• Tees
• Fairway
• Perimeter
• Rough
• Club House
• Driving Range
• Putting Green
Irrigation generally occurs on all areas of the golf course simultaneously. In rare instances an area category may be watered alone. Starting with the 2025 irrigation season, golf course staff will report the acreage that is watered daily and include that information in the flow report provided to the City monthly. 482
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December 10, 2024

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Tailwater Runoff Observation Monitoring
Starting with the 2025 irrigation season, City staff will inspect the golf course daily for evidence of runoff and overspray. These inspections will occur in the morning, just after irrigation occurs. During these inspections, special attention will be paid to the following five vulnerable areas, which have the most potential for recycled water to escape the use area:
• Castle Oaks Clubhouse
• Areas abutting Mule Creek
• Spyglass Drive near the Irrigation Pump Station
• Castle Oaks Drive and Shakeley Lane intersection
• Near the bathroom by Vista Lane
Monitoring each location will be done through an observatory drive by each location in the early morning.

Evidence of runoff or overspray includes wet areas on hardscape sidewalks and roadways surrounding the extents of the landscaped area. If these areas are wet or water appears to be draining from landscape into the gutters, the irrigation system should be further investigated for problems. Inspection logbook entries for the golf course monitoring will be submitted with the monthly monitoring reports.

Golf Course Best Management Practices
Overspray and runoff of recycled water from the use area is minimized and controlled through the implementation of BMPs. Spray irrigation systems are vulnerable to inefficiencies related to runoff or overspray caused by pressure fluctuations, wind, or equipment malfunction. If any part of the system is not working optimally, the result is a less uniform application of water which increases the likelihood of water escaping the recycled water use area. Even the most efficiently designed system must be maintained and constantly monitored to mitigate system avoid problems.

The COWRF BMP strategies include engineered controls and mechanisms to minimize runoff or overspray and practices to improve the application of water to a use area. Specific BMPs employed to control for runoff or overspray include:
• Irrigation is ceased during extended and extensive windy periods. • Irrigation is avoided when the soil is saturated to prevent runoff. • All sprinkler heads are uniform in brand, model and nozzle size to apply water as uniformly across the plant material as possible.
• A minimum four-foot distance from neighboring backyards and buildings is maintained as practical throughout areas of the golf course. This has been done through head removal, spray range or arc reduction or elimination of a zone. In areas where the four-foot buffer cannot be maintained and irrigated turf is desired, such as near a tee, hole or walkways, the irrigation water is applied with lower impact heads with a smaller arc radius. • Irrigation occurs in the evening or early morning hours to avoid public interaction, reduce evaporative loses, and take advantage of calmer wind patterns. • Good horticultural practices are performed including, mowing, de-thatching, aeration, and pest control as necessary to increase the plant and soil water absorbance. • Irrigation is applied as close as practical to match the amount of water lost through ET and the soil needs.
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• Duration of water application is applied to match percolation rates to reduce runoff. • Installation of low angle heads have been installed in areas near residential backyards to reduce mist from wind drift of spray.
• Tall plants are present along edges and perimeters to create a plant buffer. • Regular maintenance is performed of the irrigation system which includes inspecting and repairing leaks.

Golf Course Storage Pond Monitoring
Monitoring of irrigation storage ponds when they contain recycled water is also required under the MRP.

These requirements are summarized in Table 14.

Table 14. Golf Course Storage Pond Monitoring Requirements Constituent Units Type of Sample Sampling Frequency Reporting Frequency Freeboard feet Measurement Twice Weekly –
3 days apart
Monthly
Odors -- Observation Weekly
Dissolved Oxygen milligrams per
liter Grab Weekly
pH pH units Grab Monthly
Similar to the irrigation area, the MRP requirements related to the ponds have not been consistently satisfied. The City and golf course staff are currently developing the protocols to implement this monitoring and will initiate the program beginning in the 2025 irrigation season.

Freeboard
The MRP requires the freeboard be monitored as the difference between the top of the bank of the storage pond to the level of the water. This measurement provides the City with confidence that recycled water cannot escape the storage pond containment area. However, as noted previously, each pond is equipped with a standpipe that serves as an overflow structure. Therefore, it is more appropriate to monitor freeboard as the difference between the top of the overflow structure to the top of the water surface.

Currently, the City has the ability to measure the freeboard of Lake A by means of a level monitoring rod.

This capability is not set up in Lakes B through I. Lake I is manually kept at a level that is below the 12-inch overflow standpipe that conveys overflow water to a wetland area that eventually flows to Mule Creek.

Prior to the start of the 2025 irrigation season, the City will need to install a level monitoring rod in each pond so that freeboard can be measured.

In addition, the City will employ the following monitoring practices in the 2025 irrigation season:
• Twice a week during the irrigation season, each storage pond should be observed, and freeboard monitored.
• For Pond I, it is expected that there will be recycled water present in the pond throughout the irrigation season and this pond should be monitored during each bi-weekly event. 484
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• Recycled water is occasionally directed to Pond A. Therefore, this pond will be inspected as part of the bi-weekly monitoring. If there is standing water present in Pond A, then monitoring of this pond will be completed.
• If there is any evidence that Pond A has overflowed to Pond B (or any downstream pond) via the pond standpipes, then monitoring of the downstream ponds will also be performed. • City staff will be responsible for making the appropriate observations to determine whether recycled water is being stored in any of the ponds.
• Golf course staff will provide information to the City regarding where COWRF flows are directed.

Specifically, the monthly reports provided to the City will include information about which pond was receiving flow on each day.

Odors
The City is required to evaluate if any objectionable odors are being emitted from the storage ponds once every week. This will be needed for each pond that holds recycled water.

Dissolved Oxygen and pH
The City is required to collect and measure the dissolved oxygen and pH in a grab sample collected from each recycled water storage pond weekly. These measurements can be made using field test instruments provided that:
• The operator is trained in proper use and maintenance of the instruments, • The instruments are field calibrated at the frequency recommended by the manufacturer, • The instruments are serviced and/or calibrated at the manufacturer’s recommended frequency, and • Field calibration reports are maintained and a calibration log verifying calibration of all handheld monitoring instruments and devices are submitted with the monthly monitoring report. 485
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Rainfall and Reference ET Data
Attachment A
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IONE, CALIFORNIA (044283)
Period of Record Monthly Climate Summary
Period of Record : 03/01/1906 to 06/30/1977
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Average Max.

Temperature (F) Insuff icient Data
Average Min.

Temperature (F) Insuff icient Data
Average Total
Precipitation (in.) 5.08 3.14 3.19 1.75 0.63 0.23 0.07 0.13 0.33 1.15 2.81 3.53 22.04 Average Total
SnowFall (in.) 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 Average Snow Depth
(in.) 0 0 0 0 0 0 0 0 0 0 0 0 0
Percent of possible observations for period of record.

Max. Temp.: 0% Min. Temp.: 0% Precipitation: 99.9% Snowfall: 99.9% Snow Depth: 99.8% Check Station Metadata or Metadata graphics for more detail about data completeness.

Western Regional Climate Center, [email protected]
10/10/24, 2:42 PM IONE, CALIFORNIA Period of Record Monthly Climate Summary https://wrcc.dri.edu/cgi-bin/cliRECtM.pl?ca4283 1/1
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Rainfall Depth Duration Frequency at Ione
Station Number Station County Latitude Longitude Elevation Years Recorded B00 4283 00 Ione Amador 38.348 -120.938 284.0 89
Rainfall Statistics 1-Day 2-Day 3-Day 4-Day 5-Day 6-Day 8-Day 10-Day 15-Day 20-Day 30-Day 60-Day 1-Year Pr=0.5 1.92 2.55 3.01 3.38 3.70 3.99 4.48 4.91 5.79 6.51 7.68 10.19 21.28 Pr=0.2 2.55 3.37 3.98 4.47 4.89 5.27 5.92 6.48 7.64 8.58 10.11 13.39 27.84 Pr=0.1 2.92 3.87 4.55 5.11 5.60 6.02 6.76 7.40 8.71 9.78 11.52 15.23 31.54 Pr=0.04 3.36 4.44 5.22 5.86 6.40 6.89 7.73 8.45 9.94 11.16 13.13 17.32 35.70 Pr=0.02 3.66 4.83 5.67 6.36 6.96 7.48 8.39 9.17 10.78 12.09 14.22 18.74 38.51 Pr=0.01 3.94 5.19 6.10 6.84 7.47 8.04 9.01 9.84 11.57 12.97 15.23 20.06 41.11 Pr=0.005 4.21 5.54 6.51 7.29 7.96 8.56 9.59 10.48 12.31 13.79 16.19 21.31 43.57 Pr=0.002 4.54 5.97 7.01 7.85 8.58 9.22 10.33 11.28 13.23 14.82 17.40 22.87 46.64 Pr=0.001 4.79 6.29 7.38 8.26 9.02 9.69 10.85 11.85 13.90 15.57 18.26 23.99 48.84 Pr=0.0001 5.53 7.26 8.50 9.52 10.39 11.15 12.48 13.62 15.96 17.87 20.94 27.46 55.66 Annual Maxima 1-Day 2-Day 3-Day 4-Day 5-Day 6-Day 8-Day 10-Day 15-Day 20-Day 30-Day 60-Day 1-Year 2007 --- --- --- --- --- --- --- --- --- --- --- --- --- 2006 --- --- --- --- --- --- --- --- --- --- --- --- --- 2005 --- --- --- --- --- --- --- --- --- --- --- --- --- 2004 --- --- --- --- --- --- --- --- --- --- --- --- --- 2003 --- --- --- --- --- --- --- --- --- --- --- --- --- 2002 --- --- --- --- --- --- --- --- --- --- --- --- --- 2001 --- --- --- --- --- --- --- --- --- --- --- --- --- 2000 1.85 2.80 4.29 4.74 4.99 4.99 5.22 5.79 7.52 9.05 10.35 11.82 21.39 1999 2.02 2.44 3.42 3.42 3.42 3.42 3.42 4.17 5.51 5.72 8.41 10.90 15.39 1998 2.37 3.55 4.11 4.36 4.98 5.85 6.61 7.31 8.07 10.05 14.21 21.25 30.46 1997 2.37 3.55 4.11 4.36 4.98 5.85 6.61 7.31 8.07 10.05 14.21 21.25 43.59 1996 3.75 3.85 3.85 3.85 3.85 3.85 3.85 3.85 4.74 5.27 6.16 11.53 22.80 1995 2.90 4.71 5.05 5.33 5.58 5.71 7.45 8.02 9.08 9.83 12.42 16.90 35.50 1994 1.27 1.70 1.95 2.05 2.15 2.42 2.55 2.55 3.45 3.67 5.27 5.87 15.52 1993 1.81 2.26 2.26 2.84 3.18 4.50 4.91 5.13 7.10 7.52 10.16 16.58 29.21 1992 2.30 3.18 3.18 3.24 4.11 5.17 5.97 6.06 6.98 7.16 9.13 10.62 20.43 1991 1.60 2.28 2.88 3.52 3.52 3.52 4.08 5.15 6.28 7.38 10.07 11.94 16.59 1990 1.82 2.35 2.37 2.37 2.37 2.37 2.37 2.37 2.90 2.90 3.33 6.23 17.33 1989 1.05 1.90 2.05 2.06 2.26 2.41 2.52 2.82 3.36 3.75 5.85 7.67 16.85 1988 1.55 1.90 1.90 1.90 1.90 1.90 2.05 2.13 2.75 3.47 4.78 6.57 11.67 1987 1.81 2.43 2.54 2.54 2.87 2.87 3.38 3.62 3.62 5.31 5.31 9.80 13.86 1986 2.75 4.85 5.65 6.65 6.85 6.95 7.90 8.00 8.00 9.45 12.97 18.47 33.02 1985 --- --- --- --- --- --- --- --- --- --- --- --- 17.93 1984 --- --- --- --- --- --- --- --- --- --- --- --- 23.39 1983 --- --- --- --- --- --- --- --- --- --- --- --- 41.81 1982 --- --- --- 4.62 5.24 5.24 5.53 5.53 7.29 8.43 9.95 15.59 39.56 1981 2.04 2.94 3.80 4.17 4.32 5.01 6.02 6.02 6.21 6.21 6.62 11.24 17.15 1980 --- --- --- --- --- --- --- --- --- --- --- --- 26.42 D
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Section 13, Item J.
1979 1.54 2.28 2.83 3.82 3.82 3.82 4.02 4.97 5.49 6.53 7.09 12.65 20.87 1978 1.54 2.28 2.83 3.82 3.82 3.82 4.02 4.97 5.49 6.53 7.09 12.65 20.87 1977 0.92 1.03 1.09 1.12 1.12 1.12 1.24 1.26 1.26 1.26 2.18 3.32 8.73 1976 0.78 1.23 1.70 1.70 1.91 2.06 2.06 2.06 2.18 3.21 3.73 5.00 11.87 1975 1.97 2.56 3.14 3.27 3.38 3.52 4.84 6.08 7.82 8.47 8.50 15.06 28.24 1974 --- --- --- --- --- --- --- --- --- --- --- --- 33.80 1973 2.48 2.76 3.51 4.54 4.86 4.86 6.09 7.38 8.60 9.26 12.09 19.82 35.95 1972 3.05 3.88 3.92 3.98 3.98 5.03 5.90 5.96 6.05 6.73 7.92 9.62 16.80 1971 3.05 4.40 5.02 5.13 6.25 6.57 6.57 7.61 8.20 8.22 9.81 13.34 21.20 1970 2.94 2.94 3.48 3.48 3.72 3.72 4.97 5.90 6.37 7.01 9.55 12.27 21.13 1969 2.75 3.15 3.15 3.23 3.31 3.54 5.63 6.09 8.33 8.80 9.89 16.66 30.23 1968 1.76 2.12 2.12 2.43 2.43 2.48 2.51 3.20 3.20 3.49 4.61 8.77 17.12 1967 2.52 4.13 4.15 4.63 4.97 4.99 5.38 6.53 7.36 7.36 7.89 11.44 29.07 1966 1.79 1.95 2.46 2.48 3.27 3.74 4.03 4.13 5.17 5.17 5.17 9.69 16.47 1965 --- 3.43 --- --- --- --- --- 7.18 8.10 --- --- --- 25.01 1964 1.98 2.44 2.86 3.06 3.06 3.06 3.25 3.45 5.45 6.58 6.84 9.13 18.12 1963 2.88 3.52 4.20 4.65 4.65 4.65 4.65 4.65 6.07 6.38 6.38 10.35 24.44 1962 1.25 2.08 2.93 3.02 4.05 4.53 6.47 7.17 7.61 7.75 9.09 11.98 18.00 1961 1.38 1.68 2.16 2.16 2.16 2.26 2.40 2.77 2.93 3.23 4.81 6.51 13.82 1960 1.33 1.53 1.86 1.86 2.09 2.42 2.82 3.25 3.67 5.03 6.18 7.86 16.68 1959 1.65 2.09 2.09 2.55 2.88 3.22 3.68 4.01 4.01 4.75 6.13 10.54 13.45 1958 --- --- --- --- --- --- --- --- --- --- --- --- 41.69 1957 --- --- --- --- --- --- --- --- --- --- --- --- 18.93 1956 --- --- --- --- --- --- --- --- --- --- --- --- 28.58 1955 --- --- --- --- --- --- --- --- --- --- --- --- 18.28 1954 --- --- --- --- --- --- --- --- --- --- --- --- 16.40 1953 --- --- --- --- --- --- --- --- --- --- --- --- 15.10 1952 2.21 3.15 3.68 3.77 3.77 3.77 3.77 4.06 4.68 6.56 7.47 13.11 27.05 1951 4.65 5.30 5.30 5.30 5.55 5.70 6.24 6.25 6.25 8.87 10.85 14.60 28.76 1950 2.70 2.70 2.70 3.97 3.97 3.97 3.97 5.05 5.05 5.55 9.52 10.41 18.30 1949 1.76 2.71 3.14 3.14 3.14 3.14 3.72 3.86 4.87 5.45 6.93 10.49 17.23 1948 1.28 1.41 1.70 1.83 2.03 2.03 2.43 2.43 4.08 4.39 6.67 8.68 17.76 1947 2.16 3.12 3.20 3.20 3.91 3.91 3.91 4.13 4.13 4.13 4.82 7.33 14.54 1946 1.90 1.90 3.20 3.38 4.37 4.98 5.16 5.42 5.70 6.31 7.49 11.80 20.14 1945 2.68 3.88 4.78 4.78 4.98 5.27 5.27 5.27 5.66 5.66 5.66 9.58 23.66 1944 2.25 2.41 2.53 2.53 3.23 3.39 3.93 4.28 5.68 5.68 7.47 10.20 19.25 1943 2.05 2.78 3.58 3.81 4.43 4.77 5.38 5.42 7.10 8.03 10.13 15.90 27.61 1942 2.00 3.48 4.20 4.60 5.32 5.81 5.91 5.91 7.68 8.17 8.17 12.92 26.67 1941 1.85 2.40 2.46 3.46 5.46 5.46 4.17 4.52 7.17 8.59 11.13 14.00 25.17 1940 1.65 2.72 3.46 3.76 4.20 4.79 5.24 5.54 5.95 6.00 8.96 16.37 24.86 1939 1.72 2.40 2.55 2.80 2.80 2.80 2.80 2.80 2.80 3.17 3.42 5.93 14.01 1938 2.30 3.65 4.05 4.55 4.80 4.80 5.25 6.95 9.40 10.35 12.10 16.00 27.25 1937 4.40 4.65 5.85 6.15 6.60 6.95 7.70 8.15 8.70 9.50 10.10 19.90 34.99 1936 2.00 2.30 3.50 4.20 4.35 4.50 6.05 6.40 10.33 10.33 13.28 19.99 28.29 1935 2.50 2.72 2.72 2.72 3.25 4.30 4.52 4.52 5.22 5.65 6.35 9.47 23.94 1934 1.70 2.85 2.85 4.05 4.52 4.52 4.52 4.52 4.52 6.40 8.77 9.67 17.86 10/10/24, 2:23 PM Rainfall Depth Duration Frequency
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Section 13, Item J.
1933 1.20 1.72 1.72 1.72 2.32 3.12 3.12 3.82 3.82 3.82 5.07 7.87 12.77 1932 1.75 1.92 2.59 3.58 3.75 3.80 4.49 4.97 5.58 5.88 6.60 10.05 19.99 1931 1.65 1.65 1.65 2.53 2.53 2.53 2.65 2.65 2.65 2.65 3.92 6.39 12.62 1930 1.39 2.25 2.25 2.57 2.57 2.78 3.35 3.71 5.17 5.33 5.62 10.86 17.07 1929 1.91 2.98 3.49 3.49 3.49 3.49 3.49 3.57 4.07 4.07 4.07 6.57 15.52 1928 1.68 2.60 3.40 4.06 4.79 4.92 4.92 4.92 5.92 6.10 6.27 9.09 18.80 1927 1.50 3.00 3.00 4.25 4.25 4.51 5.46 5.96 6.26 6.91 7.41 10.51 24.11 1926 2.55 2.80 2.90 3.55 3.55 4.55 5.10 5.10 6.48 8.99 10.04 10.29 21.54 1925 1.95 3.05 3.27 3.27 3.52 3.74 4.27 5.79 5.94 7.79 8.41 11.84 28.60 1924 1.35 1.35 1.35 1.35 1.35 1.35 1.35 1.35 2.35 3.00 3.00 4.95 10.50 1923 2.20 3.00 4.30 5.30 5.30 5.30 5.50 6.10 6.70 6.70 9.30 14.15 26.07 1922 2.17 2.52 3.45 3.95 3.95 3.95 3.95 4.44 7.09 7.16 9.46 14.80 24.30 1921 3.85 3.95 4.50 4.72 4.72 4.72 4.72 5.72 6.62 7.02 7.72 13.51 26.57 1920 2.10 3.55 3.90 4.05 4.20 4.20 4.20 4.31 4.82 5.19 7.04 9.26 15.46 1919 2.25 3.55 3.90 4.00 4.05 4.40 4.60 4.70 5.00 6.45 8.15 10.35 18.75 1918 1.60 2.35 2.35 2.35 3.45 4.25 4.70 4.70 6.50 6.50 8.10 11.30 15.50 1917 1.30 2.30 2.60 2.90 3.25 3.55 4.10 4.35 4.55 4.55 5.35 7.25 17.70 1916 --- --- --- --- --- --- --- --- --- --- --- --- 20.00 1915 1.50 1.95 2.15 2.30 2.83 3.03 3.88 4.20 5.88 6.20 7.77 10.87 22.80 1914 2.26 3.11 3.49 3.61 3.99 3.99 3.99 4.48 5.47 6.96 9.81 13.52 22.90 1913 1.20 1.84 2.22 2.72 2.95 3.36 3.36 3.55 4.01 4.01 4.01 4.86 14.26 1912 0.69 1.04 1.15 1.22 1.30 1.45 1.86 2.16 2.47 2.86 3.43 5.36 12.68 1911 2.17 3.57 5.27 6.12 6.45 7.30 7.80 8.42 10.82 15.51 18.06 24.30 30.46 1910 2.00 3.00 3.00 3.45 3.88 3.88 3.93 3.93 4.00 4.69 5.92 8.90 20.89 1909 1.45 2.60 3.80 4.42 4.54 5.07 5.99 6.39 7.99 9.21 12.66 19.24 26.01 1908 1.30 1.60 1.60 1.78 1.78 1.78 1.83 3.03 3.63 3.63 5.51 9.04 14.27 1907 4.37 6.79 7.38 7.53 8.38 8.53 8.53 8.53 8.53 10.60 12.20 18.04 33.82 1906 2.40 2.54 3.22 3.62 3.85 3.85 3.85 5.03 7.47 9.20 10.45 15.43 30.93 1905 2.90 2.90 2.90 3.20 4.20 4.20 4.55 4.85 5.55 5.55 5.50 9.65 25.95 1904 1.51 2.62 3.12 3.15 3.15 3.25 3.75 4.86 6.07 6.42 7.20 12.05 21.42 1903 1.85 2.92 3.58 4.10 5.01 5.03 5.03 5.53 5.53 7.54 9.71 10.34 22.39 1902 1.21 1.79 2.09 2.61 3.01 3.41 3.87 4.41 5.03 6.03 7.72 9.29 20.19 1901 2.05 2.79 3.61 4.03 4.03 4.72 5.54 5.52 5.54 7.35 7.69 11.29 25.48 1900 1.85 2.34 2.41 2.80 2.86 2.86 2.86 3.88 4.82 5.66 6.45 9.69 21.51 1899 1.93 2.56 3.20 3.54 4.04 4.04 4.94 7.17 7.80 7.93 9.00 9.22 20.03 1898 3.60 4.47 4.64 4.64 4.64 4.64 4.64 4.76 5.11 5.11 5.23 7.30 13.77 1897 --- --- --- --- --- --- --- --- --- --- --- --- --- 1896 --- --- --- --- --- --- --- --- --- --- --- --- --- 1895 --- --- --- --- --- --- --- --- --- --- --- --- --- 1894 --- --- --- --- --- --- --- --- --- --- --- --- --- 1893 --- --- --- --- --- --- --- --- --- --- --- --- --- 1892 --- --- --- --- --- --- --- --- --- --- --- --- --- 1891 --- --- --- --- --- --- --- --- --- --- --- --- --- 1890 --- --- --- --- --- --- --- --- --- --- --- --- --- 1889 --- --- --- --- --- --- --- --- --- --- --- --- --- 1888 --- --- --- --- --- --- --- --- --- --- --- --- --- 10/10/24, 2:23 PM Rainfall Depth Duration Frequency
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Section 13, Item J.

California Irrigation Management Information System (CIMIS) Rendered in ENGLISH Units.Printed on Wednesday, August 31, 2022Average ETo Values by StationMonthly Average ETo Report Stn Id Stn Name CIMIS Region Jan
(in)
Feb
(in)
Mar
(in)
Apr
(in)
May
(in)
Jun
(in)
Jul
(in)
Aug
(in)
Sep
(in)
Oct(in)
Nov
(in)
Dec
(in)
Total
(in)
227 Plymouth SFH 1.48 1.95 3.02 4.57 5.97 7.19 7.64 6.98 4.99 3.24 1.68 1.21 49.92 CIMIS Region Abbreviations
BIS - Bishop CCV - Central Coast Valleys ICV - Imperial/Coachella Valley LAB - Los Angeles Basin MBY - Monterey Bay NCV - North Coast Valleys NEP - Northeast Plateau SAV - Sacramento Valley SBE - San Bernardino SFB - San Francisco Bay SJV - San Joaquin Valley SFH - Sierra Foothill SCV - South Coast Valleys

Section 13, Item J.

Turfgrass Performance Under Reduced Irrigation
Meyer and Gibeault
Attachment B
492
Section 13, Item J.

Class A Weather Bureau evaporation pan
measured evapotranspiration from experimental turfgrass plots at the UC South Coast Field Station at Irvine.

Turfgrass performance
under reduced irrigation
Jewel1 L. Meyer 0 Victor A. Gibeault
Turf grass in California requires irrigation during all or most of the year. Water restrictions imposed during the drought in
1976 and 1977 forced turf managers to
reexamine many concepts about irrigation. Turfgrass managers had to make drastic cuts in water use and hope that the
turf would survive. One significant result
of the drought was the realization that
lower levels of turf quality were acceptable in many situations and that large water savings could be achieved. No information was available, however, on the best conservation practices or on the
minimum amounts of water needed to
keep the turf alive.

Research was begun in 1979 to produce irrigation methodology that could be used to develop water-saving irrigation
practices anywhere in California and in
other arid and semiarid regions. The
three-year study showed that major savings of water can be achieved, especially with warm-season grasses, with no appreciable loss of turf quality.

Turf-irrigation study
Specifically, the objectives of the research were to: (1) investigate the effects of applying reduced amounts of irrigation
water calculated as a percentage of evapotranspiration of applied water on coolseason and warm-season turfgrasses; (2) evaluate a below-ground system as a potentially more efficient method of turf irrigation than standard sprinkler application; and (3) develop a set of crop coefficients that California turfgrass
managers can use to determine on-site
water use by both cool- and warm-season
turfgrasses.

The study was conducted at the University of California South Coast Field Station, Irvine. The variables tested included: two irrigation methods, sprinkler application of water and a subterranean
or buried trickle/drip water application
(8-inch depth, 23-inch spacing); three irrigation regimes, 100,80, and 60 percent of calculated evapotranspiration; and six
commonly used turfgrasses, three coolseason varieties (Kentucky bluegrass, perennial ryegrass, and tall fescue) and three warm-season types (hybrid bermudagrass, zoysiagrass, and Seashore Paspalum).

The field plot was a randomized splitblock design. The area was divided into two turf blocks, one for cool-season
grasses and the other for warm-season
grasses. Each block consisted of four replications, and within each replication were six randomized irrigation plots measuring 15 by 24 feet. Irrigation plots were divided into three turf subplots of 8 by 15
feet. The three sprinkler and three subterranean irrigation plots per replication were installed in September 1979 for
above- and below-ground water application. Each sprinkler irrigation plot contained six high-pop brass sprinkler heads designed to apply 10 gallons of water per
minute at a pressure of 35 pounds per
square inch. The coefficient of uniformity
was 87 percent.

Tensiometers at 3- and 6-inch depths in
the cool-season grasses and 8- and 12-inch
depths in the warm-season grasses indicated soil water status; neutron probe access tubes were installed in plots to a depth of 4 feet in the cool-season and 6
feet in the warm-season grasses. Scheduling was by the water budget technique calculated weekly using wind-modified
pan evaporation data. State-of-the-art
controllers were programmed with this
irrigation scheduling information. The
amount of irrigation was modified so that
water did not pass below the +foot and 6-
foot depths of the neutron probe access
tubes during the irrigation season.

Annual crop coefficients, determined
from previous research using applied water and evaporation pan data, were 0.7 annually for warm-season grasses and 0.8
for cool-season grasses. Monthly crop coefficients were developed in this experiment to evaluate responses of the six turfgrass species to 60 percent and 80 percent of replacement evapotranspiration for
water conservation.

Turf performance
Overhead sprinkler irrigation provided acceptable performance of some turfgrass species, even when less than the
optimum amount of water was applied.

Subterranean irrigation did not provide
acceptable turf with the shallow-rooted
cool-season species, at the system depth
and spacing used in this study. The very
deeply rooted hybrid bermudagrass was
the best-performing species with subterranean irrigation.

Under sprinkler irrigation, there was
no significant difference in cool-season
grass performance between the 100 percent and 80 percent regimes (table 1). This could be described as a potential level of
water conservation amounting to 21.1
percent savings (77.2 inches versus 61
inches). The savings could be tenuous,
however, because of more weed and disease activity (such as Gerlachia patch on Kentucky bluegrass) when irrigated with
less than the optimum amount of water.

The 60 percent regime significantly reduced the turf quality of the three coolseason grasses tested.

In the warm-season grasses, the appearance of hybrid bermudagrass and Seashore Paspalum was not significantly
different under any of the irrigation regimes. As irrigation amounts were reduced, zoysiagrass appearance ratings declined because of nematode activity obCALIFORNIA AGRICULTURE, JULY-AUGUST 1986 19 493 Section 13, Item J.
served on the roots. Both Santa Ana hybrid bermudagrass and Adalayd (Excalibre) Seashore Paspalum had very good color, density, texture, uniformity, and
freedom from weeds and diseases, irrespective of irrigation regimes. Clearly there is potential for considerable water
savings with these grasses. This study
showed a 40 percent reduction in actual
water applied between the optimum and
lowest irrigation regime (65.5 versus 39
inches).

Because of the field plot design necessary for this study, it wasn't possible to compare statistically the turf performance results between the warm- and cool-season grasses. Hybrid bermuda and
Seashore Paspalum performed very well,
however, with 52.7 inches of water applied (60 percent irrigation regime), whereas the cool-season grasses needed
at least 82.4 inches (80 percent irrigation
regime). Thirty-six percent less water
was applied to the warm-season species
than to the cool-season species for acceptable turf quality. If applied water in the 60 percent irrigation treatment in warmseason grasses (52.7 inches) is compared with that in the 100 percent treatment in
cool-season grasses (104.4 inches), the
saving in water is 49.5 percent.

Water application
The cool-season grass in the 100 percent regime received 43 inches of water in 1982 (table 2). Warm-season grasses received only 34 inches. Rainfall of 18.45 inches occurred primarily from November to March. The soil profile held about 10 inches depth of water in the top 6 feet.

Rainfall did not appreciably affect the applied water during the primary growing season, April through November. Likewise, the 34 inches applied to the warmTABLE 1. Cool- and warm-season turfgrass appearance ratings and water applied for the duration of the study (August 1981 to December 1983).

Irrigation Water appliregime Turf appearance 8/61 - 12/83' cation (actual) ET.,...t % of ET in.

Cool season Ken. blue Per. rye Tall fesc.
100 5.5 y 6.2 y 5.8 y 104.4 77.3
80 5.3 y 5.9 y 5.7 yz 82.4 61 .O
60 4.8 z 5.0 z 5.3 z 62.7 46.4
100 6.5 ns+ 5.8 ns 5.6 x 88.4 65.5
80 6.5 5.8 4.8 y 69.4 51.4
60 6.4 5.4 4.2 z 52.7 39.0
Warm season Bermuda Paspalum Zoysia
* Rated on a scale of 1 to 9, with 1 indicating worst appearance and 9 best. Values followed by common letters are not t ETgrass equals the actual applied water divided by the extra water factor (EWF,,). which is 1.35. $ No significant difference.
significantly different at the 5% level of probability.

TABLE 2. Actual water applied in 1982 (1/1/82 to 12/31/82) and 1983 (1/1/83 to 12/31/83) Sprinkler
DlOtS
% of ET
Cool season
100
80 60
100
80 60
Warm season
1982 1983
Water applied' Rainfall Water appliedt Rainfall

43.2 35.0

26.6 34.0

27.4 21.6

18.45 38.7 31.78

31.9 24.5

33.0 25.8

19.6 ' Class A pan evaporation 55.0 inches for 1982.
t Class A pan evaporation 55.63 inches for 1983.

TABLE 3. Turfgrass crop coefficients (Kp and Kc) of warm- and cool-season grasses.

KD' Kc+ ..

Month Warm Cool Warm Cool
J
F
M
A
M
J
J
A
S
0 N
D
.44
.43
.61
.58
.63
54 57
.57
.50
.43
.46
.44
.49
.51
.60
.83
.76
.70
.75
.69
59 .60
.55
.48
.55
.54
.76
.72
.79
.68
.71
.71
.62
54 58
55 .61
.64
.75

1.04 .95
.88
.94
.86
.74
.75
.69
.60
' Monthly crop coefficient (Kp) is used with a Class A Weather Bureau evaporation pan with the equation ETgrass = t The crop coefficient Kc is used with reference evapotranspiratlon (ETo) from a ClMlS weather station with the equation ETpan X KP
ETgrass = ETo x Kc
20 CALIFORNIA AGRICULTURE, JULY-AUGUST 1986
season grasses was not appreciably affected by, nor was there evidence of, deep percolation during the primary growing
season, when only 4 inches of rain fell.

The rainfall is subtracted from the original evaporation pan reading and is therefore reasonably accounted for in the calculated applications.

In 1983, a higher than normal rainfall
of 32 inches occurred. The soil profile was
filled during the winter, however, and
only 9 inches of rain fell from April to
October 30, of which 4 inches occurred in
early April. Water moved below the root
zone only on June 29, August 29, October
5, and October 17 in all plots of 100 and 80
percent irrigation in 1983. Even during a
season of higher than normal rainfall, the
applied water, 38.7 inches in cool-season
grasses (1983), was similar to that of the
drier year (1982) with 43 inches applied.

Most of the 5 inches of implied higher use
by cool-season grasses may have moved
through deep percolation.

The water applied to warm-season
grasses was 34 inches in 1982 and 33
inches in 1983. This small difference indicates that managers can schedule carefully and conserve water in a wet or dry season.

Conclusions
The monthly crop coefficients (table 3)
calculated and used for nearly three years
proved to be very accurate for both
warm- and cool-season turfgrasses. Crop
coefficients can be used with reference
evapotranspiration from the Department
of Water Resources California Irrigation
Management Information System (CIMIS) program. Turfgrass managers can use these crop coefficients to determine
on-site water use by turfgrasses from either a Class A Weather Bureau evaporation pan or from a computerized weather station that gives reference evapotranspiration with the equation given in table 3.

In conclusion, warm-season turfgrasses have a greater potential for water conservation than do cool-season turfgrasses. Under the conditions of this study, sprinkler irrigation was superior to
subterranean irrigation for water conservation and turfgrass performance. And lastly, a well-designed, uniform irrigation
system is necessary to maximize water
conservation in turfgrass management.

Jewel1 L. Meyer is Irrigation and Soils S ecialist and
Victor A. Cibeault is Environmental drticulturist,
Cooperative Extension, University of California,
Riverside. Financial support for this study was granted by the Metropolitan Water District of South- ern California, City of Los Angeles Department of Water and Power, Municipal Water District of Orange County, and the San Diego County Water Authority. Also the support of the Southern California Turfgrass Council, the Lloyd Foundation, and the
Golf Course Superintendent's Association of Southern
California is appreciated. The authors acknowledge
the assistance of Ralph Strohman and Mark Mahody, Staff Research Associates. UC Riverside. 494
Section 13, Item J.

Water Application Efficiency,
Bill Kranz, University of Nebraska Lincoln Extension
Irrigation Specialist,
Northeast Research and Extension Center
Attachment C
495
Section 13, Item J.

Plant & Soil Sciences eLibrary (/) Lessons(/list/lesson) Collections & Categories(/list/community) Media(/view/media) LESSON: IRRIGATION HOME STUDY COURSE (/VIEW/LESSON/BDA727EB8A5A) / PAGE 8: IRRIGATION CHAPTER 8 - IRRIGATION EFFICIENCIES Irrigation Chapter 8 - Irrigation Efficiencies
Author: Bill Kranz, University of Nebraska Lincoln Extension Irrigation Specialist, Northeast Research and Extension Center, Norfolk, NE.

Water Application
The ability to manage an irrigation system is contingent on an accurate estimate of the percentage of water pumped that becomes available for crop use. No irrigation system delivers water at 100 percent efficiency. Water may be lost through delivery systems or pipelines and some water may remain in the , but not be used by the crop. Some water may run off the soil surface into lowland areas. Still other water may be lost to evaporation in the air, or from the soil and plant surfaces. Figures 8.1a and 8.1b show the major losses for sprinkler and surface irrigation systems. To know how much water to pump, these losses must be totaled and added to the amount of water needed by the crop.

Figure 8.1. a) Potential water losses during irrigation with a center pivot. b) Potential water losses during irrigation with a system.

In most cases, the goal is to insure that all areas of the field receive a amount of uniformly applied water. Consider the catch can test data shown in Figure 8.2. The cans recording application depths below the horizontal line are not receiving enough water — catches are less than the desired 0.85 inches. Another application will be needed to insure that the entire field receives at least 0.85 inches of water. This will require using more water and energy than is necessary. If this pattern occurs during each irrigation, plants in the areas receiving less than 0.85 inches eventually could experience water stress.

The cans recording application depths above the line receive at least 0.85 inches of water. Any extra water applied could lead to surface or deep .

Efficiency
soil
furrow irrigation
set
runoff percolation
496
Section 13, Item J.

Figure 8.2. Example of catch-can data from a center pivot with low pressure spray nozzle, mounted at 10 foot intervals and 7 feet above the soil surface.

Water application efficiency accounts for how uniformly the water is applied and can be used for other assessments. If the center pivot owner is trying to decide whether switching to a new sprinkler package would be economical, the change in water application efficiency could be a major factor. If water becomes limited, changing to a system with a higher water application efficiency will provide more useable water to the crop and reduce pumping costs.

To maximize irrigation water use, it must be uniformly applied in the right amount and at the right time. Reaching these objectives requires knowledge of water delivery characteristics, field soils and slopes, and the expected crop water use rates.

Mathematical relationships have been developed to help quantify the amount of applied water that becomes available for plant use.

Water application efficiency refers to the amount of water applied that is stored in the crop root zone. This value is determined by water distribution characteristics, system management, soil conditions, the crop, and weather conditions.

Water application efficiency pertains to an individual irrigation event.

Equation 8.1 is used to determine water application efficiency.

Equation 8.1 E = [Depth of water stored in the rootzone (d ) x 100 Depth of water pumped (d ) ]
where:

E = Average water application efficiency, %
Depth of water stored in the rootzone (d ) = Average depth of water stored in the rootzone, inches Depth of water pumped (d = Average depth of water delivered from source, inches Irrigation efficiency refers to the amount of water removed from the water source that is used by the crop. This value is determined by irrigation system management, water distribution characteristics, crop water use rates, weather and soil conditions. Irrigation efficiency pertains to the use of water for an entire growing season. a s
p
a
s
p)
497
Section 13, Item J.

Depth Stored
The depth of water stored in the root zone can be estimated based on field observation of what happens to the water during an application event. Field observation reports should note if runoff occurs and estimate the amount of runoff. With experience, you’ll begin to know where and when runoff is likely to occur. For example, runoff from center pivot systems will likely occur first near the outside edge of the irrigated area because the water application rate is greatest there. Other factors include low rate soils, steep slopes and lack of plant residue cover.

Another more accurate method is to record the content before and after an irrigation event using one of the methods discussed in Chapter 3, Soil Water. If the hand-feel method is used, the will need to be recorded at enough locations to develop accurate estimates of the water stored in the crop root zone. The depth of water applied is found by subtracting the reading taken before the irrigation.

Equation 8.2 d = [“After” reading – “Before” reading]
Where:
d = Depth of water stored in the rootzone
Example 8.1
A center pivot irrigation system is supplied with enough water to apply 1.1 inches of water to an irrigated area. Soil water content readings recorded before the irrigation event showed an average water content of 3.5 inches in the top 3 feet of soil.

Soil water content readings after the irrigation showed an average of 4.4 inches in the top 3 feet of soil. To find the average depth of water stored in the crop rootzone we subtract the before irrigation reading from the after irrigation reading.

Using Equation 8.2 d = [“After” reading – “Before” reading] d = [ 4.4 inches – 3.5 inches ]
d = 0.9 inches
Depth Pumped
The depth of water pumped can be determined using the procedures presented in Chapter 7, Flow Measurements and Basic Water Calculations. The information needed includes an accurate estimate of the pumping rate in gallons per minute. This information can be recorded using a flow meter installed as part of the system or periodically using an attached flow meter (ultrasonic flow meter, pilot tube type meter, etc.).

The average flow rate can be determined by recording the accumulator reading prior to and after each irrigation event.

Subtracting the reading recorded prior to the irrigation from the reading after the irrigation event will result in the total volume of water pumped. Taking the total volume and dividing by the irrigation time will give the average pumping rate. For this estimate to be accurate, the irrigation time must be accurate to the nearest hour if possible. A more precise record of the total irrigation time will improve the estimate of the pumping flow rate. (The hour meter on the motor or center pivot is accurate enough to estimate the pumping time.) Equations 8.3 and 8.4 are used to make these calculations. The following example shows how to incorporate field data into the equations.

Equation 8.3 Pumping rate = [ Reading 2 – Reading 1 ] / [ Time ] where:

Pumping rate = Water deliver rate, gallons per minute or acre-inches per minute infiltration
soil water
soil water content
s
s
s
s
s
498
Section 13, Item J.

Reading 1 = Totalizer reading before the irrigation event, gallons or acre-inches Reading 2 = Totalizer reading after the irrigation event, gallons or acre-inches Time = Time required to complete the irrigation event, minutes Example 8.2
The meter also has an accumulator at the bottom that registers total gallons pumped. Before the irrigation event, the accumulator reading was 6,553,300 gallons, and after the irrigation event the meter read 10,167,500 gallons. The irrigation event required 77 hours and 15 minutes.

Using Equation 8.3
Pumping rate = [ Reading 2-Reading 1 ] / [ Time ]
Pumping rate = [ 10,167,500 - 6,553,300 ] gallons [(77 hr x 60 min/hr ) + 15 min ] Pumping rate = [ 3,614,200 ] gallons / [ 4620 + 15 ] minutes Pumping rate = 780 gallons per minute
If the accumulator records flow in acre-inches, the same process is used unless the desire is to determine the flow rate in gallons per minute. To convert acre-inches per minute to gallons per minute, multiply the result from Equation 8.3 in acreinches per minute by 27,154 gallons per acre-inch.

To convert the flow rate in gallons per minute to the gross depth of water pumped, we use Equation 8.4. If the result from Equation 8.3 is in acre-inches per minute, the constant 27,154 gallons per acre-inch is not used.

Equation 8.4 d = [flow rate x time ] / [area irrigated x 27,154] where:
d = Depth pumped = Average depth of water pumped, inches Flow rate = Average water delivery rate, gallons per minute Time = Total irrigation time, minutes
Area irrigated = Total irrigated area, acres
27,154 = Conversion factor, gallons per acre-inch or gal / ac-in Example 8.3
Let’s assume that the field area for Example 8.2 was 123 acres. We calculated the flow rate at 780 gallons per minute and the total irrigation time at 4635 minutes. Using Equation 8.3:

Depth pumped (d ) = [ Flow rate x time ] / [ Area irrigated x 27,154 ] Depth pumped (d ) = [ 780 gal/min x 4635 minutes ] [ 123 acres x 27154 gal / ac-in ] Depth pumped (d ) = [ 3,615,300 ]gallons / [ 3,339,942 ] gallons / inch Depth pumped (d ) = 1.08 inches
p
p
p
p
p
p
499
Section 13, Item J.

To complete the calculation of the water application efficiency, use Equation 8.1 to compare the amount of water pumped with the increase in water stored in the crop rootzone.

Example 8.4
From Example 8.1 we found that 0.9 inches of water was stored in the three-foot crop rootzone. From Example 8.3 we found that 1.08 inches of water was pumped from the water source into the center pivot. To find the application efficiency we use Equation 8.1.

E = [ Depth of water stored in the rootzone (d ) x 100 Depth of water pumped (d ) ] E = [ 0.9 inches / 1.08 inches ] x 100
E = 83%
In these examples it was determined that only 83 percent of the water pumped from the irrigation source reached the soil and was usable by the crop. That means that 17 percent of the water was lost during application.

Potential Delivery Losses
The amount of water loss due to irrigation depends of the type of irrigation system — sprinkler or surface. In addition, the magnitude of each type of loss may be different. Let’s begin by listing some major sources of water loss during irrigation. To keep the losses for surface and sprinkler irrigation separate, Table 8.1 lists the potential losses for each type of system.

Table 8.1. Potential sources of water loss during an irrigation event for surface and sprinkler irrigation systems.

Sources of water losses Surface Irrigation Sprinkler irrigation Distribution system Yes
Yes
Air evaporation No Yes
Plant interception No Yes
Soil evaporation Yes Yes
Deep percolation Yes Yes
Runoff Yes Yes
Surface Irrigation Systems
The major losses for surface irrigation systems are deep percolation and surface runoff. These two losses could cause the water application efficiency to be reduced to less than 50 percent if the system is not managed properly. Ways to minimize these losses are discussed in Chapter 11, Furrow Irrigation Management (https://passel2.unl.edu/view/lesson/bda727eb8a5a/11).
a s p
a
a
500
Section 13, Item J.

Another source of water loss is in the distribution system. If the water flows across the head of the field in an open ditch, each foot of ditch loses water to soil infiltration and water surface evaporation. The best way to eliminate these losses is to transport the water through an enclosed pipeline. For many furrow irrigated fields this will require a small pumping plant to overcome the friction loss associated with forcing water through the pipeline.

Surface irrigation implies that surface evaporation will contribute to water loss. One way to limit soil evaporation loss is to wet less of the soil surface. For fields with slopes less than 1 percent, irrigating every other furrow is a viable option. This effectively cuts surface evaporation losses by nearly 50 percent without sacrificing crop production. Irrigating every other furrow also will reduce the amount of water lost to deep percolation and surface runoff.

Pipelines can have losses too. Worn gaskets or loose fitting pipeline connections could produce leaks at each joint. These losses are usually small in comparison to other losses, but by their sheer number could add up to substantial water losses.

This kind of loss is the easiest to eliminate by replacing gaskets.

Sprinkler Irrigation Systems
Sprinkler irrigation systems, especially center pivots, typically have greater water application efficiencies than surface systems. While they may have more potential sources of loss, the magnitude of each loss is generally quite low. Table

8.1 shows that sprinkler irrigation systems may experience loss from all six of the potential water loss sources while surface irrigation systems lose water from only four. This is because most sprinkler irrigation systems spray water into the air to deliver water to the entire soil surface with an upright crop canopy located between the sprinkler and soil.

Developments in sprinkler technology have reduced the amount of water lost between the sprinkler/nozzle and soil surface.

The irrigation time or the accumulated time that water is applied to the crop canopy causes the major loss during sprinkler irrigation events. Applied water evaporates off the leaves of the crop canopy. Thus, the longer water droplets are delivered to the crop, the greater the total evaporation loss. Lowering the sprinkler/nozzle pressure reduces the wetted diameter of the sprinkler/nozzle thus reducing irrigation time and total canopy evaporation losses. In addition, lower wetted diameters reduce water evaporation losses in the air and wind drift losses.

Proper management of sprinkler irrigation systems can greatly reduce deep percolation losses. An irrigation system managed to keep the soil profile completely full at all times will experience some deep percolation losses. This is because the system does not apply water at 100 percent uniformity. Some areas will receive more water than others due to sprinkler pressure differences caused by soil elevation differences. Pressure regulators or flow control nozzles help insure that water delivered to the soil surface is as uniform as possible. Other portions of the field could be affected when wind distorts the water application pattern. Such distortion can be reduced by avoiding operation when winds exceed 10 mph.

How do I Evaluate Losses?
There are two main ways to evaluate water loss during irrigation: 1) take detailed field measurements; and 2) visually estimate losses. In some cases it may be necessary to combine these methods to develop an accurate estimate of where losses occur and how significant they are to the system’s application efficiency. For example, to estimate water losses during irrigation, measure the flow rate of water entering the system with a flow meter. Visually estimate how much of the water is lost to runoff. This amount, however, will not account for other potential losses. Table 8.2 presents the potential magnitude of some of these losses for different irrigation systems. For furrow irrigation systems record how long it takes for the water to reach a certain point in the field or record flow rates into the furrow and how long it takes water to reach the end of the furrow.

When coupled with soil types and furrow slopes, a computer model can be used to estimate how efficiently the water is being applied.

Table 8.2a. Percent irrigation water losses for different furrow irrigation systems. 501
Section 13, Item J.

Type of
irrigation
system
Distribution
system
Air
evaporation
Soil
evaporation
Canopy
evaporation
Deep
percolation
Surface
runoff
Overall
efficiency
Every row 1-5 <1.0 1--5 0.0 10-20 10-35 40-75
W/Surge
valve
1-5 <1.0 1-5 0.0 5-15 5-15 60-85
W/Reuse 1-5 1-2 1-5 0.0 10-20 0 55-90
Siphon
tube
5-10 1-2 1-5 0.0 15-25 15-25 40-75
Alternate
row
1-5 <0.5 1-5 0.0 5-15 10-20 60-85
Table 8.2b. Percent irrigation water losses for different Sprinkler Irrigation systems.

Type of
irrigation
system
Distribution
system
Air
evaporation
Soil
evaporation
Canopy
evaporation
Deep
percolation
Surface
runoff
Overall
efficiency
Handmove <1.0 3-5 1-5 10-15 5-10 0-5 60-80
Solid set <1.0 3-5 1-5 10-15 0-10 0-5 60-85
Traveler <1.0 1-3 1-5 1-5 0-5 5-10 55-75
High
pressure
impact
<0.5 1-3 0-1 1-5 0-5 0-5 70-80
Low
pressure
impact
<0.5 1-3 0-1 1-3 0.5 0-10 75-85
Low
pressure
spray
<0.5 1-3 0-1 1-3 0-5 0-20 70-90
Low
pressure
bubble
<0.5 0.0 0-0.5 0.0 0-5 20-40 60-95
Drip
irrigation
<0.5 0.0 0.0 0.0 5-30 0.0 70-95
502
Section 13, Item J.

Irrigation Efficiency
Attachment E
503
Section 13, Item J.

Plant & Soil Sciences eLibrary (/) Lessons(/list/lesson) Collections & Categories(/list/community) Media(/view/media) LESSON: IRRIGATION HOME STUDY COURSE (/VIEW/LESSON/BDA727EB8A5A) / PAGE 8: IRRIGATION CHAPTER 8 - IRRIGATION EFFICIENCIES Irrigation Chapter 8 - Irrigation Efficiencies
Author: Bill Kranz, University of Nebraska Lincoln Extension Irrigation Specialist, Northeast Research and Extension Center, Norfolk, NE.

Water Application
The ability to manage an irrigation system is contingent on an accurate estimate of the percentage of water pumped that becomes available for crop use. No irrigation system delivers water at 100 percent efficiency. Water may be lost through delivery systems or pipelines and some water may remain in the , but not be used by the crop. Some water may run off the soil surface into lowland areas. Still other water may be lost to evaporation in the air, or from the soil and plant surfaces. Figures 8.1a and 8.1b show the major losses for sprinkler and surface irrigation systems. To know how much water to pump, these losses must be totaled and added to the amount of water needed by the crop.

Figure 8.1. a) Potential water losses during irrigation with a center pivot. b) Potential water losses during irrigation with a system.

In most cases, the goal is to insure that all areas of the field receive a amount of uniformly applied water. Consider the catch can test data shown in Figure 8.2. The cans recording application depths below the horizontal line are not receiving enough water — catches are less than the desired 0.85 inches. Another application will be needed to insure that the entire field receives at least 0.85 inches of water. This will require using more water and energy than is necessary. If this pattern occurs during each irrigation, plants in the areas receiving less than 0.85 inches eventually could experience water stress.

The cans recording application depths above the line receive at least 0.85 inches of water. Any extra water applied could lead to surface or deep .

Efficiency
soil
furrow irrigation
set
runoff percolation
504
Section 13, Item J.

Figure 8.2. Example of catch-can data from a center pivot with low pressure spray nozzle, mounted at 10 foot intervals and 7 feet above the soil surface.

Water application efficiency accounts for how uniformly the water is applied and can be used for other assessments. If the center pivot owner is trying to decide whether switching to a new sprinkler package would be economical, the change in water application efficiency could be a major factor. If water becomes limited, changing to a system with a higher water application efficiency will provide more useable water to the crop and reduce pumping costs.

To maximize irrigation water use, it must be uniformly applied in the right amount and at the right time. Reaching these objectives requires knowledge of water delivery characteristics, field soils and slopes, and the expected crop water use rates.

Mathematical relationships have been developed to help quantify the amount of applied water that becomes available for plant use.

Water application efficiency refers to the amount of water applied that is stored in the crop root zone. This value is determined by water distribution characteristics, system management, soil conditions, the crop, and weather conditions.

Water application efficiency pertains to an individual irrigation event.

Equation 8.1 is used to determine water application efficiency.

Equation 8.1 E = [Depth of water stored in the rootzone (d ) x 100 Depth of water pumped (d ) ]
where:

E = Average water application efficiency, %
Depth of water stored in the rootzone (d ) = Average depth of water stored in the rootzone, inches Depth of water pumped (d = Average depth of water delivered from source, inches Irrigation efficiency refers to the amount of water removed from the water source that is used by the crop. This value is determined by irrigation system management, water distribution characteristics, crop water use rates, weather and soil conditions. Irrigation efficiency pertains to the use of water for an entire growing season. a s
p
a
s
p)
505
Section 13, Item J.

Depth Stored
The depth of water stored in the root zone can be estimated based on field observation of what happens to the water during an application event. Field observation reports should note if runoff occurs and estimate the amount of runoff. With experience, you’ll begin to know where and when runoff is likely to occur. For example, runoff from center pivot systems will likely occur first near the outside edge of the irrigated area because the water application rate is greatest there. Other factors include low rate soils, steep slopes and lack of plant residue cover.

Another more accurate method is to record the content before and after an irrigation event using one of the methods discussed in Chapter 3, Soil Water. If the hand-feel method is used, the will need to be recorded at enough locations to develop accurate estimates of the water stored in the crop root zone. The depth of water applied is found by subtracting the reading taken before the irrigation.

Equation 8.2 d = [“After” reading – “Before” reading]
Where:
d = Depth of water stored in the rootzone
Example 8.1
A center pivot irrigation system is supplied with enough water to apply 1.1 inches of water to an irrigated area. Soil water content readings recorded before the irrigation event showed an average water content of 3.5 inches in the top 3 feet of soil.

Soil water content readings after the irrigation showed an average of 4.4 inches in the top 3 feet of soil. To find the average depth of water stored in the crop rootzone we subtract the before irrigation reading from the after irrigation reading.

Using Equation 8.2 d = [“After” reading – “Before” reading] d = [ 4.4 inches – 3.5 inches ]
d = 0.9 inches
Depth Pumped
The depth of water pumped can be determined using the procedures presented in Chapter 7, Flow Measurements and Basic Water Calculations. The information needed includes an accurate estimate of the pumping rate in gallons per minute. This information can be recorded using a flow meter installed as part of the system or periodically using an attached flow meter (ultrasonic flow meter, pilot tube type meter, etc.).

The average flow rate can be determined by recording the accumulator reading prior to and after each irrigation event.

Subtracting the reading recorded prior to the irrigation from the reading after the irrigation event will result in the total volume of water pumped. Taking the total volume and dividing by the irrigation time will give the average pumping rate. For this estimate to be accurate, the irrigation time must be accurate to the nearest hour if possible. A more precise record of the total irrigation time will improve the estimate of the pumping flow rate. (The hour meter on the motor or center pivot is accurate enough to estimate the pumping time.) Equations 8.3 and 8.4 are used to make these calculations. The following example shows how to incorporate field data into the equations.

Equation 8.3 Pumping rate = [ Reading 2 – Reading 1 ] / [ Time ] where:

Pumping rate = Water deliver rate, gallons per minute or acre-inches per minute infiltration
soil water
soil water content
s
s
s
s
s
506
Section 13, Item J.

Reading 1 = Totalizer reading before the irrigation event, gallons or acre-inches Reading 2 = Totalizer reading after the irrigation event, gallons or acre-inches Time = Time required to complete the irrigation event, minutes Example 8.2
The meter also has an accumulator at the bottom that registers total gallons pumped. Before the irrigation event, the accumulator reading was 6,553,300 gallons, and after the irrigation event the meter read 10,167,500 gallons. The irrigation event required 77 hours and 15 minutes.

Using Equation 8.3
Pumping rate = [ Reading 2-Reading 1 ] / [ Time ]
Pumping rate = [ 10,167,500 - 6,553,300 ] gallons [(77 hr x 60 min/hr ) + 15 min ] Pumping rate = [ 3,614,200 ] gallons / [ 4620 + 15 ] minutes Pumping rate = 780 gallons per minute
If the accumulator records flow in acre-inches, the same process is used unless the desire is to determine the flow rate in gallons per minute. To convert acre-inches per minute to gallons per minute, multiply the result from Equation 8.3 in acreinches per minute by 27,154 gallons per acre-inch.

To convert the flow rate in gallons per minute to the gross depth of water pumped, we use Equation 8.4. If the result from Equation 8.3 is in acre-inches per minute, the constant 27,154 gallons per acre-inch is not used.

Equation 8.4 d = [flow rate x time ] / [area irrigated x 27,154] where:
d = Depth pumped = Average depth of water pumped, inches Flow rate = Average water delivery rate, gallons per minute Time = Total irrigation time, minutes
Area irrigated = Total irrigated area, acres
27,154 = Conversion factor, gallons per acre-inch or gal / ac-in Example 8.3
Let’s assume that the field area for Example 8.2 was 123 acres. We calculated the flow rate at 780 gallons per minute and the total irrigation time at 4635 minutes. Using Equation 8.3:

Depth pumped (d ) = [ Flow rate x time ] / [ Area irrigated x 27,154 ] Depth pumped (d ) = [ 780 gal/min x 4635 minutes ] [ 123 acres x 27154 gal / ac-in ] Depth pumped (d ) = [ 3,615,300 ]gallons / [ 3,339,942 ] gallons / inch Depth pumped (d ) = 1.08 inches
p
p
p
p
p
p
507
Section 13, Item J.

To complete the calculation of the water application efficiency, use Equation 8.1 to compare the amount of water pumped with the increase in water stored in the crop rootzone.

Example 8.4
From Example 8.1 we found that 0.9 inches of water was stored in the three-foot crop rootzone. From Example 8.3 we found that 1.08 inches of water was pumped from the water source into the center pivot. To find the application efficiency we use Equation 8.1.

E = [ Depth of water stored in the rootzone (d ) x 100 Depth of water pumped (d ) ] E = [ 0.9 inches / 1.08 inches ] x 100
E = 83%
In these examples it was determined that only 83 percent of the water pumped from the irrigation source reached the soil and was usable by the crop. That means that 17 percent of the water was lost during application.

Potential Delivery Losses
The amount of water loss due to irrigation depends of the type of irrigation system — sprinkler or surface. In addition, the magnitude of each type of loss may be different. Let’s begin by listing some major sources of water loss during irrigation. To keep the losses for surface and sprinkler irrigation separate, Table 8.1 lists the potential losses for each type of system.

Table 8.1. Potential sources of water loss during an irrigation event for surface and sprinkler irrigation systems.

Sources of water losses Surface Irrigation Sprinkler irrigation Distribution system Yes
Yes
Air evaporation No Yes
Plant interception No Yes
Soil evaporation Yes Yes
Deep percolation Yes Yes
Runoff Yes Yes
Surface Irrigation Systems
The major losses for surface irrigation systems are deep percolation and surface runoff. These two losses could cause the water application efficiency to be reduced to less than 50 percent if the system is not managed properly. Ways to minimize these losses are discussed in Chapter 11, Furrow Irrigation Management (https://passel2.unl.edu/view/lesson/bda727eb8a5a/11).
a s p
a
a
508
Section 13, Item J.

Another source of water loss is in the distribution system. If the water flows across the head of the field in an open ditch, each foot of ditch loses water to soil infiltration and water surface evaporation. The best way to eliminate these losses is to transport the water through an enclosed pipeline. For many furrow irrigated fields this will require a small pumping plant to overcome the friction loss associated with forcing water through the pipeline.

Surface irrigation implies that surface evaporation will contribute to water loss. One way to limit soil evaporation loss is to wet less of the soil surface. For fields with slopes less than 1 percent, irrigating every other furrow is a viable option. This effectively cuts surface evaporation losses by nearly 50 percent without sacrificing crop production. Irrigating every other furrow also will reduce the amount of water lost to deep percolation and surface runoff.

Pipelines can have losses too. Worn gaskets or loose fitting pipeline connections could produce leaks at each joint. These losses are usually small in comparison to other losses, but by their sheer number could add up to substantial water losses.

This kind of loss is the easiest to eliminate by replacing gaskets.

Sprinkler Irrigation Systems
Sprinkler irrigation systems, especially center pivots, typically have greater water application efficiencies than surface systems. While they may have more potential sources of loss, the magnitude of each loss is generally quite low. Table

8.1 shows that sprinkler irrigation systems may experience loss from all six of the potential water loss sources while surface irrigation systems lose water from only four. This is because most sprinkler irrigation systems spray water into the air to deliver water to the entire soil surface with an upright crop canopy located between the sprinkler and soil.

Developments in sprinkler technology have reduced the amount of water lost between the sprinkler/nozzle and soil surface.

The irrigation time or the accumulated time that water is applied to the crop canopy causes the major loss during sprinkler irrigation events. Applied water evaporates off the leaves of the crop canopy. Thus, the longer water droplets are delivered to the crop, the greater the total evaporation loss. Lowering the sprinkler/nozzle pressure reduces the wetted diameter of the sprinkler/nozzle thus reducing irrigation time and total canopy evaporation losses. In addition, lower wetted diameters reduce water evaporation losses in the air and wind drift losses.

Proper management of sprinkler irrigation systems can greatly reduce deep percolation losses. An irrigation system managed to keep the soil profile completely full at all times will experience some deep percolation losses. This is because the system does not apply water at 100 percent uniformity. Some areas will receive more water than others due to sprinkler pressure differences caused by soil elevation differences. Pressure regulators or flow control nozzles help insure that water delivered to the soil surface is as uniform as possible. Other portions of the field could be affected when wind distorts the water application pattern. Such distortion can be reduced by avoiding operation when winds exceed 10 mph.

How do I Evaluate Losses?
There are two main ways to evaluate water loss during irrigation: 1) take detailed field measurements; and 2) visually estimate losses. In some cases it may be necessary to combine these methods to develop an accurate estimate of where losses occur and how significant they are to the system’s application efficiency. For example, to estimate water losses during irrigation, measure the flow rate of water entering the system with a flow meter. Visually estimate how much of the water is lost to runoff. This amount, however, will not account for other potential losses. Table 8.2 presents the potential magnitude of some of these losses for different irrigation systems. For furrow irrigation systems record how long it takes for the water to reach a certain point in the field or record flow rates into the furrow and how long it takes water to reach the end of the furrow.

When coupled with soil types and furrow slopes, a computer model can be used to estimate how efficiently the water is being applied.

Table 8.2a. Percent irrigation water losses for different furrow irrigation systems. 509
Section 13, Item J.

Type of
irrigation
system
Distribution
system
Air
evaporation
Soil
evaporation
Canopy
evaporation
Deep
percolation
Surface
runoff
Overall
efficiency
Every row 1-5 <1.0 1--5 0.0 10-20 10-35 40-75
W/Surge
valve
1-5 <1.0 1-5 0.0 5-15 5-15 60-85
W/Reuse 1-5 1-2 1-5 0.0 10-20 0 55-90
Siphon
tube
5-10 1-2 1-5 0.0 15-25 15-25 40-75
Alternate
row
1-5 <0.5 1-5 0.0 5-15 10-20 60-85
Table 8.2b. Percent irrigation water losses for different Sprinkler Irrigation systems.

Type of
irrigation
system
Distribution
system
Air
evaporation
Soil
evaporation
Canopy
evaporation
Deep
percolation
Surface
runoff
Overall
efficiency
Handmove <1.0 3-5 1-5 10-15 5-10 0-5 60-80
Solid set <1.0 3-5 1-5 10-15 0-10 0-5 60-85
Traveler <1.0 1-3 1-5 1-5 0-5 5-10 55-75
High
pressure
impact
<0.5 1-3 0-1 1-5 0-5 0-5 70-80
Low
pressure
impact
<0.5 1-3 0-1 1-3 0.5 0-10 75-85
Low
pressure
spray
<0.5 1-3 0-1 1-3 0-5 0-20 70-90
Low
pressure
bubble
<0.5 0.0 0-0.5 0.0 0-5 20-40 60-95
Drip
irrigation
<0.5 0.0 0.0 0.0 5-30 0.0 70-95
510
Section 13, Item J.

Water Balance Model Results
Attachment F
511
Section 13, Item J.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (17) (16) (18) (19) (20) (21) (23) (24) Climate Values, inches Inflows, ac-ft Treatment Ponds Storage Pond 5 Golf Course Irrigation Rainfall Ref. ET
Base
City I&I
Town
Field
Runoff
COWRF
Backwash
AWA
Backwash CDCR ARSA Rainfall Evap.

Total
Inflow to
Pond 5 Rainfall Evap.

To/From
Storage
Net
Storage
Historical
Storage
Historical
Demand
Theoretical
Demand
Theoretical
Pond Losses
Total
Theoretical
Demand
Provided
by City
Total
Provided
Oct. 1.2 3.24 39.0 1.9 0.0 4.9 0.71 27.3 0.5 (1.5) 45.5 0.4 (1.1) 5.4 37.6 37.1 37.4 21.9 0.5 22.4 0.0 22.4 Nov. 2.8 1.68 37.8 4.6 0.0 0.0 0.52 0.0 1.3 (0.8) 43.5 1.0 (0.6) (6.1) 31.5 31.8 16.4 0.0 0.0 0.0 0.0 0.0 Dec. 3.5 1.21 39.0 5.8 0.0 0.0 0.52 0.0 1.7 (0.6) 46.4 1.2 (0.4) (2.8) 28.7 28.5 0.0 0.0 0.0 0.0 0.0 0.0 Jan. 5.1 1.48 39.0 8.4 3.5 0.0 0.37 0.0 2.4 (0.7) 53.0 1.8 (0.5) 4.2 33.0 33.5 0.0 0.0 0.0 0.0 0.0 0.0 Feb. 3.1 1.95 35.2 5.2 0.0 0.0 0.46 0.0 1.5 (0.9) 41.4 1.1 (0.7) 1.8 34.8 34.7 0.0 0.0 0.0 0.0 0.0 0.0 Mar. 3.2 3.02 39.0 5.2 0.0 0.0 0.37 0.0 1.5 (1.4) 44.7 1.1 (1.1) 0.7 35.5 35.3 0.0 0.0 0.0 0.0 0.0 0.0 Apr. 1.8 4.57 37.8 2.9 0.0 5.3 0.58 35.3 0.8 (2.2) 45.2 0.6 (1.6) 3.4 38.9 38.2 8.8 29.3 0.7 30.0 0.0 30.0 May 0.6 5.97 39.0 1.0 0.0 9.1 0.55 70.1 0.3 (2.8) 47.1 0.2 (2.1) (0.9) 38.0 38.3 54.9 59.6 1.4 61.0 0.0 61.0 Jun. 0.2 7.19 37.8 0.3 0.0 12.0 0.25 92.4 0.1 (3.4) 47.0 0.1 (2.5) (7.9) 30.1 30.4 71.8 78.6 1.8 80.4 0.0 80.4 Jul. 0.1 7.64 39.0 0.1 0.0 13.1 0.58 100.9 0.0 (3.6) 49.2 0.0 (2.7) (3.3) 26.8 26.9 83.4 85.8 2.0 87.8 0.0 87.8 Aug. 0.1 6.98 37.8 0.2 0.0 11.8 0.49 91.1 0.1 (3.3) 47.0 0.0 (2.4) 0.3 27.1 27.7 78.1 77.5 1.8 79.3 0.0 79.3 Sep. 0.3 4.99 39.0 0.5 0.0 11.0 0.43 64.6 0.2 (2.4) 48.7 0.1 (1.7) 4.4 32.2 32.2 62.4 52.4 1.2 53.6 0.0 53.6 Total, AFY 22.0 49.9 459 36.1 3.5 67.2 5.83 481.7 10.5 (23.7) 558.8 7.7 (17.5) (0.7) 413.2 405.1 9.4 414.5 0 414.5 Base City Flow 0.410 mgd
Town Field Runoff Calculation Parameters LAA Information Pond Information Storage Soil Interception, inches 3 1 2 3 4 5 6 7
Percent Infiltration, saturated soil 0.4 Surface Area, acres 1.5 1.2 1.0 2.0 4.2 3.9 5.3 Percent Infiltration, unsaturated soil 0.6 Area, acres 57 5.6 130 3.1 Storage Volume, ac-ft 41.7 25.2 25.8 Min 2-month Rainfall for Saturation, inches 10 Crop Coefficient 0.32 0.32 0.88 -- Feb.-May. Perc. Rate, in/d 0.0 0.0 Max Precip Before Runoff Capture, inches 20 Irr. Efficiency 0.80 0.80 0.84 -- Jun.-Jan. Perc. Rate, in/d 0.0 0.0 (1) Average year rainfall from Ione NCDC station (#044283) Legend for Cell Shading (2) Reference evapotranspiration from Plymouth CIMIS station (Station 227) - Value not directly used (3) = (Base City Flow) x (number of days in month) x 3.07 - Historical value used as reference (4) = 3.07 x (I&I in million gallons]. I&I in million gallons = 0.539 x (rainfall in inches) - 0.012, using linear equation developed in this TM. - Independent variable (manual input) (5) = (Column 1 - Column 2 - interception of 3 inches - infiltration in inches)/(12 inches per foot) x (surface area of Town Field, 57 acres). If Column 1 > 8 inches, then set value of Column 1 to 8 inches.

Infiltration in inches = (percent infiltration) x (Column 1 - Column 2 - interception of 3 inches). If the sum of Column 1 in the current and previous month >= 10 inches, percent infiltration is 0.4. Otherwise, percent infiltration is 0.6. (6) = (Column 9) x (Percentage of monthly COWRF influent flow discarded as backwash as defined in COGC TM) (see Attachment D) (7) Average monthly AWA backwash flow from 2021 to 2024 (8) = 0. Assume no CDCR flow.
(9) = Column 21 / (1 - COWRF filter backwash percentage as defined in COGC TM) (see Attachment D) (10) = (Column 1)/12 x (surface area of Ponds 1-4, 5.7 acres) (11) = (Column 2)/12 x (surface area of Ponds 1-4, 5.7 acres) (12) = Column 3 + Column 4 + Column 5 + Column 6 + Column 7 + Column 10 + Column 11 (13) = (Column 1)/12 x (surface area of Pond 5, 4.2 acres) (14) = (Column 2)/12 x (surface area of Pond 5, 4.2 acres) (15) = Column 12 + Column 13 + Column 14 - (Column 23 + Column 28 + Column 32 + Column 34) (16) = Column 16 of previous month + Column 15 of current month. If this is greater than the Pond 5 volume of 41.7 acre-feet, Column 16 is set to 41.7.

In August, Column 16 is set to 22.9 and the value in Column 34 is adjusted so that the formula in Column 15 predicts this value. (17) Monthly average storage volume in Pond 5 from 2019 to 2024 (18) Historical irrigation demand for COGC, from COGC TM (see Attachment D) (19) = [Column 1 - (Column 2 x crop coefficient of 0.88)]/12 x (surface area of golf course, 130 acres) x (irrigation efficiency of 0.84). If Column 19 < 0, then set Column 19 to 0. (20) = (Column 1 - Column 2)/12 x (surface area of golf course pond, 3.1 acres). If Column 20 < 0, then set Column 20 to 0. (21) = Column 19 + Column 20
(22) = Column 21 - Column 23
(23) = 0. Assume no flow from the City.
(24) = Column 22 + Column 23
414.5
Golf
Course
Pond
Treatment Percolation
Town
Field
City
Field
Golf
Course

87.8 79.3

53.6 30.0

61.0 80.4

0.0 0.0

0.0 22.4

0.0 0.0
Current Flows: Average Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 0.32 Month
(22)
Provided
by
Partners
988-50-24-10 1of16
City of Ione
Updated Water Balance
512
Section 13, Item J.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May
Jun.

Jul.

Aug.

Sep.

Total, AFY
Month
(25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (44) (45) (46) (47) (48) (49) Town Field Irrigation City Field Irrigation Percolation Pond 7 Avail for
Town
Historical
Demand
Theoretical
Demand
Provided
by City
Avail for
City
Historical
Demand
Theoretical
Demand
Provided
by City
System
Excess
Empty
Pond 5
Total
Flow to
Pond Rainfall Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Empty
Pond 7
Total
Flow to
Pond Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Check for
System
Overflow
Discharge/
Store
Elsewhere

77.0 4.3 4.0 4.0 73.0 0.3 0.4 0.4 0.0 35 35.0 0.5 (1.4) 0.0 (25.9) 0.0 60 60.0 (1.1) 0.0 (25.2) 0.0 OK 84.5

81.5 1.2 0.0 0.0 81.5 0.0 0.0 0.0 0.0 50 50.0 1.2 (0.7) 0.0 50.5 25.8 24.7 (0.5) 0.0 25.1 25.1 OK 0.0

78.7 0.0 0.0 0.0 78.7 0.0 0.0 0.0 0.0 50 50.0 1.6 (0.5) 0.0 51.0 25.8 51.0 (0.4) 0.0 (0.0) 25.0 OK 51.8

83.0 0.0 0.0 0.0 83.0 0.0 0.0 0.0 0.0 50 50.0 2.2 (0.7) 0.0 51.6 25.8 51.6 (0.5) 0.0 (0.0) 25.0 OK 52.8

74.8 0.0 0.0 0.0 74.8 0.0 0.0 0.0 0.0 40 40.0 1.4 (0.9) 0.0 40.5 25.8 40.5 (0.6) 0.0 0.0 25.0 OK 40.9

79.5 0.0 0.0 0.0 79.5 0.0 0.0 0.0 0.0 44 44.0 1.4 (1.3) 0.0 44.1 25.8 44.1 (1.0) 0.0 0.0 25.0 OK 44.1

79.8 1.8 5.4 5.4 74.4 0.0 0.5 0.5 0.0 35 35.0 0.8 (2.0) 0.0 33.8 25.8 33.8 (1.5) 0.0 0.0 25.1 OK 32.8

84.1 0.6 10.1 10.1 74.0 0.3 1.0 1.0 0.0 35 35.0 0.3 (2.6) 0.0 32.6 25.8 32.6 (1.9) 0.0 0.0 25.1 OK 30.9

82.6 15.4 13.2 13.2 69.4 1.2 1.3 1.3 0.0 38 38.0 0.1 (3.2) 0.0 34.9 25.8 34.9 (2.3) 0.0 (0.0) 25.1 OK 32.7

76.6 13.5 14.4 14.4 62.2 1.2 1.4 1.4 0.0 34 34.0 0.0 (3.4) 0.0 30.7 25.8 30.7 (2.5) 0.0 (0.0) 25.1 OK 28.2

71.4 21.2 13.0 13.0 58.4 1.8 1.3 1.3 0.0 30 30.0 0.1 (3.1) 0.0 27.0 25.8 27.0 (2.3) 0.0 0.0 25.1 OK 24.7

74.2 11.7 8.9 8.9 65.4 1.8 0.9 0.9 0.0 33 33.0 0.1 (2.2) 0.0 30.9 25.8 30.9 (1.6) 0.0 0.0 25.1 OK 29.4 943.1 69.7 69.0 69.0 874.2 6.8 6.8 6.8 0.0 474 474.0 9.7 (22.0) 0.0 401.7 60 462 (16.2) 0.0 (0.1) 453 Total Inflows: 474 Total Inflows: 462 Total Excess Water: 453 Total Outflows: 0 Total Outflows: 0
Legend for Cell Shading
(25) = (Column 16 of previous month) + Column 12 + Column 13 + Column 14 - Column 23. If Column 25 < 0, then set Column 25 to 0. - Value not directly used (26) Monthly average historical irrigation demand for Town Field from 2019 to 2024 - Historical value used as reference (27) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of Town Field, 57 acres) x (irrigation efficiency of 0.8). If Column 27 < 0, then set Column 27 to 0. - Independent variable (manual input) (28) If Column 25 < Column 27, Column 25. Otherwise, Column 27. (29) = Column 25 - Column 28. If Column 29 < 0, then set Column 29 to 0. (30) Monthly average historical irrigation demand for City Field from 2018 to 2023. (31) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of City Field, 5.6 acres) x (irrigation efficiency of 0.8). If Column 31 < 0, then set Column 31 to 0. (32) If Column 29 < Column 31, Column 29. Otherwise, Column 31. (33) = (Column 16 from previous month) + Column 15 - (Pond 5 volume, 41.7 acre-feet). If Column 33 < 0, then set Column 33 to 0. (34) Manually entered to move water between Pond 5 and Pond 7 to approximately match historical Pond 5 volumes. Positive values indicate flow from Pond 5 to Pond 7. Negative values indicate flow from Pond 7 to Town Field/City Field. (35) = Column 33 + Column 34
(36) = (Column 1)/12 x (surface area of Pond 7, 5.3 acres) (37) = (Column 2)/12 x (surface area of Pond 7, 5.3 acres) (38) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 7, 5.3 acres). Percolation rate set to 0 inches per day. (39) = Column 35 + Column 36 + Column 37 + Column 38 - Column 41 (40) = Column 40 of previous month + Column 39 of current month. If this is greater than the Pond 7 volume of 25.8 acre-feet, Column 40 is set to 25.8. If this is < 0, Column 40 is set to 0. In August, Column 40 must be <= 0 in order for the balance to work. (41) Manually entered to move water between Pond 7 and Pond 6. Positive values indicate flow from Pond 7 to Pond 6. Negative values indicate flow from Pond 6 to Pond 7. (42) If Column 40 >= Pond 7 volume of 25.8 acre-feet, Column 42 = (Column 40 of previous month) + Column 39 + Column 41 - 25.8. If Column 40 < 25.8, Column 42 = Column 41. (43) = (Column 1)/12 x (surface area of Pond 6,3.9 acres) (44) = (Column 2)/12 x (surface area of Pond 6, 3.9 acres) (45) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 6, 3.9 acres). Percolation rate set to 0 inches per day. (46) = Column 42 + Column 43 + Column 44 + Column 45
(47) = Column 47 of previous month + Column 46 of current month. If this is greater than the Pond 6 storage volume of 25.2 acre-feet, Column 47 is set to 25.2. If Column 47 < 0, set to 0. In July, Column 47 must be <= 0 in order for the balance to work. (48) If (Column 46 of current month) + (Column 47 of previous month) > Pond 6 storage volume of 25.2 acre-feet, Column 48 = "Overflow". Otherwise, Column 48 = "OK". (49) Manually entered to move water between Pond 6 and New Storage/Disposal Site to ensure pond storage capacity is not exceeded.

7.2 0.0

0.0 0.1

0.6 0.2

0.1 1.7

1.0 1.0

0.4 0.9

1.1 Current Flows: Average Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 0.32 (43)
Percolation Pond 6
Rainfall
988-50-24-10 2of16
City of Ione
Updated Water Balance
513
Section 13, Item J.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (17) (16) (18) (19) (20) (21) (23) (24) Climate Values, inches Inflows, ac-ft Treatment Ponds Storage Pond 5 Golf Course Irrigation Rainfall Ref. ET
Base
City I&I
Town
Field
Runoff
COWRF
Backwash
AWA
Backwash CDCR ARSA Rainfall Evap.

Total
Inflow to
Pond 5 Rainfall Evap.

To/From
Storage
Net
Storage
Historical
Storage
Historical
Demand
Theoretical
Demand
Theoretical
Pond Losses
Total
Theoretical
Demand
Provided
by City
Total
Provided
Oct. 1.2 3.24 39.0 1.9 0.0 4.9 0.71 27.3 0.5 (1.5) 45.5 0.4 (1.1) 5.2 37.4 37.1 37.4 21.9 0.5 22.4 0.0 22.4 Nov. 2.8 1.68 37.8 4.6 0.0 0.0 0.52 0.0 1.3 (0.8) 43.5 1.0 (0.6) (6.1) 31.2 31.8 16.4 0.0 0.0 0.0 0.0 0.0 Dec. 3.5 1.21 39.0 5.8 0.0 0.0 0.52 0.0 1.7 (0.6) 46.4 1.2 (0.4) (2.8) 28.4 28.5 0.0 0.0 0.0 0.0 0.0 0.0 Jan. 5.1 1.48 39.0 8.4 3.5 0.0 0.37 0.0 2.4 (0.7) 53.0 1.8 (0.5) 4.2 32.7 33.5 0.0 0.0 0.0 0.0 0.0 0.0 Feb. 3.1 1.95 35.2 5.2 0.0 0.0 0.46 0.0 1.5 (0.9) 41.4 1.1 (0.7) 1.8 34.5 34.7 0.0 0.0 0.0 0.0 0.0 0.0 Mar. 3.2 3.02 39.0 5.2 0.0 0.0 0.37 0.0 1.5 (1.4) 44.7 1.1 (1.1) 0.7 35.2 35.3 0.0 0.0 0.0 0.0 0.0 0.0 Apr. 1.8 4.57 37.8 2.9 0.0 5.3 0.58 35.3 0.8 (2.2) 45.2 0.6 (1.6) 2.9 38.1 38.2 8.8 29.3 0.7 30.0 0.0 30.0 May 0.6 5.97 39.0 1.0 0.0 9.1 0.55 70.1 0.3 (2.8) 47.1 0.2 (2.1) 0.4 38.5 38.3 54.9 59.6 1.4 61.0 0.0 61.0 Jun. 0.2 7.19 37.8 0.3 0.0 12.0 0.25 92.4 0.1 (3.4) 47.0 0.1 (2.5) (7.8) 30.7 30.4 71.8 78.6 1.8 80.4 0.0 80.4 Jul. 0.1 7.64 39.0 0.1 0.0 13.1 0.58 100.9 0.0 (3.6) 49.2 0.0 (2.7) (3.8) 26.9 26.9 83.4 85.8 2.0 87.8 0.0 87.8 Aug. 0.1 6.98 37.8 0.2 0.0 11.8 0.49 91.1 0.1 (3.3) 47.0 0.0 (2.4) (0.0) 26.9 27.7 78.1 77.5 1.8 79.3 0.0 79.3 Sep. 0.3 4.99 39.0 0.5 0.0 11.0 0.43 64.6 0.2 (2.4) 48.7 0.1 (1.7) 4.7 32.2 32.2 62.4 52.4 1.2 53.6 0.0 53.6 Total, AFY 22.0 49.9 459 36.1 3.5 67.2 5.83 481.7 10.5 (23.7) 558.8 7.7 (17.5) (0.6) 413.2 405.1 9.4 414.5 0 414.5 Base City Flow 0.410 mgd
Town Field Runoff Calculation Parameters LAA Information Pond Information Storage Soil Interception, inches 3 1 2 3 4 5 6 7
Percent Infiltration, saturated soil 0.4 Surface Area, acres 1.5 1.2 1.0 2.0 4.2 3.9 5.3 Percent Infiltration, unsaturated soil 0.6 Area, acres 57 5.6 130 3.1 Storage Volume, ac-ft 41.7 25.2 25.8 Min 2-month Rainfall for Saturation, inches 10 Crop Coefficient 1.00 1.00 0.88 -- Feb.-May. Perc. Rate, in/d 0.0 0.0 Max Precip Before Runoff Capture, inches 20 Irr. Efficiency 0.80 0.80 0.84 -- Jun.-Jan. Perc. Rate, in/d 0.0 0.0 (1) Average year rainfall from Ione NCDC station (#044283) Legend for Cell Shading (2) Reference evapotranspiration from Plymouth CIMIS station (Station 227) - Value not directly used (3) = (Base City Flow) x (number of days in month) x 3.07 - Historical value used as reference (4) = 3.07 x (I&I in million gallons]. I&I in million gallons = 0.539 x (rainfall in inches) - 0.012, using linear equation developed in this TM. - Independent variable (manual input) (5) = (Column 1 - Column 2 - interception of 3 inches - infiltration in inches)/(12 inches per foot) x (surface area of Town Field, 57 acres). If Column 1 > 8 inches, then set value of Column 1 to 8 inches.

Infiltration in inches = (percent infiltration) x (Column 1 - Column 2 - interception of 3 inches). If the sum of Column 1 in the current and previous month >= 10 inches, percent infiltration is 0.4. Otherwise, percent infiltration is 0.6. (6) = (Column 9) x (Percentage of monthly COWRF influent flow discarded as backwash as defined in COGC TM) (see Attachment D) (7) Average monthly AWA backwash flow from 2021 to 2024 (8) = 0. Assume no CDCR flow.
(9) = Column 21 / (1 - COWRF filter backwash percentage as defined in COGC TM) (see Attachment D) (10) = (Column 1)/12 x (surface area of Ponds 1-4, 5.7 acres) (11) = (Column 2)/12 x (surface area of Ponds 1-4, 5.7 acres) (12) = Column 3 + Column 4 + Column 5 + Column 6 + Column 7 + Column 10 + Column 11 (13) = (Column 1)/12 x (surface area of Pond 5, 4.2 acres) (14) = (Column 2)/12 x (surface area of Pond 5, 4.2 acres) (15) = Column 12 + Column 13 + Column 14 - (Column 23 + Column 28 + Column 32 + Column 34) (16) = Column 16 of previous month + Column 15 of current month. If this is greater than the Pond 5 volume of 41.7 acre-feet, Column 16 is set to 41.7.

In September, Column 16 is set to 0 and the value in Column 34 is adjusted so that the formula in Column 15 predicts this value. (17) Monthly average storage volume in Pond 5 from 2019 to 2024 (18) Historical irrigation demand for COGC, from COGC TM (see Attachment D) (19) = [Column 1 - (Column 2 x crop coefficient of 0.88)]/12 x (surface area of golf course, 130 acres) x (irrigation efficiency of 0.84). If Column 19 < 0, then set Column 19 to 0. (20) = (Column 1 - Column 2)/12 x (surface area of golf course pond, 3.1 acres). If Column 20 < 0, then set Column 20 to 0. (21) = Column 19 + Column 20
(22) = Column 21 - Column 23
(23) = 0. Assume no flow from the City.
(24) = Column 22 + Column 23
414.5
Golf
Course
Pond
Treatment Percolation
Town
Field
City
Field
Golf
Course

87.8 79.3

53.6 30.0

61.0 80.4

0.0 0.0

0.0 22.4

0.0 0.0
Current Flows: Average Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 1 Month
(22)
Provided
by
Partners
988-50-24-10 3of16
City of Ione
Updated Water Balance
514
Section 13, Item J.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May
Jun.

Jul.

Aug.

Sep.

Total, AFY
Month
(25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (44) (45) (46) (47) (48) (49) Town Field Irrigation City Field Irrigation Percolation Pond 7 Avail for
Town
Historical
Demand
Theoretical
Demand
Provided
by City
Avail for
City
Historical
Demand
Theoretical
Demand
Provided
by City
System
Excess
Empty
Pond 5
Total
Flow to
Pond Rainfall Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Empty
Pond 7
Total
Flow to
Pond Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Check for
System
Overflow
Discharge/St
ore
Elsewhere

77.0 4.3 12.4 12.4 64.6 0.3 1.2 1.2 0.0 26 26.0 0.5 (1.4) 0.0 (25.9) 0.0 51 51.0 (1.1) 0.0 (23.9) 0.0 OK 74.2

81.2 1.2 0.0 0.0 81.2 0.0 0.0 0.0 0.0 50 50.0 1.2 (0.7) 0.0 50.5 25.8 24.7 (0.5) 0.0 25.1 25.1 OK 0.0

78.4 0.0 0.0 0.0 78.4 0.0 0.0 0.0 0.0 50 50.0 1.6 (0.5) 0.0 51.0 25.8 51.0 (0.4) 0.0 0.1 25.1 OK 51.7

82.7 0.0 0.0 0.0 82.7 0.0 0.0 0.0 0.0 50 50.0 2.2 (0.7) 0.0 51.6 25.8 51.6 (0.5) 0.0 (0.0) 25.1 OK 52.8

74.5 0.0 0.0 0.0 74.5 0.0 0.0 0.0 0.0 40 40.0 1.4 (0.9) 0.0 40.5 25.8 40.5 (0.6) 0.0 0.0 25.1 OK 40.9

79.2 0.0 0.0 0.0 79.2 0.0 0.0 0.0 0.0 44 44.0 1.4 (1.3) 0.0 44.1 25.8 44.1 (1.0) 0.0 0.0 25.1 OK 44.1

79.5 1.8 16.7 16.7 62.7 0.0 1.6 1.6 0.0 23 23.0 0.8 (2.0) 0.0 21.8 25.8 21.8 (1.5) 0.0 0.0 25.2 OK 20.8

83.3 0.6 31.7 31.7 51.6 0.3 3.1 3.1 0.0 10 10.0 0.3 (2.6) 0.0 7.6 25.8 7.6 (1.9) 0.0 0.0 25.2 OK 5.9

83.1 15.4 41.3 41.3 41.8 1.2 4.1 4.1 0.0 7 7.0 0.1 (3.2) 0.0 3.9 25.8 3.9 (2.3) 0.0 (0.0) 25.2 OK 1.7

77.3 13.5 44.9 44.9 32.3 1.2 4.4 4.4 0.0 1 1.0 0.0 (3.4) 0.0 (2.3) 23.5 0.0 (2.5) 0.0 (2.5) 22.7 OK 0.0

71.6 21.2 40.7 40.7 30.9 1.8 4.0 4.0 0.0 0 0.0 0.1 (3.1) 0.0 (3.0) 20.4 0.0 (2.3) 0.0 (2.2) 20.5 OK 0.0

74.0 11.7 27.7 27.7 46.3 1.8 2.7 2.7 0.0 12 12.0 0.1 (2.2) 0.0 9.9 25.8 4.6 (1.6) 0.0 3.1 23.5 OK 0.0 941.9 69.7 215.5 215.5 726.4 6.8 21.2 21.2 0.0 313 313.0 9.7 (22.0) 0.0 249.7 51 301 (16.2) 0.0 (0.4) 292 Total Inflows: 313 Total Inflows: 301 Total Excess Water: 292 Total Outflows: 0 Total Outflows: 0
Legend for Cell Shading
(25) = (Column 16 of previous month) + Column 12 + Column 13 + Column 14 - Column 23. If Column 25 < 0, then set Column 25 to 0. - Value not directly used (26) Monthly average historical irrigation demand for Town Field from 2019 to 2024 - Historical value used as reference (27) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of Town Field, 57 acres) x (irrigation efficiency of 0.8). If Column 27 < 0, then set Column 27 to 0. - Independent variable (manual input) (28) If Column 25 < Column 27, Column 25. Otherwise, Column 27. (29) = Column 25 - Column 28. If Column 29 < 0, then set Column 29 to 0. (30) Monthly average historical irrigation demand for City Field from 2018 to 2023. (31) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of City Field, 5.6 acres) x (irrigation efficiency of 0.8). If Column 31 < 0, then set Column 31 to 0. (32) If Column 29 < Column 31, Column 29. Otherwise, Column 31. (33) = (Column 16 from previous month) + Column 15 - (Pond 5 volume, 41.7 acre-feet). If Column 33 < 0, then set Column 33 to 0. (34) Manually entered to move water between Pond 5 and Pond 7 to approximately match historical Pond 5 volumes. Positive values indicate flow from Pond 5 to Pond 7. Negative values indicate flow from Pond 7 to Town Field/City Field. (35) = Column 33 + Column 34
(36) = (Column 1)/12 x (surface area of Pond 7, 5.3 acres) (37) = (Column 2)/12 x (surface area of Pond 7, 5.3 acres) (38) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 7, 5.3 acres). Percolation rate set to 0 inches per day. (39) = Column 35 + Column 36 + Column 37 + Column 38 - Column 41 (40) = Column 40 of previous month + Column 39 of current month. If this is greater than the Pond 7 volume of 25.8 acre-feet, Column 40 is set to 25.8. If this is < 0, Column 40 is set to 0. In August, Column 40 must be <= 0 in order for the balance to work. (41) Manually entered to move water between Pond 7 and Pond 6. Positive values indicate flow from Pond 7 to Pond 6. Negative values indicate flow from Pond 6 to Pond 7. (42) If Column 40 >= Pond 7 volume of 25.8 acre-feet, Column 42 = (Column 40 of previous month) + Column 39 + Column 41 - 25.8. If Column 40 < 25.8, Column 42 = Column 41. (43) = (Column 1)/12 x (surface area of Pond 6,3.9 acres) (44) = (Column 2)/12 x (surface area of Pond 6, 3.9 acres) (45) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 6, 3.9 acres). Percolation rate set to 0 inches per day. (46) = Column 42 + Column 43 + Column 44 + Column 45
(47) = Column 47 of previous month + Column 46 of current month. If this is greater than the Pond 6 storage volume of 25.2 acre-feet, Column 47 is set to 25.2. If Column 47 < 0, set to 0. In July, Column 47 must be <= 0 in order for the balance to work. (48) If (Column 46 of current month) + (Column 47 of previous month) > Pond 6 storage volume of 25.2 acre-feet, Column 48 = "Overflow". Otherwise, Column 48 = "OK". (49) Manually entered to move water between Pond 6 and New Storage/Disposal Site to ensure pond storage capacity is not exceeded.

7.2 0.0

0.0 0.1

0.6 0.2

0.1 1.7

1.0 1.0

0.4 0.9

1.1 Current Flows: Average Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 1 (43)
Percolation Pond 6
Rainfall
988-50-24-10 4of16
City of Ione
Updated Water Balance
515
Section 13, Item J.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (17) (16) (18) (19) (20) (21) (23) (24) Climate Values, inches Inflows, ac-ft Treatment Ponds Storage Pond 5 Golf Course Irrigation Rainfall Ref. ET
Base
City I&I
Town
Field
Runoff
COWRF
Backwash
AWA
Backwash CDCR ARSA Rainfall Evap.

Total
Inflow to
Pond 5 Rainfall Evap.

To/From
Storage
Net
Storage
Historical
Storage
Historical
Demand
Theoretical
Demand
Theoretical
Pond Losses
Total
Theoretical
Demand
Provided
by City
Total
Provided
Oct. 2.2 3.24 39.0 3.5 0.0 2.0 0.71 11.3 1.0 (1.5) 44.7 0.8 (1.1) 5.0 37.2 37.1 37.4 9.0 0.3 9.3 0.0 9.3 Nov. 5.2 1.68 37.8 8.6 3.3 0.0 0.52 0.0 2.5 (0.8) 51.9 1.8 (0.6) (5.8) 31.4 31.8 16.4 0.0 0.0 0.0 0.0 0.0 Dec. 6.6 1.21 39.0 10.8 20.7 0.0 0.52 0.0 3.1 (0.6) 73.6 2.3 (0.4) (2.5) 28.8 28.5 0.0 0.0 0.0 0.0 0.0 0.0 Jan. 9.5 1.48 39.0 15.7 43.7 0.0 0.37 0.0 4.5 (0.7) 102.6 3.3 (0.5) 4.4 33.2 33.5 0.0 0.0 0.0 0.0 0.0 0.0 Feb. 5.9 1.95 35.2 9.7 8.0 0.0 0.46 0.0 2.8 (0.9) 55.2 2.1 (0.7) 1.6 34.8 34.7 0.0 0.0 0.0 0.0 0.0 0.0 Mar. 6.0 3.02 39.0 9.8 0.0 0.0 0.37 0.0 2.8 (1.4) 50.6 2.1 (1.1) 0.6 35.4 35.3 0.0 0.0 0.0 0.0 0.0 0.0 Apr. 3.3 4.57 37.8 5.4 0.0 1.8 0.58 11.9 1.5 (2.2) 45.0 1.1 (1.6) 2.8 38.2 38.2 8.8 9.8 0.3 10.1 0.0 10.1 May 1.2 5.97 39.0 1.9 0.0 8.0 0.55 61.7 0.6 (2.8) 47.2 0.4 (2.1) 0.5 38.7 38.3 54.9 52.5 1.2 53.7 0.0 53.7 Jun. 0.4 7.19 37.8 0.7 0.0 11.6 0.25 89.4 0.2 (3.4) 47.1 0.2 (2.5) (8.3) 30.3 30.4 71.8 76.1 1.7 77.8 0.0 77.8 Jul. 0.1 7.64 39.0 0.2 0.0 13.0 0.58 99.9 0.1 (3.6) 49.2 0.0 (2.7) (4.1) 26.2 26.9 83.4 85.0 1.9 86.9 0.0 86.9 Aug. 0.2 6.98 37.8 0.4 0.0 11.6 0.49 89.4 0.1 (3.3) 47.1 0.1 (2.4) 1.7 27.9 27.7 78.1 76.1 1.7 77.8 0.0 77.8 Sep. 0.6 4.99 39.0 1.0 0.0 10.2 0.43 59.9 0.3 (2.4) 48.6 0.2 (1.7) (4.1) 32.2 32.2 62.4 48.6 1.1 49.7 0.0 49.7 Total, AFY 41.1 49.9 459 67.7 75.7 58.2 5.83 423.5 19.5 (23.7) 662.7 14.4 (17.5) (8.4) 413.2 357.1 8.2 365.3 0 365.3 Base City Flow 0.410 mgd
Town Field Runoff Calculation Parameters LAA Information Pond Information Storage Soil Interception, inches 3 1 2 3 4 5 6 7
Percent Infiltration, saturated soil 0.4 Surface Area, acres 1.5 1.2 1.0 2.0 4.2 3.9 5.3 Percent Infiltration, unsaturated soil 0.6 Area, acres 57 5.6 130 3.1 Storage Volume, ac-ft 41.7 25.2 25.8 Min 2-month Rainfall for Saturation, inches 10 Crop Coefficient 0.32 0.32 0.88 -- Feb.-May. Perc. Rate, in/d 0.0 0.0 Max Precip Before Runoff Capture, inches 20 Irr. Efficiency 0.80 0.80 0.84 -- Jun.-Jan. Perc. Rate, in/d 0.0 0.0 (1) 1-in-100 year rainfall from Ione NCDC station (#044283) Legend for Cell Shading (2) Reference evapotranspiration from Plymouth CIMIS station (Station 227) - Value not directly used (3) = (Base City Flow) x (number of days in month) x 3.07 - Historical value used as reference (4) = 3.07 x (I&I in million gallons]. I&I in million gallons = 0.539 x (rainfall in inches) - 0.012, using linear equation developed in this TM. - Independent variable (manual input) (5) = (Column 1 - Column 2 - interception of 3 inches - infiltration in inches)/(12 inches per foot) x (surface area of Town Field, 57 acres). If Column 1 > 8 inches, then set value of Column 1 to 8 inches.

Infiltration in inches = (percent infiltration) x (Column 1 - Column 2 - interception of 3 inches). If the sum of Column 1 in the current and previous month >= 10 inches, percent infiltration is 0.4. Otherwise, percent infiltration is 0.6. (6) = (Column 9) x (Percentage of monthly COWRF influent flow discarded as backwash as defined in COGC TM) (see Attachment D) (7) Average monthly AWA backwash flow from 2021 to 2024 (8) = 0. Assume no CDCR flow.
(9) = Column 21 / (1 - COWRF filter backwash percentage as defined in COGC TM) (see Attachment D) (10) = (Column 1)/12 x (surface area of Ponds 1-4, 5.7 acres) (11) = (Column 2)/12 x (surface area of Ponds 1-4, 5.7 acres) (12) = Column 3 + Column 4 + Column 5 + Column 6 + Column 7 + Column 10 + Column 11 (13) = (Column 1)/12 x (surface area of Pond 5, 4.2 acres) (14) = (Column 2)/12 x (surface area of Pond 5, 4.2 acres) (15) = Column 12 + Column 13 + Column 14 - (Column 23 + Column 28 + Column 32 + Column 34) (16) = Column 16 of previous month + Column 15 of current month. If this is greater than the Pond 5 volume of 41.7 acre-feet, Column 16 is set to 41.7.

In August, Column 16 is set to 21.2 and the value in Column 34 is adjusted so that the formula in Column 15 predicts this value. (17) Monthly average storage volume in Pond 5 from 2019 to 2024 (18) Historical irrigation demand for COGC, from COGC TM (see Attachment D) (19) = [Column 1 - (Column 2 x crop coefficient of 0.88)]/12 x (surface area of golf course, 130 acres) x (irrigation efficiency of 0.84). If Column 19 < 0, then set Column 19 to 0. (20) = (Column 1 - Column 2)/12 x (surface area of golf course pond, 3.1 acres). If Column 20 < 0, then set Column 20 to 0. (21) = Column 19 + Column 20
(22) = Column 21 - Column 23
(23) = 0. Assume no flow from the City.
(24) = Column 22 + Column 23
365.3
Golf
Course
Pond
Treatment Percolation
Town
Field
City
Field
Golf
Course

86.9 77.8

49.7 10.1

53.7 77.8

0.0 0.0

0.0 9.3

0.0 0.0
Current Flows: 1-in-100 Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 0.32 Month
(22)
Provided
by
Partners
988-50-24-10 5of16
City of Ione
Updated Water Balance
516
Section 13, Item J.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May
Jun.

Jul.

Aug.

Sep.

Total, AFY
Month
(25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (44) (45) (46) (47) (48) (49) Town Field Irrigation City Field Irrigation Percolation Pond 7 Avail for
Town
Historical
Demand
Theoretical
Demand
Provided
by City
Avail for
City
Historical
Demand
Theoretical
Demand
Provided
by City
System
Excess
Empty
Pond 5
Total
Flow to
Pond Rainfall Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Empty
Pond 7
Total
Flow to
Pond Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Check for
System
Overflow
Discharge/
Store
Elsewhere

76.5 4.3 2.1 2.1 74.4 0.3 0.2 0.2 0.0 37 37.0 0.9 (1.4) 0.0 (26.5) 0.0 63 63.0 (1.1) 0.0 (25.3) 0.0 OK 87.9

90.4 1.2 0.0 0.0 90.4 0.0 0.0 0.0 0.0 59 59.0 2.3 (0.7) 0.0 60.6 25.8 34.8 (0.5) 0.0 25.1 25.1 OK 10.8 106.8 0.0 0.0 0.0 106.8 0.0 0.0 0.0 0.0 78 78.0 2.9 (0.5) 0.0 80.4 25.8 80.4 (0.4) 0.0 0.0 25.1 OK 82.1 134.2 0.0 0.0 0.0 134.2 0.0 0.0 0.0 0.0 101 101.0 4.2 (0.7) 0.0 104.5 25.8 104.5 (0.5) 0.0 0.0 25.2 OK 107.1

89.8 0.0 0.0 0.0 89.8 0.0 0.0 0.0 0.0 55 55.0 2.6 (0.9) 0.0 56.7 25.8 56.7 (0.6) 0.0 (0.0) 25.2 OK 58.0

86.4 0.0 0.0 0.0 86.4 0.0 0.0 0.0 0.0 51 51.0 2.6 (1.3) 0.0 52.3 25.8 52.3 (1.0) 0.0 (0.1) 25.1 OK 53.3

79.9 1.8 2.5 2.5 77.4 0.0 0.2 0.2 0.0 39 39.0 1.4 (2.0) 0.0 38.4 25.8 38.4 (1.5) 0.0 (0.0) 25.1 OK 38.0

83.7 0.6 9.1 9.1 74.5 0.3 0.9 0.9 0.0 35 35.0 0.5 (2.6) 0.0 32.9 25.8 32.9 (1.9) 0.0 0.0 25.1 OK 31.3

83.4 15.4 12.8 12.8 70.6 1.2 1.3 1.3 0.0 39 39.0 0.2 (3.2) 0.0 36.0 25.8 36.0 (2.3) 0.0 0.0 25.2 OK 33.8

76.9 13.5 14.3 14.3 62.6 1.2 1.4 1.4 0.0 35 35.0 0.1 (3.4) 0.0 31.7 25.8 31.7 (2.5) 0.0 (0.1) 25.1 OK 29.3

71.0 21.2 12.8 12.8 58.2 1.8 1.3 1.3 0.0 29 29.0 0.1 (3.1) 0.0 26.0 25.8 26.0 (2.3) 0.0 0.0 25.1 OK 23.8

74.9 11.7 8.3 8.3 66.6 1.8 0.8 0.8 0.0 42 42.0 0.3 (2.2) 0.0 40.1 25.8 40.1 (1.6) 0.0 0.0 25.2 OK 38.6 1053.9 69.7 61.9 61.9 992.0 6.8 6.1 6.1 0.0 600 600.0 18.2 (22.0) 0.0 533.1 63 597 (16.2) 0.0 (0.1) 594 Total Inflows: 600 Total Inflows: 597 Total Excess Water: 594 Total Outflows: 0 Total Outflows: 0
Legend for Cell Shading
(25) = (Column 16 of previous month) + Column 12 + Column 13 + Column 14 - Column 23. If Column 25 < 0, then set Column 25 to 0. - Value not directly used (26) Monthly average historical irrigation demand for Town Field from 2019 to 2024 - Historical value used as reference (27) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of Town Field, 57 acres) x (irrigation efficiency of 0.8). If Column 27 < 0, then set Column 27 to 0. - Independent variable (manual input) (28) If Column 25 < Column 27, Column 25. Otherwise, Column 27. (29) = Column 25 - Column 28. If Column 29 < 0, then set Column 29 to 0. (30) Monthly average historical irrigation demand for City Field from 2018 to 2023. (31) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of City Field, 5.6 acres) x (irrigation efficiency of 0.8). If Column 31 < 0, then set Column 31 to 0. (32) If Column 29 < Column 31, Column 29. Otherwise, Column 31. (33) = (Column 16 from previous month) + Column 15 - (Pond 5 volume, 41.7 acre-feet). If Column 33 < 0, then set Column 33 to 0. (34) Manually entered to move water between Pond 5 and Pond 7 to approximately match historical Pond 5 volumes. Positive values indicate flow from Pond 5 to Pond 7. Negative values indicate flow from Pond 7 to Town Field/City Field. (35) = Column 33 + Column 34
(36) = (Column 1)/12 x (surface area of Pond 7, 5.3 acres) (37) = (Column 2)/12 x (surface area of Pond 7, 5.3 acres) (38) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 7, 5.3 acres). Percolation rate set to 0 inches per day. (39) = Column 35 + Column 36 + Column 37 + Column 38 - Column 41 (40) = Column 40 of previous month + Column 39 of current month. If this is greater than the Pond 7 volume of 25.8 acre-feet, Column 40 is set to 25.8. If this is < 0, Column 40 is set to 0. In August, Column 40 must be <= 0 in order for the balance to work. (41) Manually entered to move water between Pond 7 and Pond 6. Positive values indicate flow from Pond 7 to Pond 6. Negative values indicate flow from Pond 6 to Pond 7. (42) If Column 40 >= Pond 7 volume of 25.8 acre-feet, Column 42 = (Column 40 of previous month) + Column 39 + Column 41 - 25.8. If Column 40 < 25.8, Column 42 = Column 41. (43) = (Column 1)/12 x (surface area of Pond 6,3.9 acres) (44) = (Column 2)/12 x (surface area of Pond 6, 3.9 acres) (45) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 6, 3.9 acres). Percolation rate set to 0 inches per day. (46) = Column 42 + Column 43 + Column 44 + Column 45
(47) = Column 47 of previous month + Column 46 of current month. If this is greater than the Pond 6 storage volume of 25.2 acre-feet, Column 47 is set to 25.2. If Column 47 < 0, set to 0. In July, Column 47 must be <= 0 in order for the balance to work. (48) If (Column 46 of current month) + (Column 47 of previous month) > Pond 6 storage volume of 25.2 acre-feet, Column 48 = "Overflow". Otherwise, Column 48 = "OK". (49) Manually entered to move water between Pond 6 and New Storage/Disposal Site to ensure pond storage capacity is not exceeded.

13.4 0.0

0.1 0.2

1.1 0.4

0.1 3.1

1.9 1.9

0.7 1.7

2.1 Current Flows: 1-in-100 Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 0.32 (43)
Percolation Pond 6
Rainfall
988-50-24-10 6of16
City of Ione
Updated Water Balance
517
Section 13, Item J.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (17) (16) (18) (19) (20) (21) (23) (24) Climate Values, inches Inflows, ac-ft Treatment Ponds Storage Pond 5 Golf Course Irrigation Rainfall Ref. ET
Base
City I&I
Town
Field
Runoff
COWRF
Backwash
AWA
Backwash CDCR ARSA Rainfall Evap.

Total
Inflow to
Pond 5 Rainfall Evap.

To/From
Storage
Net
Storage
Historical
Storage
Historical
Demand
Theoretical
Demand
Theoretical
Pond Losses
Total
Theoretical
Demand
Provided
by City
Total
Provided
Oct. 2.2 3.24 39.0 3.5 0.0 2.0 0.71 11.3 1.0 (1.5) 44.7 0.8 (1.1) 5.2 37.4 37.1 37.4 9.0 0.3 9.3 0.0 9.3 Nov. 5.2 1.68 37.8 8.6 3.3 0.0 0.52 0.0 2.5 (0.8) 51.9 1.8 (0.6) (5.8) 31.6 31.8 16.4 0.0 0.0 0.0 0.0 0.0 Dec. 6.6 1.21 39.0 10.8 20.7 0.0 0.52 0.0 3.1 (0.6) 73.6 2.3 (0.4) (2.5) 29.0 28.5 0.0 0.0 0.0 0.0 0.0 0.0 Jan. 9.5 1.48 39.0 15.7 43.7 0.0 0.37 0.0 4.5 (0.7) 102.6 3.3 (0.5) 4.4 33.4 33.5 0.0 0.0 0.0 0.0 0.0 0.0 Feb. 5.9 1.95 35.2 9.7 8.0 0.0 0.46 0.0 2.8 (0.9) 55.2 2.1 (0.7) 1.6 35.0 34.7 0.0 0.0 0.0 0.0 0.0 0.0 Mar. 6.0 3.02 39.0 9.8 0.0 0.0 0.37 0.0 2.8 (1.4) 50.6 2.1 (1.1) 0.6 35.6 35.3 0.0 0.0 0.0 0.0 0.0 0.0 Apr. 3.3 4.57 37.8 5.4 0.0 1.8 0.58 11.9 1.5 (2.2) 45.0 1.1 (1.6) 3.0 38.5 38.2 8.8 9.8 0.3 10.1 0.0 10.1 May 1.2 5.97 39.0 1.9 0.0 8.0 0.55 61.7 0.6 (2.8) 47.2 0.4 (2.1) 0.3 38.8 38.3 54.9 52.5 1.2 53.7 0.0 53.7 Jun. 0.4 7.19 37.8 0.7 0.0 11.6 0.25 89.4 0.2 (3.4) 47.1 0.2 (2.5) (8.3) 30.5 30.4 71.8 76.1 1.7 77.8 0.0 77.8 Jul. 0.1 7.64 39.0 0.2 0.0 13.0 0.58 99.9 0.1 (3.6) 49.2 0.0 (2.7) (4.4) 26.1 26.9 83.4 85.0 1.9 86.9 0.0 86.9 Aug. 0.2 6.98 37.8 0.4 0.0 11.6 0.49 89.4 0.1 (3.3) 47.1 0.1 (2.4) 0.8 26.9 27.7 78.1 76.1 1.7 77.8 0.0 77.8 Sep. 0.6 4.99 39.0 1.0 0.0 10.2 0.43 59.9 0.3 (2.4) 48.6 0.2 (1.7) (4.5) 32.2 32.2 62.4 48.6 1.1 49.7 0.0 49.7 Total, AFY 41.1 49.9 459 67.7 75.7 58.2 5.83 423.5 19.5 (23.7) 662.7 14.4 (17.5) 413.2 357.1 8.2 365.3 0 365.3 Base City Flow 0.410 mgd
Town Field Runoff Calculation Parameters LAA Information Pond Information Storage Soil Interception, inches 3 1 2 3 4 5 6 7
Percent Infiltration, saturated soil 0.4 Surface Area, acres 1.5 1.2 1.0 2.0 4.2 3.9 5.3 Percent Infiltration, unsaturated soil 0.6 Area, acres 57 5.6 130 3.1 Storage Volume, ac-ft 41.7 25.2 25.8 Min 2-month Rainfall for Saturation, inches 10 Crop Coefficient 1.00 1.00 0.88 -- Feb.-May. Perc. Rate, in/d 0.0 0.0 Max Precip Before Runoff Capture, inches 20 Irr. Efficiency 0.80 0.80 0.84 -- Jun.-Jan. Perc. Rate, in/d 0.0 0.0 (1) 1-in-100 year rainfall from Ione NCDC station (#044283) Legend for Cell Shading (2) Reference evapotranspiration from Plymouth CIMIS station (Station 227) - Value not directly used (3) = (Base City Flow) x (number of days in month) x 3.07 - Historical value used as reference (4) = 3.07 x (I&I in million gallons]. I&I in million gallons = 0.539 x (rainfall in inches) - 0.012, using linear equation developed in this TM. - Independent variable (manual input) (5) = (Column 1 - Column 2 - interception of 3 inches - infiltration in inches)/(12 inches per foot) x (surface area of Town Field, 57 acres). If Column 1 > 8 inches, then set value of Column 1 to 8 inches.

Infiltration in inches = (percent infiltration) x (Column 1 - Column 2 - interception of 3 inches). If the sum of Column 1 in the current and previous month >= 10 inches, percent infiltration is 0.4. Otherwise, percent infiltration is 0.6. (6) = (Column 9) x (Percentage of monthly COWRF influent flow discarded as backwash as defined in COGC TM) (see Attachment D) (7) Average monthly AWA backwash flow from 2021 to 2024 (8) = 0. Assume no CDCR flow.
(9) = Column 21 / (1 - COWRF filter backwash percentage as defined in COGC TM) (see Attachment D) (10) = (Column 1)/12 x (surface area of Ponds 1-4, 5.7 acres) (11) = (Column 2)/12 x (surface area of Ponds 1-4, 5.7 acres) (12) = Column 3 + Column 4 + Column 5 + Column 6 + Column 7 + Column 10 + Column 11 (13) = (Column 1)/12 x (surface area of Pond 5, 4.2 acres) (14) = (Column 2)/12 x (surface area of Pond 5, 4.2 acres) (15) = Column 12 + Column 13 + Column 14 - (Column 23 + Column 28 + Column 32 + Column 34) (16) = Column 16 of previous month + Column 15 of current month. If this is greater than the Pond 5 volume of 41.7 acre-feet, Column 16 is set to 41.7.

In September, Column 16 is set to 0 and the value in Column 34 is adjusted so that the formula in Column 15 predicts this value. (17) Monthly average storage volume in Pond 5 from 2019 to 2024 (18) Historical irrigation demand for COGC, from COGC TM (see Attachment D) (19) = [Column 1 - (Column 2 x crop coefficient of 0.88)]/12 x (surface area of golf course, 130 acres) x (irrigation efficiency of 0.84). If Column 19 < 0, then set Column 19 to 0. (20) = (Column 1 - Column 2)/12 x (surface area of golf course pond, 3.1 acres). If Column 20 < 0, then set Column 20 to 0. (21) = Column 19 + Column 20
(22) = Column 21 - Column 23
(23) = 0. Assume no flow from the City.
(24) = Column 22 + Column 23
365.3
Golf
Course
Pond
Treatment Percolation
Town
Field
City
Field
Golf
Course

86.9 77.8

49.7 10.1

53.7 77.8

0.0 0.0

0.0 9.3

0.0 0.0
Current Flows: 1-in-100 Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 1 Month
(22)
Provided
by
Partners
988-50-24-10 7of16
City of Ione
Updated Water Balance
518
Section 13, Item J.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May
Jun.

Jul.

Aug.

Sep.

Total, AFY
Month
(25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (44) (45) (46) (47) (48) (49) Town Field Irrigation City Field Irrigation Percolation Pond 7 Avail for
Town
Historical
Demand
Theoretical
Demand
Provided
by City
Avail for
City
Historical
Demand
Theoretical
Demand
Provided
by City
System
Excess
Empty
Pond 5
Total
Flow to
Pond Rainfall Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Empty
Pond 7
Total
Flow to
Pond Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Check for
System
Overflow
Discharge/
Store
Elsewhere

76.5 4.3 6.5 6.5 70.0 0.3 0.6 0.6 0.0 32 32.0 0.9 (1.4) 0.0 (26.5) 0.0 58 58.0 (1.1) 0.0 (25.4) 0.0 OK 83.0

90.6 1.2 0.0 0.0 90.6 0.0 0.0 0.0 0.0 59 59.0 2.3 (0.7) 0.0 60.6 25.8 34.8 (0.5) 0.0 25.1 25.1 OK 10.8 107.0 0.0 0.0 0.0 107.0 0.0 0.0 0.0 0.0 78 78.0 2.9 (0.5) 0.0 80.4 25.8 80.4 (0.4) 0.0 0.0 25.1 OK 82.1 134.4 0.0 0.0 0.0 134.4 0.0 0.0 0.0 0.0 101 101.0 4.2 (0.7) 0.0 104.5 25.8 104.5 (0.5) 0.0 0.0 25.2 OK 107.1

90.0 0.0 0.0 0.0 90.0 0.0 0.0 0.0 0.0 55 55.0 2.6 (0.9) 0.0 56.7 25.8 56.7 (0.6) 0.0 (0.0) 25.2 OK 58.0

86.6 0.0 0.0 0.0 86.6 0.0 0.0 0.0 0.0 51 51.0 2.6 (1.3) 0.0 52.3 25.8 52.3 (1.0) 0.0 (0.1) 25.1 OK 53.3

80.1 1.8 7.8 7.8 72.3 0.0 0.8 0.8 0.0 33 33.0 1.4 (2.0) 0.0 32.4 25.8 32.4 (1.5) 0.0 (0.0) 25.1 OK 32.0

84.0 0.6 28.4 28.4 55.6 0.3 2.8 2.8 0.0 14 14.0 0.5 (2.6) 0.0 11.9 25.8 11.9 (1.9) 0.0 0.0 25.1 OK 10.3

83.5 15.4 40.1 40.1 43.4 1.2 3.9 3.9 0.0 9 9.0 0.2 (3.2) 0.0 6.0 25.8 6.0 (2.3) 0.0 0.0 25.2 OK 3.8

77.1 13.5 44.6 44.6 32.5 1.2 4.4 4.4 0.0 2 2.0 0.1 (3.4) 0.0 (1.3) 24.5 0.0 (2.5) 0.0 (2.4) 22.7 OK 0.0

70.8 21.2 40.0 40.0 30.8 1.8 3.9 3.9 0.0 0 0.0 0.1 (3.1) 0.0 (3.0) 21.5 0.0 (2.3) 0.0 (2.2) 20.5 OK 0.0

73.9 11.7 25.9 25.9 47.9 1.8 2.5 2.5 0.0 23 23.0 0.3 (2.2) 0.0 21.1 25.8 16.8 (1.6) 0.0 4.7 25.2 OK 10.7 1054.3 69.7 193.4 193.4 860.9 6.8 19.0 19.0 0.0 457 457.0 18.2 (22.0) 0.0 395.1 58 454 (16.2) 0.0 (0.2) 451 Total Inflows: 457 Total Inflows: 454 Total Excess Water: 451 Total Outflows: 0 Total Outflows: 0
Legend for Cell Shading
(25) = (Column 16 of previous month) + Column 12 + Column 13 + Column 14 - Column 23. If Column 25 < 0, then set Column 25 to 0. - Value not directly used (26) Monthly average historical irrigation demand for Town Field from 2019 to 2024 - Historical value used as reference (27) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of Town Field, 57 acres) x (irrigation efficiency of 0.8). If Column 27 < 0, then set Column 27 to 0. - Independent variable (manual input) (28) If Column 25 < Column 27, Column 25. Otherwise, Column 27. (29) = Column 25 - Column 28. If Column 29 < 0, then set Column 29 to 0. (30) Monthly average historical irrigation demand for City Field from 2018 to 2023. (31) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of City Field, 5.6 acres) x (irrigation efficiency of 0.8). If Column 31 < 0, then set Column 31 to 0. (32) If Column 29 < Column 31, Column 29. Otherwise, Column 31. (33) = (Column 16 from previous month) + Column 15 - (Pond 5 volume, 41.7 acre-feet). If Column 33 < 0, then set Column 33 to 0. (34) Manually entered to move water between Pond 5 and Pond 7 to approximately match historical Pond 5 volumes. Positive values indicate flow from Pond 5 to Pond 7. Negative values indicate flow from Pond 7 to Town Field/City Field. (35) = Column 33 + Column 34
(36) = (Column 1)/12 x (surface area of Pond 7, 5.3 acres) (37) = (Column 2)/12 x (surface area of Pond 7, 5.3 acres) (38) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 7, 5.3 acres). Percolation rate set to 0 inches per day. (39) = Column 35 + Column 36 + Column 37 + Column 38 - Column 41 (40) = Column 40 of previous month + Column 39 of current month. If this is greater than the Pond 7 volume of 25.8 acre-feet, Column 40 is set to 25.8. If this is < 0, Column 40 is set to 0. In August, Column 40 must be <= 0 in order for the balance to work. (41) Manually entered to move water between Pond 7 and Pond 6. Positive values indicate flow from Pond 7 to Pond 6. Negative values indicate flow from Pond 6 to Pond 7. (42) If Column 40 >= Pond 7 volume of 25.8 acre-feet, Column 42 = (Column 40 of previous month) + Column 39 + Column 41 - 25.8. If Column 40 < 25.8, Column 42 = Column 41. (43) = (Column 1)/12 x (surface area of Pond 6,3.9 acres) (44) = (Column 2)/12 x (surface area of Pond 6, 3.9 acres) (45) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 6, 3.9 acres). Percolation rate set to 0 inches per day. (46) = Column 42 + Column 43 + Column 44 + Column 45
(47) = Column 47 of previous month + Column 46 of current month. If this is greater than the Pond 6 storage volume of 25.2 acre-feet, Column 47 is set to 25.2. If Column 47 < 0, set to 0. In July, Column 47 must be <= 0 in order for the balance to work. (48) If (Column 46 of current month) + (Column 47 of previous month) > Pond 6 storage volume of 25.2 acre-feet, Column 48 = "Overflow". Otherwise, Column 48 = "OK". (49) Manually entered to move water between Pond 6 and New Storage/Disposal Site to ensure pond storage capacity is not exceeded.

13.4 0.0

0.1 0.2

1.1 0.4

0.1 3.1

1.9 1.9

0.7 1.7

2.1 Current Flows: 1-in-100 Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 1 (43)
Percolation Pond 6
Rainfall
988-50-24-10 8of16
City of Ione
Updated Water Balance
519
Section 13, Item J.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (17) (16) (18) (19) (20) (21) (23) (24) Climate Values, inches Inflows, ac-ft Treatment Ponds Storage Pond 5 Golf Course Irrigation Rainfall Ref. ET
Base
City I&I
Town
Field
Runoff
COWRF
Backwash
AWA
Backwash CDCR ARSA Rainfall Evap.

Total
Inflow to
Pond 5 Rainfall Evap.

To/From
Storage
Net
Storage
Historical
Storage
Historical
Demand
Theoretical
Demand
Theoretical
Pond Losses
Total
Theoretical
Demand
Provided
by City
Total
Provided
Oct. 1.2 3.24 48.5 1.9 0.0 4.9 0.71 27.3 0.5 (1.5) 55.0 0.4 (1.1) 4.9 37.1 37.1 37.4 21.9 0.5 22.4 0.0 22.4 Nov. 2.8 1.68 47.0 4.6 0.0 0.0 0.52 0.0 1.3 (0.8) 52.7 1.0 (0.6) (5.9) 31.2 31.8 16.4 0.0 0.0 0.0 0.0 0.0 Dec. 3.5 1.21 48.5 5.8 0.0 0.0 0.52 0.0 1.7 (0.6) 55.9 1.2 (0.4) (2.3) 28.9 28.5 0.0 0.0 0.0 0.0 0.0 0.0 Jan. 5.1 1.48 48.5 8.4 3.5 0.0 0.37 0.0 2.4 (0.7) 62.5 1.8 (0.5) 3.7 32.7 33.5 0.0 0.0 0.0 0.0 0.0 0.0 Feb. 3.1 1.95 43.8 5.2 0.0 0.0 0.46 0.0 1.5 (0.9) 50.0 1.1 (0.7) 1.4 34.1 34.7 0.0 0.0 0.0 0.0 0.0 0.0 Mar. 3.2 3.02 48.5 5.2 0.0 0.0 0.37 0.0 1.5 (1.4) 54.2 1.1 (1.1) 1.2 35.3 35.3 0.0 0.0 0.0 0.0 0.0 0.0 Apr. 1.8 4.57 47.0 2.9 0.0 5.3 0.58 35.3 0.8 (2.2) 54.4 0.6 (1.6) 3.6 38.9 38.2 8.8 29.3 0.7 30.0 0.0 30.0 May 0.6 5.97 48.5 1.0 0.0 9.1 0.55 70.1 0.3 (2.8) 56.6 0.2 (2.1) (0.4) 38.5 38.3 54.9 59.6 1.4 61.0 0.0 61.0 Jun. 0.2 7.19 47.0 0.3 0.0 12.0 0.25 92.4 0.1 (3.4) 56.2 0.1 (2.5) (7.7) 30.8 30.4 71.8 78.6 1.8 80.4 0.0 80.4 Jul. 0.1 7.64 48.5 0.1 0.0 13.1 0.58 100.9 0.0 (3.6) 58.7 0.0 (2.7) (3.8) 27.0 26.9 83.4 85.8 2.0 87.8 0.0 87.8 Aug. 0.1 6.98 47.0 0.2 0.0 11.8 0.49 91.1 0.1 (3.3) 56.2 0.0 (2.4) 0.5 27.5 27.7 78.1 77.5 1.8 79.3 0.0 79.3 Sep. 0.3 4.99 48.5 0.5 0.0 11.0 0.43 64.6 0.2 (2.4) 58.2 0.1 (1.7) 3.9 32.2 32.2 62.4 52.4 1.2 53.6 0.0 53.6 Total, AFY 22.0 49.9 571 36.1 3.5 67.2 5.83 481.7 10.5 (23.7) 670.7 7.7 (17.5) (0.8) 413.2 405.1 9.4 414.5 0 414.5 Base City Flow 0.510 mgd
Town Field Runoff Calculation Parameters LAA Information Pond Information Storage Soil Interception, inches 3 1 2 3 4 5 6 7
Percent Infiltration, saturated soil 0.4 Surface Area, acres 1.5 1.2 1.0 2.0 4.2 3.9 5.3 Percent Infiltration, unsaturated soil 0.6 Area, acres 57 5.6 130 3.1 Storage Volume, ac-ft 41.7 25.2 25.8 Min 2-month Rainfall for Saturation, inches 10 Crop Coefficient 0.32 0.32 0.88 -- Feb.-May. Perc. Rate, in/d 0.0 0.0 Max Precip Before Runoff Capture, inches 20 Irr. Efficiency 0.80 0.80 0.84 -- Jun.-Jan. Perc. Rate, in/d 0.0 0.0 (1) Average year rainfall from Ione NCDC station (#044283) Legend for Cell Shading (2) Reference evapotranspiration from Plymouth CIMIS station (Station 227) - Value not directly used (3) = (Base City Flow) x (number of days in month) x 3.07 - Historical value used as reference (4) = 3.07 x (I&I in million gallons]. I&I in million gallons = 0.539 x (rainfall in inches) - 0.012, using linear equation developed in this TM. - Independent variable (manual input) (5) = (Column 1 - Column 2 - interception of 3 inches - infiltration in inches)/(12 inches per foot) x (surface area of Town Field, 57 acres). If Column 1 > 8 inches, then set value of Column 1 to 8 inches.

Infiltration in inches = (percent infiltration) x (Column 1 - Column 2 - interception of 3 inches). If the sum of Column 1 in the current and previous month >= 10 inches, percent infiltration is 0.4. Otherwise, percent infiltration is 0.6. (6) = (Column 9) x (Percentage of monthly COWRF influent flow discarded as backwash as defined in COGC TM) (see Attachment D) (7) Average monthly AWA backwash flow from 2021 to 2024 (8) = 0. Assume no CDCR flow.
(9) = Column 21 / (1 - COWRF filter backwash percentage as defined in COGC TM) (see Attachment D) (10) = (Column 1)/12 x (surface area of Ponds 1-4, 5.7 acres) (11) = (Column 2)/12 x (surface area of Ponds 1-4, 5.7 acres) (12) = Column 3 + Column 4 + Column 5 + Column 6 + Column 7 + Column 10 + Column 11 (13) = (Column 1)/12 x (surface area of Pond 5, 4.2 acres) (14) = (Column 2)/12 x (surface area of Pond 5, 4.2 acres) (15) = Column 12 + Column 13 + Column 14 - (Column 23 + Column 28 + Column 32 + Column 34) (16) = Column 16 of previous month + Column 15 of current month. If this is greater than the Pond 5 volume of 41.7 acre-feet, Column 16 is set to 41.7.

In August, Column 16 is set to 22.9 and the value in Column 34 is adjusted so that the formula in Column 15 predicts this value. (17) Monthly average storage volume in Pond 5 from 2019 to 2024 (18) Historical irrigation demand for COGC, from COGC TM (see Attachment D) (19) = [Column 1 - (Column 2 x crop coefficient of 0.88)]/12 x (surface area of golf course, 130 acres) x (irrigation efficiency of 0.84). If Column 19 < 0, then set Column 19 to 0. (20) = (Column 1 - Column 2)/12 x (surface area of golf course pond, 3.1 acres). If Column 20 < 0, then set Column 20 to 0. (21) = Column 19 + Column 20
(22) = Column 21 - Column 23
(23) = 0. Assume no flow from the City.
(24) = Column 22 + Column 23
Town
Field
City
Field
Golf
Course

87.8 79.3

53.6 414.5
Golf
Course
Pond
Treatment Percolation

30.0 61.0

80.4 0.0

0.0 0.0

22.4 0.0

0.0 2030 Flows: Average Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 0.32 Month
(22)
Provided
by
Partners
988-50-24-10 9of16
City of Ione
Updated Water Balance
520
Section 13, Item J.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May
Jun.

Jul.

Aug.

Sep.

Total, AFY
Month
(25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (44) (45) (46) (47) (48) (49) Town Field Irrigation City Field Irrigation Percolation Pond 7 Avail for
Town
Historical
Demand
Theoretical
Demand
Provided
by City
Avail for
City
Historical
Demand
Theoretical
Demand
Provided
by City
System
Excess
Empty
Pond 5
Total
Flow to
Pond Rainfall Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Empty
Pond 7
Total
Flow to
Pond Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Check for
System
Overflow
Discharge/
Store
Elsewhere

86.5 4.3 4.0 4.0 82.5 0.3 0.4 0.4 0.0 45 45.0 0.5 (1.4) 0.0 (25.9) 0.0 70 70.0 (1.1) 0.0 (25.2) 0.0 OK 94.5

90.2 1.2 0.0 0.0 90.2 0.0 0.0 0.0 0.0 59 59.0 1.2 (0.7) 0.0 59.5 25.8 33.7 (0.5) 0.0 25.2 25.2 OK 8.9

87.9 0.0 0.0 0.0 87.9 0.0 0.0 0.0 0.0 59 59.0 1.6 (0.5) 0.0 60.0 25.8 60.0 (0.4) 0.0 (0.0) 25.1 OK 60.8

92.7 0.0 0.0 0.0 92.7 0.0 0.0 0.0 0.0 60 60.0 2.2 (0.7) 0.0 61.6 25.8 61.6 (0.5) 0.0 (0.0) 25.1 OK 62.8

83.1 0.0 0.0 0.0 83.1 0.0 0.0 0.0 0.0 49 49.0 1.4 (0.9) 0.0 49.5 25.8 49.5 (0.6) 0.0 0.0 25.1 OK 49.9

88.3 0.0 0.0 0.0 88.3 0.0 0.0 0.0 0.0 53 53.0 1.4 (1.3) 0.0 53.1 25.8 53.1 (1.0) 0.0 0.0 25.1 OK 53.1

88.8 1.8 5.4 5.4 83.4 0.0 0.5 0.5 0.0 44 44.0 0.8 (2.0) 0.0 42.8 25.8 42.8 (1.5) 0.0 0.0 25.2 OK 41.8

93.6 0.6 10.1 10.1 83.5 0.3 1.0 1.0 0.0 44 44.0 0.3 (2.6) 0.0 41.6 25.8 41.6 (1.9) 0.0 0.0 25.2 OK 39.9

92.3 15.4 13.2 13.2 79.1 1.2 1.3 1.3 0.0 47 47.0 0.1 (3.2) 0.0 43.9 25.8 43.9 (2.3) 0.0 (0.0) 25.2 OK 41.7

86.8 13.5 14.4 14.4 72.4 1.2 1.4 1.4 0.0 44 44.0 0.0 (3.4) 0.0 40.7 25.8 40.7 (2.5) 0.0 (0.0) 25.2 OK 38.2

80.8 21.2 13.0 13.0 67.8 1.8 1.3 1.3 0.0 39 39.0 0.1 (3.1) 0.0 36.0 25.8 36.0 (2.3) 0.0 (0.1) 25.1 OK 33.8

84.1 11.7 8.9 8.9 75.3 1.8 0.9 0.9 0.0 43 43.0 0.1 (2.2) 0.0 40.9 25.8 40.9 (1.6) 0.0 0.0 25.1 OK 39.4 1055.0 69.7 69.0 69.0 986.1 6.8 6.8 6.8 0.0 586 586.0 9.7 (22.0) 0.0 503.7 70 574 (16.2) 0.0 (0.1) 565 Total Inflows: 586 Total Inflows: 574 Total Excess Water: 565 Total Outflows: 0 Total Outflows: 0
Legend for Cell Shading
(25) = (Column 16 of previous month) + Column 12 + Column 13 + Column 14 - Column 23. If Column 25 < 0, then set Column 25 to 0. - Value not directly used (26) Monthly average historical irrigation demand for Town Field from 2019 to 2024 - Historical value used as reference (27) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of Town Field, 57 acres) x (irrigation efficiency of 0.8). If Column 27 < 0, then set Column 27 to 0. - Independent variable (manual input) (28) If Column 25 < Column 27, Column 25. Otherwise, Column 27. (29) = Column 25 - Column 28. If Column 29 < 0, then set Column 29 to 0. (30) Monthly average historical irrigation demand for City Field from 2018 to 2023. (31) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of City Field, 5.6 acres) x (irrigation efficiency of 0.8). If Column 31 < 0, then set Column 31 to 0. (32) If Column 29 < Column 31, Column 29. Otherwise, Column 31. (33) = (Column 16 from previous month) + Column 15 - (Pond 5 volume, 41.7 acre-feet). If Column 33 < 0, then set Column 33 to 0. (34) Manually entered to move water between Pond 5 and Pond 7 to approximately match historical Pond 5 volumes. Positive values indicate flow from Pond 5 to Pond 7. Negative values indicate flow from Pond 7 to Town Field/City Field. (35) = Column 33 + Column 34
(36) = (Column 1)/12 x (surface area of Pond 7, 5.3 acres) (37) = (Column 2)/12 x (surface area of Pond 7, 5.3 acres) (38) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 7, 5.3 acres). Percolation rate set to 0 inches per day. (39) = Column 35 + Column 36 + Column 37 + Column 38 - Column 41 (40) = Column 40 of previous month + Column 39 of current month. If this is greater than the Pond 7 volume of 25.8 acre-feet, Column 40 is set to 25.8. If this is < 0, Column 40 is set to 0. In August, Column 40 must be <= 0 in order for the balance to work. (41) Manually entered to move water between Pond 7 and Pond 6. Positive values indicate flow from Pond 7 to Pond 6. Negative values indicate flow from Pond 6 to Pond 7. (42) If Column 40 >= Pond 7 volume of 25.8 acre-feet, Column 42 = (Column 40 of previous month) + Column 39 + Column 41 - 25.8. If Column 40 < 25.8, Column 42 = Column 41. (43) = (Column 1)/12 x (surface area of Pond 6,3.9 acres) (44) = (Column 2)/12 x (surface area of Pond 6, 3.9 acres) (45) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 6, 3.9 acres). Percolation rate set to 0 inches per day. (46) = Column 42 + Column 43 + Column 44 + Column 45
(47) = Column 47 of previous month + Column 46 of current month. If this is greater than the Pond 6 storage volume of 25.2 acre-feet, Column 47 is set to 25.2. If Column 47 < 0, set to 0. In July, Column 47 must be <= 0 in order for the balance to work. (48) If (Column 46 of current month) + (Column 47 of previous month) > Pond 6 storage volume of 25.2 acre-feet, Column 48 = "Overflow". Otherwise, Column 48 = "OK". (49) Manually entered to move water between Pond 6 and New Storage/Disposal Site to ensure pond storage capacity is not exceeded.

0.0 0.0

0.1 7.2

0.6 0.2

0.1 1.7

1.0 1.0

0.4 0.9

1.1 (43)
Percolation Pond 6
Rainfall
2030 Flows: Average Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 0.32 988-50-24-10 10of16
City of Ione
Updated Water Balance
521
Section 13, Item J.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (17) (16) (18) (19) (20) (21) (23) (24) Climate Values, inches Inflows, ac-ft Treatment Ponds Storage Pond 5 Golf Course Irrigation Rainfall Ref. ET
Base
City I&I
Town
Field
Runoff
COWRF
Backwash
AWA
Backwash CDCR ARSA Rainfall Evap.

Total
Inflow to
Pond 5 Rainfall Evap.

To/From
Storage
Net
Storage
Historical
Storage
Historical
Demand
Theoretical
Demand
Theoretical
Pond Losses
Total
Theoretical
Demand
Provided
by City
Total
Provided
Oct. 1.2 3.24 48.5 1.9 0.0 4.9 0.71 27.3 0.5 (1.5) 55.0 0.4 (1.1) 5.7 37.9 37.1 37.4 21.9 0.5 22.4 0.0 22.4 Nov. 2.8 1.68 47.0 4.6 0.0 0.0 0.52 0.0 1.3 (0.8) 52.7 1.0 (0.6) (5.9) 31.9 31.8 16.4 0.0 0.0 0.0 0.0 0.0 Dec. 3.5 1.21 48.5 5.8 0.0 0.0 0.52 0.0 1.7 (0.6) 55.9 1.2 (0.4) (3.3) 28.6 28.5 0.0 0.0 0.0 0.0 0.0 0.0 Jan. 5.1 1.48 48.5 8.4 3.5 0.0 0.37 0.0 2.4 (0.7) 62.5 1.8 (0.5) 4.7 33.4 33.5 0.0 0.0 0.0 0.0 0.0 0.0 Feb. 3.1 1.95 43.8 5.2 0.0 0.0 0.46 0.0 1.5 (0.9) 50.0 1.1 (0.7) 1.4 34.8 34.7 0.0 0.0 0.0 0.0 0.0 0.0 Mar. 3.2 3.02 48.5 5.2 0.0 0.0 0.37 0.0 1.5 (1.4) 54.2 1.1 (1.1) 0.2 35.0 35.3 0.0 0.0 0.0 0.0 0.0 0.0 Apr. 1.8 4.57 47.0 2.9 0.0 5.3 0.58 35.3 0.8 (2.2) 54.4 0.6 (1.6) 3.1 38.1 38.2 8.8 29.3 0.7 30.0 0.0 30.0 May 0.6 5.97 48.5 1.0 0.0 9.1 0.55 70.1 0.3 (2.8) 56.6 0.2 (2.1) (0.1) 38.0 38.3 54.9 59.6 1.4 61.0 0.0 61.0 Jun. 0.2 7.19 47.0 0.3 0.0 12.0 0.25 92.4 0.1 (3.4) 56.2 0.1 (2.5) (7.6) 30.4 30.4 71.8 78.6 1.8 80.4 0.0 80.4 Jul. 0.1 7.64 48.5 0.1 0.0 13.1 0.58 100.9 0.0 (3.6) 58.7 0.0 (2.7) (3.3) 27.1 26.9 83.4 85.8 2.0 87.8 0.0 87.8 Aug. 0.1 6.98 47.0 0.2 0.0 11.8 0.49 91.1 0.1 (3.3) 56.2 0.0 (2.4) 0.2 27.3 27.7 78.1 77.5 1.8 79.3 0.0 79.3 Sep. 0.3 4.99 48.5 0.5 0.0 11.0 0.43 64.6 0.2 (2.4) 58.2 0.1 (1.7) 4.2 32.2 32.2 62.4 52.4 1.2 53.6 0.0 53.6 Total, AFY 22.0 49.9 571 36.1 3.5 67.2 5.83 481.7 10.5 (23.7) 670.7 7.7 (17.5) (0.7) 413.2 405.1 9.4 414.5 0 414.5 Base City Flow 0.510 mgd
Town Field Runoff Calculation Parameters LAA Information Pond Information Storage Soil Interception, inches 3 1 2 3 4 5 6 7
Percent Infiltration, saturated soil 0.4 Surface Area, acres 1.5 1.2 1.0 2.0 4.2 3.9 5.3 Percent Infiltration, unsaturated soil 0.6 Area, acres 57 5.6 130 3.1 Storage Volume, ac-ft 41.7 25.2 25.8 Min 2-month Rainfall for Saturation, inches 10 Crop Coefficient 1.00 1.00 0.88 -- Feb.-May. Perc. Rate, in/d 0.0 0.0 Max Precip Before Runoff Capture, inches 20 Irr. Efficiency 0.80 0.80 0.84 -- Jun.-Jan. Perc. Rate, in/d 0.0 0.0 (1) Average year rainfall from Ione NCDC station (#044283) Legend for Cell Shading (2) Reference evapotranspiration from Plymouth CIMIS station (Station 227) - Value not directly used (3) = (Base City Flow) x (number of days in month) x 3.07 - Historical value used as reference (4) = 3.07 x (I&I in million gallons]. I&I in million gallons = 0.539 x (rainfall in inches) - 0.012, using linear equation developed in this TM. - Independent variable (manual input) (5) = (Column 1 - Column 2 - interception of 3 inches - infiltration in inches)/(12 inches per foot) x (surface area of Town Field, 57 acres). If Column 1 > 8 inches, then set value of Column 1 to 8 inches.

Infiltration in inches = (percent infiltration) x (Column 1 - Column 2 - interception of 3 inches). If the sum of Column 1 in the current and previous month >= 10 inches, percent infiltration is 0.4. Otherwise, percent infiltration is 0.6. (6) = (Column 9) x (Percentage of monthly COWRF influent flow discarded as backwash as defined in COGC TM) (see Attachment D) (7) Average monthly AWA backwash flow from 2021 to 2024 (8) = 0. Assume no CDCR flow.
(9) = Column 21 / (1 - COWRF filter backwash percentage as defined in COGC TM) (see Attachment D) (10) = (Column 1)/12 x (surface area of Ponds 1-4, 5.7 acres) (11) = (Column 2)/12 x (surface area of Ponds 1-4, 5.7 acres) (12) = Column 3 + Column 4 + Column 5 + Column 6 + Column 7 + Column 10 + Column 11 (13) = (Column 1)/12 x (surface area of Pond 5, 4.2 acres) (14) = (Column 2)/12 x (surface area of Pond 5, 4.2 acres) (15) = Column 12 + Column 13 + Column 14 - (Column 23 + Column 28 + Column 32 + Column 34) (16) = Column 16 of previous month + Column 15 of current month. If this is greater than the Pond 5 volume of 41.7 acre-feet, Column 16 is set to 41.7.

In September, Column 16 is set to 0 and the value in Column 34 is adjusted so that the formula in Column 15 predicts this value. (17) Monthly average storage volume in Pond 5 from 2019 to 2024 (18) Historical irrigation demand for COGC, from COGC TM (see Attachment D) (19) = [Column 1 - (Column 2 x crop coefficient of 0.88)]/12 x (surface area of golf course, 130 acres) x (irrigation efficiency of 0.84). If Column 19 < 0, then set Column 19 to 0. (20) = (Column 1 - Column 2)/12 x (surface area of golf course pond, 3.1 acres). If Column 20 < 0, then set Column 20 to 0. (21) = Column 19 + Column 20
(22) = Column 21 - Column 23
(23) = 0. Assume no flow from the City.
(24) = Column 22 + Column 23
Town
Field
City
Field
Golf
Course

87.8 79.3

53.6 414.5
Golf
Course
Pond
Treatment Percolation

30.0 61.0

80.4 0.0

0.0 0.0

22.4 0.0

0.0 2030 Flows: Average Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 1 Month
(22)
Provided
by
Partners
988-50-24-10 11of16
City of Ione
Updated Water Balance
522
Section 13, Item J.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May
Jun.

Jul.

Aug.

Sep.

Total, AFY
Month
(25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (44) (45) (46) (47) (48) (49) Town Field Irrigation City Field Irrigation Percolation Pond 7 Avail for
Town
Historical
Demand
Theoretical
Demand
Provided
by City
Avail for
City
Historical
Demand
Theoretical
Demand
Provided
by City
System
Excess
Empty
Pond 5
Total
Flow to
Pond Rainfall Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Empty
Pond 7
Total
Flow to
Pond Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Check for
System
Overflow
Discharge/St
ore
Elsewhere

86.5 4.3 12.4 12.4 74.1 0.3 1.2 1.2 0.0 35 35.0 0.5 (1.4) 0.0 (25.9) 0.0 60 60.0 (1.1) 0.0 (24.9) 0.0 OK 84.2

90.9 1.2 0.0 0.0 90.9 0.0 0.0 0.0 0.0 59 59.0 1.2 (0.7) 0.0 59.5 25.8 33.7 (0.5) 0.0 24.8 24.8 OK 9.3

88.6 0.0 0.0 0.0 88.6 0.0 0.0 0.0 0.0 60 60.0 1.6 (0.5) 0.0 61.0 25.8 61.0 (0.4) 0.0 (0.0) 24.7 OK 61.8

92.4 0.0 0.0 0.0 92.4 0.0 0.0 0.0 0.0 59 59.0 2.2 (0.7) 0.0 60.6 25.8 60.6 (0.5) 0.0 (0.0) 24.7 OK 61.8

83.8 0.0 0.0 0.0 83.8 0.0 0.0 0.0 0.0 49 49.0 1.4 (0.9) 0.0 49.5 25.8 49.5 (0.6) 0.0 0.0 24.7 OK 49.9

89.0 0.0 0.0 0.0 89.0 0.0 0.0 0.0 0.0 54 54.0 1.4 (1.3) 0.0 54.1 25.8 54.1 (1.0) 0.0 0.0 24.7 OK 54.1

88.5 1.8 16.7 16.7 71.7 0.0 1.6 1.6 0.0 32 32.0 0.8 (2.0) 0.0 30.8 25.8 30.8 (1.5) 0.0 0.0 24.8 OK 29.8

92.8 0.6 31.7 31.7 61.1 0.3 3.1 3.1 0.0 20 20.0 0.3 (2.6) 0.0 17.6 25.8 17.6 (1.9) 0.0 0.0 24.8 OK 15.9

91.8 15.4 41.3 41.3 50.5 1.2 4.1 4.1 0.0 16 16.0 0.1 (3.2) 0.0 12.9 25.8 12.9 (2.3) 0.0 (0.0) 24.8 OK 10.7

86.5 13.5 44.9 44.9 41.5 1.2 4.4 4.4 0.0 10 10.0 0.0 (3.4) 0.0 6.7 25.8 6.7 (2.5) 0.0 (0.0) 24.8 OK 4.2

81.0 21.2 40.7 40.7 40.3 1.8 4.0 4.0 0.0 9 9.0 0.1 (3.1) 0.0 6.0 25.8 6.0 (2.3) 0.0 0.0 24.8 OK 3.7

83.9 11.7 27.7 27.7 56.2 1.8 2.7 2.7 0.0 22 22.0 0.1 (2.2) 0.0 19.9 25.8 19.9 (1.6) 0.0 0.0 24.8 OK 18.4 1055.8 69.7 215.5 215.5 840.3 6.8 21.2 21.2 0.0 425 425.0 9.7 (22.0) 0.0 352.7 60 413 (16.2) 0.0 (0.1) 404 Total Inflows: 425 Total Inflows: 413 Total Excess Water: 404 Total Outflows: 0 Total Outflows: 0
Legend for Cell Shading
(25) = (Column 16 of previous month) + Column 12 + Column 13 + Column 14 - Column 23. If Column 25 < 0, then set Column 25 to 0. - Value not directly used (26) Monthly average historical irrigation demand for Town Field from 2019 to 2024 - Historical value used as reference (27) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of Town Field, 57 acres) x (irrigation efficiency of 0.8). If Column 27 < 0, then set Column 27 to 0. - Independent variable (manual input) (28) If Column 25 < Column 27, Column 25. Otherwise, Column 27. (29) = Column 25 - Column 28. If Column 29 < 0, then set Column 29 to 0. (30) Monthly average historical irrigation demand for City Field from 2018 to 2023. (31) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of City Field, 5.6 acres) x (irrigation efficiency of 0.8). If Column 31 < 0, then set Column 31 to 0. (32) If Column 29 < Column 31, Column 29. Otherwise, Column 31. (33) = (Column 16 from previous month) + Column 15 - (Pond 5 volume, 41.7 acre-feet). If Column 33 < 0, then set Column 33 to 0. (34) Manually entered to move water between Pond 5 and Pond 7 to approximately match historical Pond 5 volumes. Positive values indicate flow from Pond 5 to Pond 7. Negative values indicate flow from Pond 7 to Town Field/City Field. (35) = Column 33 + Column 34
(36) = (Column 1)/12 x (surface area of Pond 7, 5.3 acres) (37) = (Column 2)/12 x (surface area of Pond 7, 5.3 acres) (38) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 7, 5.3 acres). Percolation rate set to 0 inches per day. (39) = Column 35 + Column 36 + Column 37 + Column 38 - Column 41 (40) = Column 40 of previous month + Column 39 of current month. If this is greater than the Pond 7 volume of 25.8 acre-feet, Column 40 is set to 25.8. If this is < 0, Column 40 is set to 0. In August, Column 40 must be <= 0 in order for the balance to work. (41) Manually entered to move water between Pond 7 and Pond 6. Positive values indicate flow from Pond 7 to Pond 6. Negative values indicate flow from Pond 6 to Pond 7. (42) If Column 40 >= Pond 7 volume of 25.8 acre-feet, Column 42 = (Column 40 of previous month) + Column 39 + Column 41 - 25.8. If Column 40 < 25.8, Column 42 = Column 41. (43) = (Column 1)/12 x (surface area of Pond 6,3.9 acres) (44) = (Column 2)/12 x (surface area of Pond 6, 3.9 acres) (45) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 6, 3.9 acres). Percolation rate set to 0 inches per day. (46) = Column 42 + Column 43 + Column 44 + Column 45
(47) = Column 47 of previous month + Column 46 of current month. If this is greater than the Pond 6 storage volume of 25.2 acre-feet, Column 47 is set to 25.2. If Column 47 < 0, set to 0. In July, Column 47 must be <= 0 in order for the balance to work. (48) If (Column 46 of current month) + (Column 47 of previous month) > Pond 6 storage volume of 25.2 acre-feet, Column 48 = "Overflow". Otherwise, Column 48 = "OK". (49) Manually entered to move water between Pond 6 and New Storage/Disposal Site to ensure pond storage capacity is not exceeded.

0.0 0.0

0.1 7.2

0.6 0.2

0.1 1.7

1.0 1.0

0.4 0.9

1.1 (43)
Percolation Pond 6
Rainfall
2030 Flows: Average Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 1 988-50-24-10 12of16
City of Ione
Updated Water Balance
523
Section 13, Item J.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (17) (16) (18) (19) (20) (21) (23) (24) Climate Values, inches Inflows, ac-ft Treatment Ponds Storage Pond 5 Golf Course Irrigation Rainfall Ref. ET
Base
City I&I
Town
Field
Runoff
COWRF
Backwash
AWA
Backwash CDCR ARSA Rainfall Evap.

Total
Inflow to
Pond 5 Rainfall Evap.

To/From
Storage
Net
Storage
Historical
Storage
Historical
Demand
Theoretical
Demand
Theoretical
Pond Losses
Total
Theoretical
Demand
Provided
by City
Total
Provided
Oct. 2.2 3.24 48.5 3.5 0.0 2.0 0.71 11.3 1.0 (1.5) 54.2 0.8 (1.1) 4.5 36.7 37.1 37.4 9.0 0.3 9.3 0.0 9.3 Nov. 5.2 1.68 47.0 8.6 3.3 0.0 0.52 0.0 2.5 (0.8) 61.1 1.8 (0.6) (5.6) 31.1 31.8 16.4 0.0 0.0 0.0 0.0 0.0 Dec. 6.6 1.21 48.5 10.8 20.7 0.0 0.52 0.0 3.1 (0.6) 83.1 2.3 (0.4) (3.0) 28.0 28.5 0.0 0.0 0.0 0.0 0.0 0.0 Jan. 9.5 1.48 48.5 15.7 43.7 0.0 0.37 0.0 4.5 (0.7) 112.1 3.3 (0.5) 4.9 32.9 33.5 0.0 0.0 0.0 0.0 0.0 0.0 Feb. 5.9 1.95 43.8 9.7 8.0 0.0 0.46 0.0 2.8 (0.9) 63.8 2.1 (0.7) 1.2 34.1 34.7 0.0 0.0 0.0 0.0 0.0 0.0 Mar. 6.0 3.02 48.5 9.8 0.0 0.0 0.37 0.0 2.8 (1.4) 60.1 2.1 (1.1) 1.1 35.2 35.3 0.0 0.0 0.0 0.0 0.0 0.0 Apr. 3.3 4.57 47.0 5.4 0.0 1.8 0.58 11.9 1.5 (2.2) 54.2 1.1 (1.6) 3.0 38.2 38.2 8.8 9.8 0.3 10.1 0.0 10.1 May 1.2 5.97 48.5 1.9 0.0 8.0 0.55 61.7 0.6 (2.8) 56.7 0.4 (2.1) 0.0 38.2 38.3 54.9 52.5 1.2 53.7 0.0 53.7 Jun. 0.4 7.19 47.0 0.7 0.0 11.6 0.25 89.4 0.2 (3.4) 56.3 0.2 (2.5) (8.1) 30.0 30.4 71.8 76.1 1.7 77.8 0.0 77.8 Jul. 0.1 7.64 48.5 0.2 0.0 13.0 0.58 99.9 0.1 (3.6) 58.7 0.0 (2.7) (3.6) 26.4 26.9 83.4 85.0 1.9 86.9 0.0 86.9 Aug. 0.2 6.98 47.0 0.4 0.0 11.6 0.49 89.4 0.1 (3.3) 56.3 0.1 (2.4) 0.9 27.3 27.7 78.1 76.1 1.7 77.8 0.0 77.8 Sep. 0.6 4.99 48.5 1.0 0.0 10.2 0.43 59.9 0.3 (2.4) 58.1 0.2 (1.7) 5.4 32.2 32.2 62.4 48.6 1.1 49.7 0.0 49.7 Total, AFY 41.1 49.9 571 67.7 75.7 58.2 5.83 423.5 19.5 (23.7) 774.6 14.4 (17.5) 0.5 413.2 357.1 8.2 365.3 0 365.3 Base City Flow 0.510 mgd
Town Field Runoff Calculation Parameters LAA Information Pond Information Storage Soil Interception, inches 3 1 2 3 4 5 6 7
Percent Infiltration, saturated soil 0.4 Surface Area, acres 1.5 1.2 1.0 2.0 4.2 3.9 5.3 Percent Infiltration, unsaturated soil 0.6 Area, acres 57 5.6 130 3.1 Storage Volume, ac-ft 41.7 25.2 25.8 Min 2-month Rainfall for Saturation, inches 10 Crop Coefficient 0.32 0.32 0.88 -- Feb.-May. Perc. Rate, in/d 0.0 0.0 Max Precip Before Runoff Capture, inches 20 Irr. Efficiency 0.80 0.80 0.84 -- Jun.-Jan. Perc. Rate, in/d 0.0 0.0 (1) 1-in-100 year rainfall from Ione NCDC station (#044283) Legend for Cell Shading (2) Reference evapotranspiration from Plymouth CIMIS station (Station 227) - Value not directly used (3) = (Base City Flow) x (number of days in month) x 3.07 - Historical value used as reference (4) = 3.07 x (I&I in million gallons]. I&I in million gallons = 0.539 x (rainfall in inches) - 0.012, using linear equation developed in this TM. - Independent variable (manual input) (5) = (Column 1 - Column 2 - interception of 3 inches - infiltration in inches)/(12 inches per foot) x (surface area of Town Field, 57 acres). If Column 1 > 8 inches, then set value of Column 1 to 8 inches.

Infiltration in inches = (percent infiltration) x (Column 1 - Column 2 - interception of 3 inches). If the sum of Column 1 in the current and previous month >= 10 inches, percent infiltration is 0.4. Otherwise, percent infiltration is 0.6. (6) = (Column 9) x (Percentage of monthly COWRF influent flow discarded as backwash as defined in COGC TM) (see Attachment D) (7) Average monthly AWA backwash flow from 2021 to 2024 (8) = 0. Assume no CDCR flow.
(9) = Column 21 / (1 - COWRF filter backwash percentage as defined in COGC TM) (see Attachment D) (10) = (Column 1)/12 x (surface area of Ponds 1-4, 5.7 acres) (11) = (Column 2)/12 x (surface area of Ponds 1-4, 5.7 acres) (12) = Column 3 + Column 4 + Column 5 + Column 6 + Column 7 + Column 10 + Column 11 (13) = (Column 1)/12 x (surface area of Pond 5, 4.2 acres) (14) = (Column 2)/12 x (surface area of Pond 5, 4.2 acres) (15) = Column 12 + Column 13 + Column 14 - (Column 23 + Column 28 + Column 32 + Column 34) (16) = Column 16 of previous month + Column 15 of current month. If this is greater than the Pond 5 volume of 41.7 acre-feet, Column 16 is set to 41.7.

In August, Column 16 is set to 21.2 and the value in Column 34 is adjusted so that the formula in Column 15 predicts this value. (17) Monthly average storage volume in Pond 5 from 2019 to 2024 (18) Historical irrigation demand for COGC, from COGC TM (see Attachment D) (19) = [Column 1 - (Column 2 x crop coefficient of 0.88)]/12 x (surface area of golf course, 130 acres) x (irrigation efficiency of 0.84). If Column 19 < 0, then set Column 19 to 0. (20) = (Column 1 - Column 2)/12 x (surface area of golf course pond, 3.1 acres). If Column 20 < 0, then set Column 20 to 0. (21) = Column 19 + Column 20
(22) = Column 21 - Column 23
(23) = 0. Assume no flow from the City.
(24) = Column 22 + Column 23
Town
Field
City
Field
Golf
Course

86.9 77.8

49.7 365.3
Golf
Course
Pond
Treatment Percolation

10.1 53.7

77.8 0.0

0.0 0.0

9.3 0.0

0.0 2030 Flows: 1-in-100 Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 0.32 Month
(22)
Provided
by
Partners
988-50-24-10 13of16
City of Ione
Updated Water Balance
524
Section 13, Item J.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May
Jun.

Jul.

Aug.

Sep.

Total, AFY
Month
(25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (44) (45) (46) (47) (48) (49) Town Field Irrigation City Field Irrigation Percolation Pond 7 Avail for
Town
Historical
Demand
Theoretical
Demand
Provided
by City
Avail for
City
Historical
Demand
Theoretical
Demand
Provided
by City
System
Excess
Empty
Pond 5
Total
Flow to
Pond Rainfall Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Empty
Pond 7
Total
Flow to
Pond Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Check for
System
Overflow
Discharge/
Store
Elsewhere

86.0 4.3 2.1 2.1 83.9 0.3 0.2 0.2 0.0 47 47.0 0.9 (1.4) 0.0 (26.5) 0.0 73 73.0 (1.1) 0.0 (25.3) 0.0 OK 97.9

99.1 1.2 0.0 0.0 99.1 0.0 0.0 0.0 0.0 68 68.0 2.3 (0.7) 0.0 69.6 25.8 43.8 (0.5) 0.0 25.1 25.1 OK 19.8 116.0 0.0 0.0 0.0 116.0 0.0 0.0 0.0 0.0 88 88.0 2.9 (0.5) 0.0 90.4 25.8 90.4 (0.4) 0.0 0.0 25.1 OK 92.1 142.9 0.0 0.0 0.0 142.9 0.0 0.0 0.0 0.0 110 110.0 4.2 (0.7) 0.0 113.5 25.8 113.5 (0.5) 0.0 0.0 25.2 OK 116.1

98.1 0.0 0.0 0.0 98.1 0.0 0.0 0.0 0.0 64 64.0 2.6 (0.9) 0.0 65.7 25.8 65.7 (0.6) 0.0 (0.0) 25.2 OK 67.0

95.2 0.0 0.0 0.0 95.2 0.0 0.0 0.0 0.0 60 60.0 2.6 (1.3) 0.0 61.3 25.8 61.3 (1.0) 0.0 (0.1) 25.1 OK 62.3

88.9 1.8 2.5 2.5 86.4 0.0 0.2 0.2 0.0 48 48.0 1.4 (2.0) 0.0 47.4 25.8 47.4 (1.5) 0.0 (0.0) 25.1 OK 47.0

93.2 0.6 9.1 9.1 84.0 0.3 0.9 0.9 0.0 45 45.0 0.5 (2.6) 0.0 42.9 25.8 42.9 (1.9) 0.0 0.0 25.1 OK 41.3

92.1 15.4 12.8 12.8 79.3 1.2 1.3 1.3 0.0 48 48.0 0.2 (3.2) 0.0 45.0 25.8 45.0 (2.3) 0.0 (0.1) 25.1 OK 42.9

86.1 13.5 14.3 14.3 71.8 1.2 1.4 1.4 0.0 44 44.0 0.1 (3.4) 0.0 40.7 25.8 40.7 (2.5) 0.0 0.0 25.1 OK 38.2

80.4 21.2 12.8 12.8 67.6 1.8 1.3 1.3 0.0 39 39.0 0.1 (3.1) 0.0 36.0 25.8 36.0 (2.3) 0.0 0.0 25.1 OK 33.8

83.8 11.7 8.3 8.3 75.5 1.8 0.8 0.8 0.0 42 42.0 0.3 (2.2) 0.0 40.1 25.8 40.1 (1.6) 0.0 0.0 25.2 OK 38.6 1161.8 69.7 61.9 61.9 1099.9 6.8 6.1 6.1 0.0 703 703.0 18.2 (22.0) 0.0 626.1 73 700 (16.2) 0.0 (0.1) 697 Total Inflows: 703 Total Inflows: 700 Total Excess Water: 697 Total Outflows: 0 Total Outflows: 0
Legend for Cell Shading
(25) = (Column 16 of previous month) + Column 12 + Column 13 + Column 14 - Column 23. If Column 25 < 0, then set Column 25 to 0. - Value not directly used (26) Monthly average historical irrigation demand for Town Field from 2019 to 2024 - Historical value used as reference (27) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of Town Field, 57 acres) x (irrigation efficiency of 0.8). If Column 27 < 0, then set Column 27 to 0. - Independent variable (manual input) (28) If Column 25 < Column 27, Column 25. Otherwise, Column 27. (29) = Column 25 - Column 28. If Column 29 < 0, then set Column 29 to 0. (30) Monthly average historical irrigation demand for City Field from 2018 to 2023. (31) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of City Field, 5.6 acres) x (irrigation efficiency of 0.8). If Column 31 < 0, then set Column 31 to 0. (32) If Column 29 < Column 31, Column 29. Otherwise, Column 31. (33) = (Column 16 from previous month) + Column 15 - (Pond 5 volume, 41.7 acre-feet). If Column 33 < 0, then set Column 33 to 0. (34) Manually entered to move water between Pond 5 and Pond 7 to approximately match historical Pond 5 volumes. Positive values indicate flow from Pond 5 to Pond 7. Negative values indicate flow from Pond 7 to Town Field/City Field. (35) = Column 33 + Column 34
(36) = (Column 1)/12 x (surface area of Pond 7, 5.3 acres) (37) = (Column 2)/12 x (surface area of Pond 7, 5.3 acres) (38) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 7, 5.3 acres). Percolation rate set to 0 inches per day. (39) = Column 35 + Column 36 + Column 37 + Column 38 - Column 41 (40) = Column 40 of previous month + Column 39 of current month. If this is greater than the Pond 7 volume of 25.8 acre-feet, Column 40 is set to 25.8. If this is < 0, Column 40 is set to 0. In August, Column 40 must be <= 0 in order for the balance to work. (41) Manually entered to move water between Pond 7 and Pond 6. Positive values indicate flow from Pond 7 to Pond 6. Negative values indicate flow from Pond 6 to Pond 7. (42) If Column 40 >= Pond 7 volume of 25.8 acre-feet, Column 42 = (Column 40 of previous month) + Column 39 + Column 41 - 25.8. If Column 40 < 25.8, Column 42 = Column 41. (43) = (Column 1)/12 x (surface area of Pond 6,3.9 acres) (44) = (Column 2)/12 x (surface area of Pond 6, 3.9 acres) (45) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 6, 3.9 acres). Percolation rate set to 0 inches per day. (46) = Column 42 + Column 43 + Column 44 + Column 45
(47) = Column 47 of previous month + Column 46 of current month. If this is greater than the Pond 6 storage volume of 25.2 acre-feet, Column 47 is set to 25.2. If Column 47 < 0, set to 0. In July, Column 47 must be <= 0 in order for the balance to work. (48) If (Column 46 of current month) + (Column 47 of previous month) > Pond 6 storage volume of 25.2 acre-feet, Column 48 = "Overflow". Otherwise, Column 48 = "OK". (49) Manually entered to move water between Pond 6 and New Storage/Disposal Site to ensure pond storage capacity is not exceeded.

0.0 0.1

0.2 13.4

1.1 0.4

0.1 3.1

1.9 1.9

0.7 1.7

2.1 (43)
Percolation Pond 6
Rainfall
2030 Flows: 1-in-100 Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 0.32 988-50-24-10 14of16
City of Ione
Updated Water Balance
525
Section 13, Item J.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (17) (16) (18) (19) (20) (21) (23) (24) Climate Values, inches Inflows, ac-ft Treatment Ponds Storage Pond 5 Golf Course Irrigation Rainfall Ref. ET
Base
City I&I
Town
Field
Runoff
COWRF
Backwash
AWA
Backwash CDCR ARSA Rainfall Evap.

Total
Inflow to
Pond 5 Rainfall Evap.

To/From
Storage
Net
Storage
Historical
Storage
Historical
Demand
Theoretical
Demand
Theoretical
Pond Losses
Total
Theoretical
Demand
Provided
by City
Total
Provided
Oct. 2.2 3.24 48.5 3.5 0.0 2.0 0.71 11.3 1.0 (1.5) 54.2 0.8 (1.1) 5.7 37.9 37.1 37.4 9.0 0.3 9.3 0.0 9.3 Nov. 5.2 1.68 47.0 8.6 3.3 0.0 0.52 0.0 2.5 (0.8) 61.1 1.8 (0.6) (6.6) 31.3 31.8 16.4 0.0 0.0 0.0 0.0 0.0 Dec. 6.6 1.21 48.5 10.8 20.7 0.0 0.52 0.0 3.1 (0.6) 83.1 2.3 (0.4) (3.0) 28.2 28.5 0.0 0.0 0.0 0.0 0.0 0.0 Jan. 9.5 1.48 48.5 15.7 43.7 0.0 0.37 0.0 4.5 (0.7) 112.1 3.3 (0.5) 4.9 33.1 33.5 0.0 0.0 0.0 0.0 0.0 0.0 Feb. 5.9 1.95 43.8 9.7 8.0 0.0 0.46 0.0 2.8 (0.9) 63.8 2.1 (0.7) 1.2 34.3 34.7 0.0 0.0 0.0 0.0 0.0 0.0 Mar. 6.0 3.02 48.5 9.8 0.0 0.0 0.37 0.0 2.8 (1.4) 60.1 2.1 (1.1) 1.1 35.4 35.3 0.0 0.0 0.0 0.0 0.0 0.0 Apr. 3.3 4.57 47.0 5.4 0.0 1.8 0.58 11.9 1.5 (2.2) 54.2 1.1 (1.6) 3.2 38.5 38.2 8.8 9.8 0.3 10.1 0.0 10.1 May 1.2 5.97 48.5 1.9 0.0 8.0 0.55 61.7 0.6 (2.8) 56.7 0.4 (2.1) (0.2) 38.3 38.3 54.9 52.5 1.2 53.7 0.0 53.7 Jun. 0.4 7.19 47.0 0.7 0.0 11.6 0.25 89.4 0.2 (3.4) 56.3 0.2 (2.5) (8.1) 30.2 30.4 71.8 76.1 1.7 77.8 0.0 77.8 Jul. 0.1 7.64 48.5 0.2 0.0 13.0 0.58 99.9 0.1 (3.6) 58.7 0.0 (2.7) (3.9) 26.3 26.9 83.4 85.0 1.9 86.9 0.0 86.9 Aug. 0.2 6.98 47.0 0.4 0.0 11.6 0.49 89.4 0.1 (3.3) 56.3 0.1 (2.4) 1.0 27.3 27.7 78.1 76.1 1.7 77.8 0.0 77.8 Sep. 0.6 4.99 48.5 1.0 0.0 10.2 0.43 59.9 0.3 (2.4) 58.1 0.2 (1.7) 5.0 32.2 32.2 62.4 48.6 1.1 49.7 0.0 49.7 Total, AFY 41.1 49.9 571 67.7 75.7 58.2 5.83 423.5 19.5 (23.7) 774.6 14.4 (17.5) 413.2 357.1 8.2 365.3 0 365.3 Base City Flow 0.510 mgd
Town Field Runoff Calculation Parameters LAA Information Pond Information Storage Soil Interception, inches 3 1 2 3 4 5 6 7
Percent Infiltration, saturated soil 0.4 Surface Area, acres 1.5 1.2 1.0 2.0 4.2 3.9 5.3 Percent Infiltration, unsaturated soil 0.6 Area, acres 57 5.6 130 3.1 Storage Volume, ac-ft 41.7 25.2 25.8 Min 2-month Rainfall for Saturation, inches 10 Crop Coefficient 1.00 1.00 0.88 -- Feb.-May. Perc. Rate, in/d 0.0 0.0 Max Precip Before Runoff Capture, inches 20 Irr. Efficiency 0.80 0.80 0.84 -- Jun.-Jan. Perc. Rate, in/d 0.0 0.0 (1) 1-in-100 year rainfall from Ione NCDC station (#044283) Legend for Cell Shading (2) Reference evapotranspiration from Plymouth CIMIS station (Station 227) - Value not directly used (3) = (Base City Flow) x (number of days in month) x 3.07 - Historical value used as reference (4) = 3.07 x (I&I in million gallons]. I&I in million gallons = 0.539 x (rainfall in inches) - 0.012, using linear equation developed in this TM. - Independent variable (manual input) (5) = (Column 1 - Column 2 - interception of 3 inches - infiltration in inches)/(12 inches per foot) x (surface area of Town Field, 57 acres). If Column 1 > 8 inches, then set value of Column 1 to 8 inches.

Infiltration in inches = (percent infiltration) x (Column 1 - Column 2 - interception of 3 inches). If the sum of Column 1 in the current and previous month >= 10 inches, percent infiltration is 0.4. Otherwise, percent infiltration is 0.6. (6) = (Column 9) x (Percentage of monthly COWRF influent flow discarded as backwash as defined in COGC TM) (see Attachment D) (7) Average monthly AWA backwash flow from 2021 to 2024 (8) = 0. Assume no CDCR flow.
(9) = Column 21 / (1 - COWRF filter backwash percentage as defined in COGC TM) (see Attachment D) (10) = (Column 1)/12 x (surface area of Ponds 1-4, 5.7 acres) (11) = (Column 2)/12 x (surface area of Ponds 1-4, 5.7 acres) (12) = Column 3 + Column 4 + Column 5 + Column 6 + Column 7 + Column 10 + Column 11 (13) = (Column 1)/12 x (surface area of Pond 5, 4.2 acres) (14) = (Column 2)/12 x (surface area of Pond 5, 4.2 acres) (15) = Column 12 + Column 13 + Column 14 - (Column 23 + Column 28 + Column 32 + Column 34) (16) = Column 16 of previous month + Column 15 of current month. If this is greater than the Pond 5 volume of 41.7 acre-feet, Column 16 is set to 41.7.

In September, Column 16 is set to 0 and the value in Column 34 is adjusted so that the formula in Column 15 predicts this value. (17) Monthly average storage volume in Pond 5 from 2019 to 2024 (18) Historical irrigation demand for COGC, from COGC TM (see Attachment D) (19) = [Column 1 - (Column 2 x crop coefficient of 0.88)]/12 x (surface area of golf course, 130 acres) x (irrigation efficiency of 0.84). If Column 19 < 0, then set Column 19 to 0. (20) = (Column 1 - Column 2)/12 x (surface area of golf course pond, 3.1 acres). If Column 20 < 0, then set Column 20 to 0. (21) = Column 19 + Column 20
(22) = Column 21 - Column 23
(23) = 0. Assume no flow from the City.
(24) = Column 22 + Column 23
Town
Field
City
Field
Golf
Course

86.9 77.8

49.7 365.3
Golf
Course
Pond
Treatment Percolation

10.1 53.7

77.8 0.0

0.0 0.0

9.3 0.0

0.0 2030 Flows: 1-in-100 Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 1 Month
(22)
Provided
by
Partners
988-50-24-10 15of16
City of Ione
Updated Water Balance
526
Section 13, Item J.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May
Jun.

Jul.

Aug.

Sep.

Total, AFY
Month
(25) (26) (27) (28) (29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (44) (45) (46) (47) (48) (49) Town Field Irrigation City Field Irrigation Percolation Pond 7 Avail for
Town
Historical
Demand
Theoretical
Demand
Provided
by City
Avail for
City
Historical
Demand
Theoretical
Demand
Provided
by City
System
Excess
Empty
Pond 5
Total
Flow to
Pond Rainfall Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Empty
Pond 7
Total
Flow to
Pond Evap.

Potential
Perc.

To/From
Storage
Cum.

Storage
Check for
System
Overflow
Discharge/
Store
Elsewhere

86.0 4.3 6.5 6.5 79.5 0.3 0.6 0.6 0.0 41 41.0 0.9 (1.4) 0.0 (26.5) 0.0 67 67.0 (1.1) 0.0 (25.2) 0.0 OK 91.8 100.3 1.2 0.0 0.0 100.3 0.0 0.0 0.0 0.0 69 69.0 2.3 (0.7) 0.0 70.6 25.8 44.8 (0.5) 0.0 25.1 25.1 OK 20.8 116.2 0.0 0.0 0.0 116.2 0.0 0.0 0.0 0.0 88 88.0 2.9 (0.5) 0.0 90.4 25.8 90.4 (0.4) 0.0 0.0 25.1 OK 92.1 143.1 0.0 0.0 0.0 143.1 0.0 0.0 0.0 0.0 110 110.0 4.2 (0.7) 0.0 113.5 25.8 113.5 (0.5) 0.0 0.0 25.2 OK 116.1

98.3 0.0 0.0 0.0 98.3 0.0 0.0 0.0 0.0 64 64.0 2.6 (0.9) 0.0 65.7 25.8 65.7 (0.6) 0.0 (0.0) 25.2 OK 67.0

95.4 0.0 0.0 0.0 95.4 0.0 0.0 0.0 0.0 60 60.0 2.6 (1.3) 0.0 61.3 25.8 61.3 (1.0) 0.0 (0.1) 25.1 OK 62.3

89.1 1.8 7.8 7.8 81.3 0.0 0.8 0.8 0.0 42 42.0 1.4 (2.0) 0.0 41.4 25.8 41.4 (1.5) 0.0 (0.0) 25.1 OK 41.0

93.5 0.6 28.4 28.4 65.1 0.3 2.8 2.8 0.0 24 24.0 0.5 (2.6) 0.0 21.9 25.8 21.9 (1.9) 0.0 0.0 25.1 OK 20.3

92.2 15.4 40.1 40.1 52.1 1.2 3.9 3.9 0.0 18 18.0 0.2 (3.2) 0.0 15.0 25.8 15.0 (2.3) 0.0 0.0 25.2 OK 12.8

86.3 13.5 44.6 44.6 41.7 1.2 4.4 4.4 0.0 11 11.0 0.1 (3.4) 0.0 7.7 25.8 7.7 (2.5) 0.0 (0.1) 25.1 OK 5.3

80.2 21.2 40.0 40.0 40.2 1.8 3.9 3.9 0.0 9 9.0 0.1 (3.1) 0.0 6.0 25.8 6.0 (2.3) 0.0 (0.0) 25.1 OK 3.9

83.8 11.7 25.9 25.9 57.8 1.8 2.5 2.5 0.0 23 23.0 0.3 (2.2) 0.0 21.1 25.8 21.1 (1.6) 0.0 0.0 25.1 OK 19.6 1164.2 69.7 193.4 193.4 970.8 6.8 19.0 19.0 0.0 559 559.0 18.2 (22.0) 0.0 488.1 67 556 (16.2) 0.0 (0.0) 553 Total Inflows: 559 Total Inflows: 556 Total Excess Water: 553 Total Outflows: 0 Total Outflows: 0
Legend for Cell Shading
(25) = (Column 16 of previous month) + Column 12 + Column 13 + Column 14 - Column 23. If Column 25 < 0, then set Column 25 to 0. - Value not directly used (26) Monthly average historical irrigation demand for Town Field from 2019 to 2024 - Historical value used as reference (27) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of Town Field, 57 acres) x (irrigation efficiency of 0.8). If Column 27 < 0, then set Column 27 to 0. - Independent variable (manual input) (28) If Column 25 < Column 27, Column 25. Otherwise, Column 27. (29) = Column 25 - Column 28. If Column 29 < 0, then set Column 29 to 0. (30) Monthly average historical irrigation demand for City Field from 2018 to 2023. (31) = [Column 1 - (Column 2 x crop coefficient of 0.32)]/12 x (surface area of City Field, 5.6 acres) x (irrigation efficiency of 0.8). If Column 31 < 0, then set Column 31 to 0. (32) If Column 29 < Column 31, Column 29. Otherwise, Column 31. (33) = (Column 16 from previous month) + Column 15 - (Pond 5 volume, 41.7 acre-feet). If Column 33 < 0, then set Column 33 to 0. (34) Manually entered to move water between Pond 5 and Pond 7 to approximately match historical Pond 5 volumes. Positive values indicate flow from Pond 5 to Pond 7. Negative values indicate flow from Pond 7 to Town Field/City Field. (35) = Column 33 + Column 34
(36) = (Column 1)/12 x (surface area of Pond 7, 5.3 acres) (37) = (Column 2)/12 x (surface area of Pond 7, 5.3 acres) (38) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 7, 5.3 acres). Percolation rate set to 0 inches per day. (39) = Column 35 + Column 36 + Column 37 + Column 38 - Column 41 (40) = Column 40 of previous month + Column 39 of current month. If this is greater than the Pond 7 volume of 25.8 acre-feet, Column 40 is set to 25.8. If this is < 0, Column 40 is set to 0. In August, Column 40 must be <= 0 in order for the balance to work. (41) Manually entered to move water between Pond 7 and Pond 6. Positive values indicate flow from Pond 7 to Pond 6. Negative values indicate flow from Pond 6 to Pond 7. (42) If Column 40 >= Pond 7 volume of 25.8 acre-feet, Column 42 = (Column 40 of previous month) + Column 39 + Column 41 - 25.8. If Column 40 < 25.8, Column 42 = Column 41. (43) = (Column 1)/12 x (surface area of Pond 6,3.9 acres) (44) = (Column 2)/12 x (surface area of Pond 6, 3.9 acres) (45) = (percolation rate in inches per day)/(12 inches per foot) x (number of days in month) x (surface area of Pond 6, 3.9 acres). Percolation rate set to 0 inches per day. (46) = Column 42 + Column 43 + Column 44 + Column 45
(47) = Column 47 of previous month + Column 46 of current month. If this is greater than the Pond 6 storage volume of 25.2 acre-feet, Column 47 is set to 25.2. If Column 47 < 0, set to 0. In July, Column 47 must be <= 0 in order for the balance to work. (48) If (Column 46 of current month) + (Column 47 of previous month) > Pond 6 storage volume of 25.2 acre-feet, Column 48 = "Overflow". Otherwise, Column 48 = "OK". (49) Manually entered to move water between Pond 6 and New Storage/Disposal Site to ensure pond storage capacity is not exceeded.

0.0 0.1

0.2 13.4

1.1 0.4

0.1 3.1

1.9 1.9

0.7 1.7

2.1 (43)
Percolation Pond 6
Rainfall
2030 Flows: 1-in-100 Rainfall Year Water Balance for City of Ione Wastewater Treatment Plant, No Percolation, Crop Coefficient of 1 988-50-24-10 16of16
City of Ione
Updated Water Balance
527
Section 13, Item J.

Outlook
Gold Rush Ranch specific plan area
From Robin Peters <[email protected]>
Date Wed 3/5/2025 1:01 PM
To Tom DuBois <[email protected]>
Cc Claire Gunselman <[email protected]>; Julia Sierk-Zanze <[email protected]>; Susan Feist <[email protected]>; James Swift <[email protected]> Good evening Tom and members of the City Council,
I read with interest the background information for Item 9C on tonight’s City Council agenda. I understand the item is agendized for information only – as a way for the applicants to read the community tea leaves - so I thought a few big-picture comments might be of some help.

General comments about the original approvals
Many will recall that the original GRR project split the community into two camps: those who had no interest in nor use for the magnitude of the proposed development and its attendant impacts, and those who accepted certain impacts with the understanding that the way the project was ultimately conditioned would bring badly-needed or at least positive amenities (a new wastewater treatment plant, a golf course community, etc.). The only reason the City Council ultimately approved the project and, later, the referendum was unsuccessful, is that it was clear in the conditions that the project couldn’t move forward without providing certain amenities up front.

In effect then, there was little risk to the City because the project could never reach the point where impacts were generated without first constructing the amenities. This arrangement was not a result of happenstance, but rather of painstaking work by the City over a period of several years, through countless meetings, to make certain the City would be made whole in the end. Most folks know that a developer’s first responsibility to his shareholders is to kick conditions, obligations, infrastructure, etc. forward – to a future phase – to a phase that, alas, is never reached. Today, it is the City Council’s responsibility to its constituents to make certain that isn’t allowed to happen in this instance.

Consistency with the Gold Rush Ranch Specific Plan (GRR-SP) The GRR-SP (Attachment J) very specifically delineates conditions that apply to: all projects and activities within the GRR-SP area, to large lot subdivisions within the GRR-SP area, and to subsequent small lot subdivisions within the area. It would appear that this developer is skipping the large-lot approach, at least for the time being, and moving directly to the first small-lot subdivision. In this case then, all of the conditions in Attachment J, Sections 1.0 and 3.0 must be placed on this tentative small lot subdivision map, if approved.

Condition 1.14 is of particular interest … compelling construction of a new wastewater treatment plant before the issuance of any residential building permits.

The slide presentation in tonight’s packet indicates that the development wishes to proceed by “… following the current specific plan.” Yet the phasing is different, proposed roadway alignments are different, the golf course is being pushed to a future phase, and there is no mention at all of constructing a new wastewater treatment plant (only of contributing to a WWTP, and then only in a future phase). No part of those proposals are consistent with the GRR-SP and therefore cannot be approved as presented.

Wastewater capacity
The subdivision proposal currently on the table appears to be moving forward on the assumption that it will be allowed to consume the entirety of our current wastewater treatment plant’s capacity – the reason only 150 homes are currently being proposed. This is in stark contrast with the strict language of the GRR-SP, but also with the intent of a number of the wastewater conditions. The GRR-SP was approved by the City Council with the understanding that the project would not only replace its aging wastewater treatment plan with a new 528 Section 13, Item K.
one, but to provide additional capacity beyond its current 0.48 MGD. Any tentative subdivision map application within the GRR-SP area that proposes instead to consume the City’s remaining treatment plant capacity, rather than replace and augment it as required by the GRR-SP, should be considered dead on arrival.

Golf Course
It’s difficult to tell from the slide presentation, but it appears that the 17 acres of community park dedication sits squarely on a portion of the golf course and also on a portion of another village. Say what you want about the viability of golf courses in today’s market, but an up-front golf course is baked into the GRR-SP, so any proposal that has the potential to negatively affect implementation of a golf course would be inconsistent with the GRR-SP.

Allen Ranch Road-Ampine Road intersection improvements
The slide presentation indicates that Allen Ranch Road would be extended to SR 104 at Ampine Road.

Condition 1.36(a) requires that intersection improvements, possibly including signalization, are required prior to issuance of the first building permit within the GRR-SP area. These improvements don’t appear in the slide presentation but are required as a condition of approval of any small lot subdivision map.

Grading
The slide presentation identifies grading as a “Key Consideration.” The snippet of grading included in the slide presentation is clearly mass grading, which is not consistent with the GRR-SP for this portion of the specific plan area. Grading and grading limitations occupied a great deal of time and consumed a great deal of energy during the original approval process, and compliance with the GRR-SP grading standards must be demonstrated.

Please send the message to the developer this evening that the City Council expects any development project within the GRR-SP area to demonstrate consistency with the entirety of the adopted GRR-SP. And please enter these comments into the public record for tonight's meeting.

Thank you for your time and consideration.

Robin Peters
146 Badger Road
Sutter Creek
529
Section 13, Item K.
18 Main St., Sutter Creek, CA 95685 • Telephone: (209)267-5647 • Fax: (209)267-1655 • TTY: 711 The City of Sutter Creek is an equal opportunity service provider and employer Tom DuBois
City Manager
City of Sutter Creek
18 Main Street
Sutter Creek, CA 95685
March 4, 2025
John Gedney
Executive Director, ACTC
117 Valley View Way
Sutter Creek, CA 95685
Dear John:

As you know, neither of us were in our current positions when the SR 104- Prospect Drive/Bowers Drive Realignment was constructed. I have been attempting to reconstruct what occurred and who is legally liable for past expenses, if anyone.

I have talked to the Sutter Creek City Attorney, former City Manager Sean Rabe and past City Council members. Construction appears to have occurred after it was known that the Gold Rush Developers were not proceeding with the project. If that is true, it raises the question why was the project prioritized and funded at that time, with no developer involvement? I’ve been told that it was done primarily to benefit Martell by aligning with Prospect Court. This is all secondhand information, so please correct me if you have a better source.

The City cannot locate any legal agreement or contract that confirms that the City of Sutter Creek owes the funds. When the question was asked at the Feb 18th RTMF Meeting whether the $1,482, 127 was owed by the City, the response was that it is not owed by the City but was a pass through to the previous developer (which was Gold Rush Golf LLC). That developer went bankrupt and no longer exists. No lien was put against the property which was then sold to the current development group.

There was a development agreement with conditions of approval with Gold Rush Golf LLC, but that development agreement expired in 2019. Attachment J, Conditions of Approval had section

1.37, last paragraph, which said the developer would reimburse ACTC if funds were expended.

One would expect that when ACTC spent funds in advance of the project, with the expectation that Gold Rush Golf LLC or another developer would repay them, that contracts and documentation would be put in place at that time. Those contracts would specify in greater detail 530
Section 13, Item K.
2 than the paragraph in the conditions of approval the project details, timing and repayment schedule with that developer before construction commenced. That does not appear to have occurred.

The new development group, Sutter Creek Land Advisors, has submitted an application for a 150-home subdivision, in accordance with the specific plan. This smaller scale project is more in line with development rates in 2025 than the Gold Rush Golf LLC’s first phase which proposed 500 homes, a golf course, a hotel and commercial buildings in its first phase. Sutter Creek Land Advisors are not asking for any zoning exceptions and have agreed to comply with the City’s Specific plan in future phases, including road improvements.

In regards to construction from many years ago, they maintain they are not responsible for the old debt, with no lien on the property when they purchased it. I am attaching a letter from them that outline their position. However, in the interest of advancing the project and putting this historic issue behind them, they are proposing to partially repay the fees overtime as the project is developed. The 150 homes are on smaller, 7000 sq ft lots with the expectation this housing will be more affordable market rate housing. Given the smaller project scope, economic analysis suggests its impractical to expect large upfront payments.

I’d ask the board to consider their offer for the following reasons:
• Establishing the legal basis to collect the debt appears murky and potentially not legally defensible
• No one wants to get into a legal battle in any case
• The roadway has depreciated over the years, and collecting more than 2/3 the amount is a good outcome
• If the project is successful and moves on to additional phases, the City and County will benefit from additional roadway improvements
This is an unusual situation for all parties involved. I am hopeful that this issue can be resolved between ACTC and Sutter Creek Land Advisors. The City of Sutter Creek has not yet deemed the application complete; this is one of a few remaining open issues.

Apologies my schedule does not allow me to attend the meeting on March 6th.

Best,
Tom DuBois
City Manager
City of Sutter Creek
CC: ACTC Board
Attachments: 1
531
Section 13, Item K.
532
Section 13, Item K.