Patterson City Council
July 21, 2026

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pursuant to the City’s Zacharias & Baldwin Ranch Master Plan (“Master Plan”). In 2022, the City certified an Environmental Impact Report (“EIR”) finding that Master Plan development would not result in significant impacts to groundwater supplies.2 Specifically, the Master Plan EIR found that the Master Plan will decrease water demand overall by 60 percent (some 3,225 afy) compared to the prior agricultural uses. (Draft EIR, pp. 3.9-23 to 3.9-26, 3.15-8; Final EIR, p. 3-70.) The Master Plan EIR cited and relied on the City’s UWMP and the Master Plan’s Water Supply Assessment, both of which find that Patterson has over three times the water needed to meet projected demand. (Draft EIR, pp. 3.15-20 to 3.15-21, 4-13 to 4-14; Final EIR, pp. 3-39 to 3-40; see also Draft EIR, Appendix I, pp. 3-4 and 4-5.)
In May 2024, the Master Plan area was annexed into the City limits. The Keystone Project and one other Master Plan development—Lakeside Hills—were identified in the City’s Housing Element as two key projects needed to meet the City’s Regional Housing Needs Allocation (“RHNA”) of 3,716 units. In the Housing Element, the City also committed to “only charge developers their respective fair share” for necessary infrastructure improvements, “facilitate the phasing of infrastructure to enable timely residential development to meet the City’s RHNA,” “provide flexibility in permit timing relative to needed infrastructure improvements,” and “coordinate and collaborate with property owners and developers . . . to accelerate housing development.” (Housing Element, pp. 3-17 to 3-20.)3 The Housing Element commits the City to implement these programs and to monitor effectiveness by reporting to the State on whether it has issued 3,503 residential building permits by June 2027. (Housing Element, p. 3-19.) In contrast, the UWMP claims that demands from Master Plan development are not assumed to first come online until 2029-2030. (UWMP, p. 7-8.)
Notwithstanding the foregoing, the City Council denied Keystone’s housing Project on April 1, 2025 because Keystone would not agree to the City’s demand that it: advance the estimated $20 million cost of a City recharge facility (identified in the GSP as financed by City and State funds 2 In a recent case, the Court of Appeal reaffirmed that “an analysis of water supply in an environmental document may incorporate by reference information in a water supply assessment, urban water management plan, or other publicly available sources” and that “long-term local water planning is not a burden that must be taken up anew, for CEQA purposes, each time a development is proposed; rather, cities and counties may rely on existing urban water management plans, so long as the expected demand of the [project] was included in the water management plan’s future demand accounting.” (City of Vallejo v. City of American Canyon (2026) 117 Cal.App.5th 1112, 1128, 1131 citing CEQA Guidelines § 15155(d) and Vineyard Area Citizens for Responsible Growth v.

City of Rancho Cordova (2007) 40 Cal.4th 412, 446-447.) 3 The State Department of Housing & Community Development (“HCD”) stated that these programs “are especially crucial to the success of the housing element and the City’s ability to regain and maintain housing element compliance.” (See HCD’s December 2, 2025 letter to the City.) Packet Pg. 938
Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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and to be completed by 2040), delay construction of its Project for at least five years pending the recharge basin’s development, and purchase surface water to “offset” its minimal water demand of 138 afy. The City claimed that the GSP compelled its actions and blamed the State for changing the water supply circumstances applicable to the Master Plan. In reality, nothing in the GSP purports to justify the City’s actions.

Keystone sued the City over its unlawful denial of the Project. (Keystone Ranch, LLC v.

City of Patterson, Stanislaus County Superior Court Case No. CV-24-003269.) On May 11, 2026, the Court (Honorable Judge Sunny Sandhu presiding) issued its Tentative Ruling and Proposed Statement of Decision in favor of Keystone and against the City (the “Ruling”). In the Ruling, the Court found that the City violated, among others, the Housing Accountability Act (“HAA”) by denying the Project without making the findings required by the HAA. The Court also found that the City violated the Housing Crisis Act by imposing a moratorium or similar restriction on housing development. The Court squarely rejected the City’s claim that its denial of the Project was justified by “changed circumstances” associated with the GSP. See Ruling, page 13:

The relevant facts established by the record, and largely undisputed, defeat the City’s supplemental review argument. The Project’s estimated potable water demand is approximately 138 afy. The City’s Urban Water Master Plan documents a sustainable yield of 10,000 to 12,500 AFY. At the time of the April 1, 2025, hearing, the City was pumping approximately 3,086 AFY—approximately one-quarter of its documented sustainable yield.4
The Court ordered the City to set aside its denial of the Project and reconsider the Project application within 90 days of entry of the writ, applying only policies that were in effect at the time of vesting. Keystone’s vesting was first accomplished by its submittal of a Senate Bill 330 Preliminary Application on November 6, 2023. Neither the GSP nor the Northern Delta-Mendota Region Pumping Reduction Plan (“PRP”) were in effect at the time of the Project’s vesting.

Further, the Court explicitly prohibited the City from imposing as conditions on the Project:
(1) a requirement that the Del Puerto Creek recharge project be constructed and completed before the issuance of any building permit in the Master Plan area and (2) a blanket requirement that Keystone or other Master Plan developers purchase surface water to offset groundwater pumping. (Ruling, pp. 18-19.)
4 (See also Ruling, p. 18 [noting that the City’s “path to a lawful denial in this case is narrow” citing the City’s water supply data—a sustainable yield of approximately 10,000 to 12,000 AFY against current pumping of approximately 3,086 AFY and a Project demand of only 138 AFY].) Packet Pg. 939
Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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2. The UWMP Conflicts with the GSP.

The UWMP claims that the GSP imposes “pumping limitations” that reset the City’s local sustainable yield to 2,626 afy. (UWMP, pp. ES-1, 2-2, 6-3, Table 6-10, 7-1, 7-8; see also UWMP, p. 6-6 [claiming without any citation to authority that “groundwater sustainability for the City is now managed through basin-wide Sustainable Management Criteria and pumping cutback requirements, which are regulated by the PRP, rather than a fixed local safe yield value.”]) The GSP does nothing of the sort. Instead, the GSP establishes a flexible, basin-wide management system designed to achieve groundwater sustainability by 2040, which includes a multitude of measures in addition to potential pumping reduction actions. To the extent the GSP requires the City to reduce pumping by 2030, it is by a modest amount, which City Staff admitted it could achieve through conservation and related measures.

As a preliminary matter, the GSP lists the City’s water source exclusively as groundwater and acknowledges that groundwater extractions in the City are projected to double from current levels through 2045. (GSP, Appendix J, pp. viii, 14, and Figure 4-30.) It also plainly identifies the recharge basin project as a City project to be funded by City and State funds with an implementation timeframe of 2040. (GPS, Chapter 15, Table PMA-1, p. 9 and Table PMA-2, p. 5.)
Moreover, pumping reduction is just one of 50 or so programs and management actions designed to achieve sustainable use of the basin’s groundwater resources by 2040. (Water Code § 10727.2(b); GSP, p. 217; see also GSP, Chapter 15.) Pumping reduction was only intended to achieve 30 percent of the overdraft “fix.”5 (GSP, p. 18.) The remaining 70 percent is to be achieved through specified water supply projects and management actions. (Id.; see also GSP, pp. 299-302 [listing the PRP as just one of approximately 50 projects and management actions developed to sustainable manage the basin’s groundwater resources].) 5 To the extent that that the Subbasin is deemed to be in overdraft, it is mostly due to water extracted for agricultural uses elsewhere in the basin. (Delta-Mendota Subbasin Water Year 2025 Annual Report [“Annual Report”], p. 1-14 [states that domestic and related uses comprise only one percent (1%) of total water use in the Subbasin].) The Annual Report can be found at the following link and is incorporated herein by reference: https://www.maderacountywater.com/wpcontent/uploads/2026/04/5-022.07_WY_2025_Delta_Mendota_Annual_Report_compressed.pdf Further, the estimated overdraft conditions differ significantly throughout the Subbasin, with the Northern portion (including Patterson) being in better condition than other parts. (Annual Report, p. 1-19; see also https://storymaps.arcgis.com/stories/b3886b33b49c4fa8adf2ae8bdd8f16c3 [State’s monitoring of groundwater levels shows increased levels of groundwater in and around Patterson].)
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Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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Additionally, the PRP was never adopted by the City nor did it undergo any form of environmental review pursuant to the California Environmental Quality Act (“CEQA”). Instead the PRP was developed by consultants working for the Northern Delta Mendota Region Management Committee (“Committee”). Per the GSP, the Committee “may recommend policies or programs to the [Groundwater Sustainability Agency or “GSA”] that the GSA could in its discretion, adopt to remedy the existence of [a Minimum Threshold] exceedance and to avoid undesirable results.” (GSP, p. 325 [emphasis added].)
The GSP confirms the uncertainty of the data used and that “further calibration” of the model is needed to successfully implement the PRP. (GSP, pp. 327-328.) The PRP further states that pumping reduction numbers will be “adjusted and adopted based on model updates and the availability of additional data and measurements.” (PRP, pp. 1, 3.) Such calibration has not yet occurred. (Annual Report, p. 1-17 [Model has not yet undergone calibration, thereby likely overstating the amount of overdraft in the Subbasin, noting additional data collection and targeted calibration efforts are needed particularly in the lower aquifer and to improve confidence in modeled storage change estimates]; see also p. 2-17 [noting insufficient monitoring data to allow for assessment of land subsidence], p. 1-9 [noting insufficient information relative to sustainable yields] and Tables 1-2 and 1-4 at pp. 1-8 and 1-15 to 1-16 [listing measurement accuracies as “Unknown”].)
The PRP also states that if a specific agency’s target is not met, it will keep its pumping to within its local sustainable yield. (GSP, pp. 321, 325; PRP, p. 15.) This shows that the pumping target and the local sustainable yield are not the same thing. The City’s current pumping of 3,086 afy is approximately one-fourth of its local sustainable yield of 10,000-12,000 afy. Thus, in order to be consistent with the GSP and the PRP, the UWMP must be revised to reflect the local sustainable yield.

At the December 10, 2025 Committee meeting, members complained that their assigned pumping reduction numbers were based on “garbage in, garbage out” assumptions, with the City’s Water Resources Manager asking if the PRP reduction targets are “actual true solid numbers that can be backed up” and the Committee’s consultant recommending that pumping reduction targets be changed from fixed numbers to percentages to be derived from more accurate data. In other words, six months ago, the City’s Water Resources Manager questioned whether the City’s pumping reduction target could be substantiated. Now, without any additional data or supporting analysis, the City’s UWMP cites the 460 afy reduction number as if it is a universal truth.

In terms of its contents, the PRP calls on GSAs to reduce pumping across its total area of responsibility in general but does not prohibit approval of development and additional groundwater demands. The GSAs must reduce overall pumping by targeting areas where minimum threshold (“MT”) exceedances occur. Thus, consistent with the Sustainable Groundwater Management Act (“SGMA”) framework, pumping reductions are targeted at areas where MTs are exceeded, which Packet Pg. 941
Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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ensure that pumping restrictions are actually linked to achieving sustainability goals.6 According to the Annual Report, groundwater elevations throughout the Subbasin were largely above their respective MTs with no undesirable results relative to groundwater levels or storage observed. (Annual Report, p. ES-3.) Similarly, for the Northern Delta-Mendota group, there were no MT exceedances in Water Year 2025. (Annual Report, p. 2-8.) Further, after denying Keystone’s Project, the City inconsistently approved four other major developments, including over five million square foot of warehouse and logistics center space without conditions prohibiting development until the City’s recharge basin was constructed or mandating purchase of surface water supplies.
7 Graphics depicting the City’s patently arbitrary
and unequal treatment of Keystone’s Project compared to these projects is attached hereto as Exhibit B.

In addition, none of the other GSAs included in this GSP and its pumping reduction policies have followed the City’s precipitous actions or taken this extreme position that it calls for an immediate cessation of development without a commitment to offset groundwater usage. For instance, in October 2025, the Stanislaus County Board of Supervisors approved plans and specifications to increase groundwater demand in the Delta-Mendota Subbasin through new well improvements and related water facilities for the Crows Landing Industrial Business Park (“CLIBP”). This portion of the County is covered by the same PRP as Patterson. The CLIBP consists of a 1,528-acre site planned for more than 14 million square feet of business and industrial 6 These points are explained in an April 19, 2026 letter from Robert Donlan, a preeminent lawyer with the firm of Wanger, Jones & Helsey, who specializes in water law. A true and correct copy of Mr. Donlan’s letter is attached hereto as Exhibit A. 7 (See Patterson Logistics Center-a 1.1 million square foot distribution center approved by the Planning Commission on June 12, 2025:
https://www.pattersonca.gov/AgendaCenter/ViewFile/Agenda/_06122025-1359; Project Zach-a

3.2 million square foot warehouse and distribution center approved by the Planning Commission on June 26, 2025:
https://www.pattersonca.gov/AgendaCenter/ViewFile/Agenda/_06262025-1364 and https://www.pattersonca.gov/AgendaCenter/ViewFile/Agenda/_06262025-1365; and West Commerce Park-a 1.1 million square foot warehouse and distribution center approved by the City Council on August 28, 2025:
https://www.pattersonca.gov/AgendaCenter/ViewFile/Agenda/_08282025-1383 ; see also Villages of Patterson-Olive Avenue-a residential subdivision of 162 lots approved by the City Council on August 19, 2025:
https://pattersonca.iqm2.com/Citizens/FileOpen.aspx?Type=1&ID=1476&Inline=True.) We hereby incorporate into the record of proceedings for this matter, the agendas, staff reports, minutes, video recordings, resolutions/ordinances, environmental documents, correspondence, and related materials for these City projects.

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Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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space, a 370-acre public-use airport, and over 14,000 living wage jobs. No conditions or limitations restricting development due to the GSP or PRP were imposed on the CLIBP, which is located approximately six miles south of Patterson.8 The cities of Los Banos, Dos Palos, and Newman have likewise approved major housing development projects since approval of the GSP without requirements that new development offset its groundwater usage with alternative water supply sources and not proceed with development until such sources are secured. 9 The UWMP’s misrepresentation of the GSP as a pretext for imposing a de facto moratorium on new housing development is not only wrong factually (as detailed above), it is wrong legally. It converts a long-term aspirational groundwater planning framework into an immediate land use prohibition weapon, contrary to both the text and intent of SGMA as well as the Planning & Zoning Law. (See, e.g., Water Code § 10726.8, subd. (f) [neither SGMA nor a GSP “shall be interpreted as superseding the land use authority of cities and counties, including the city or county general plan, within the overlying basin.”]; subd. (a) [SGMA does not limit “the authority granted to a local agency under any other law.”]; Gov. Code § 65858 [development moratorium must be approved by a four-fifths vote of a local agency’s legislative body upon a 8 We hereby incorporate into the record for this matter, the agendas, staff reports, minutes, video recordings, resolutions/ordinances, environmental documents, correspondence, and related materials for CLIBP: https://www.stancounty.com/bos/agenda/2025/20251014/DIS01.pdf. 9 (See, e.g., approvals by: (1) City of Los Banos Planning Commission of San Luis Estates-a 96 unit residential development approved December 11, 2025: https://losbanos.org/wpcontent/uploads/2025/12/PC_Agenda_Packet_20251211_adjpcmtg.pdf, One Tree Cottages-a 58 unit residential development approved February 19, 2025: https://losbanos.org/wpcontent/uploads/2025/02/CC-Agenda-Packet-2.19.25-revised2.pdf, Snow Goose-a 25 townhome development approved October 2, 2024: https://losbanos.org/wp-content/uploads/2024/09/CCAgenda-Packet-10.2.24.pdf, Overland Trail Subdivision-a 50 unit residential development approved March 4, 2026: https://losbanos.org/wp-content/uploads/2026/02/CC-Agenda-Packet3.4.26-1.pdf, and Villages VI Subdivision-a 30 unit residential development approved February 4, 2026: https://losbanos.org/wp-content/uploads/2026/01/CC-Agenda-Packet-2.4.26.pdf, (2) City of Dos Palos City Council of Rainbrook Run-a 102 unit residential development approved August 19, 2025: https://dospalos.gov/government/documents/meeting-documents/mayorcouncil-meeting/2025-city-council-meeting-documents/2025-agendas-city-council/306-agendapacket-august-19-2025/file, and (3) City of Newman City Council of Mattos Ranch-a mixed use commercial and residential project approved December 10, 2024:
https://cityofnewman.gov/~documents/city-council-elected-officials-elections/city-councilagendas/2024-city-council-agendas/12-10-2024-city-council-agenda/?layout=file.) We hereby incorporate into the record for this matter, the agendas, staff reports, minutes, video recordings, resolutions/ordinances, environmental documents, correspondence, and related materials for these projects.

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Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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finding that there is a current and immediate threat to the public health, safety, or welfare]; see also Water Code § 350 [water shortage emergency must be approved by governing body of a distributor of a public water supply based on a finding that there are insufficient supplies for human consumption, sanitation, and fire protection].)

3. The UWMP Conflicts with the City’s Operational Yield Study.

In its 2020 UWMP, the City relied on an Operational Yield Study (“OYS”) prepared to estimate the volume of groundwater that the City could extract from the underlying groundwater basin without impacting current groundwater pumping infrastructure and without significantly impacting the use of groundwater resources in the area surrounding the City’s Sphere of Influence.

The OYS was designed to provide information required to make decisions on future reliance on groundwater as a supply for the City. The OYS concludes that “the City could increase its pumping capacity to the range of 10,000 to 12,000 AFY without impacting current groundwater pumping and without significantly impacting the use of groundwater resources in the area surrounding the City’s Sphere of Influence.” (Master Plan EIR, p. 3.9-24.)
Nothing in the GSP or PRP alters the scientific-based evaluation of the City’s local sustainable yield of 10,000-12,000 afy. In its proposal to prepare the UWMP, the City’s consultant stated that it did not anticipate significant changes from the 2020 UWMP. (April 2, 2026 letter from Woodward & Curran to City of Patterson.) The 2020 UWMP relied on the OYS which found the City had a sustainable yield of 10,000 to 12,000 afy. The 2025 UWMP does not rely on any operational yield study and claims the City has sustainable yield of only 2,626 afy. This is a significant change, that is not supported by substantial evidence in the record.

The City’s sustainable yield of 10,000-12,000 afy has not changed. It continues to be relied on by the City in approving other projects after denying the Project. For instance, the City relied on an August 2025 Addendum to a 2012 EIR for the West Commerce Project, a 1.1 million square foot warehouse & distribution center, finding that it would have no new impacts to groundwater supplies or conflicts with the GSP. (West Commerce Project Addendum, p. 123 [noting the project “would result in an annual water demand which is within the limits of estimated demand considered in the Water Master Plan. Therefore, the proposed Project would not conflict with implementation of a sustainable groundwater management plan.”]; and p. 169 [cites to the existing UWMP’s safe yield figure and notes that the City will not exceed that level with the project.].) As recently as last week, the City’s Planning Commission relied on a May 2025 Addendum to a 2012 EIR for Project Zach, a major warehouse & distribution center when approving a modified version of that project. (See June 11, 2026 Planning Commission Agenda at Packet Pg. 944
Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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https://www.pattersonca.gov/AgendaCenter/ViewFile/Agenda/_06112026-1474.)10 Like the West Commerce Project Addendum, the Project Zach Addendum found that the project would not result in new or more severe impacts to groundwater resources and was consistent with the citywide water demand projections of 12,000 afy. (Project Zach Addendum, p. 49; see also pp. 65-66.)

4. The UWMP Fails to Meet the Requirements of State Law.

Under Water Code Section 10630.5, every UWMP “shall include a simple lay description of how much water the agency has on a reliable basis, how much it needs for the foreseeable future, what the agency’s strategy is for meeting its water needs, the challenges facing the agency, and any other information necessary to provide a general understanding of the agency’s plan.” Similarly, Water Code Section 10631(b)(1) requires a UWMP to include a “detailed discussion of anticipated supply availability under a normal water year, single dry year, and droughts lasting at least five years, as well as more frequent and severe periods of drought, as described in the drought risk assessment.” The City’s proposed UWMP fails to meet these requirement by relinquishing its decision making authority to the GSP and the City’s faulty interpretation of the GSP and PRP. Specifically, the UWMP fails to describe how much water the City has access to on a reliable basis, and instead, simply assumes that the PRP and GSP categorically restrict the City’s water rights. This is incorrect.

When establishing the amount of water the City has on a reliable basis, the City should determine the potential safe yield from the basin underlying the City, and use that figure as the available amount of water. (GSP, pp. 321, 325 [noting that groundwater pumpers must keep pumping within their local safe yields]; PRP, p. 15.) While the GSP, and PRP, should be discussed in the UWMP, they should not be viewed as creating some sort of de facto limit on groundwater production. The statutes require the City to actually describe the amount of water to be pumped by the supplier. As such, the UWMP should be revised to reflect the true amount of groundwater that will be pumped to service the City’s existing needs, along with the City’s projected future needs irrespective of the GSP and PRP.
11 10 We hereby incorporate into the record for this matter, the agendas, staff reports, minutes, video recordings, resolutions/ordinances, environmental documents, correspondence, and related materials for the modifications to Project Zach.
11 Under the City’s current reasoning, the City is imposing an immediate prohibition to below 3,000 afy on existing pumping needs. Does this mean that the City will be prohibiting existing water users (agricultural and other uses alike) from pumping beyond a certain amount? If the City’s position is true, then the UWMP must be revised to explain the discrepancy between the City’s actual water demand and use (greater than 4,000 afy), and the City’s 2,626 afy figure. There is no such an analysis in the UWMP, which is a fatal flaw that must be corrected.

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Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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In addition to the fact that the City has failed to describe the City’s actually anticipated water supply, the UWMP’s blind reliance on the PRP’s figures is also problematic because there is no evidence in the record that supports the City’s proposed safe yield and other figures. For example, the UWMP’s proposed safe yield at 2,626 afy is supposedly based on a 460 afy reduction to the City’s average water use for Water Year 2019 to Water Year 2023, which was estimated at 3,086 afy. (See PRP, Table 6-10.)
However, that analysis showing how the City reached this 3,086 afy figure is not provided anywhere, and there appears to be no evidence to support that figure. Additionally, even assuming that figure is correct, it is not consistent with the requirements of the GSP, which states that groundwater pumping is to be reduced from the average pumping from the overdraft evaluation period (Water Year 2003 to 2023). (See, e.g., GSP, p. 321.) Perhaps more fundamentally, the record is filled with information and statements admitting that the figures discussed in the GSP and the PRP are inaccurate and of no real qualitative value. Accordingly, the City’s reliance on the 2,626 afy value is misplaced and not supported by any credible evidence. The UWMP indicates that the City is currently pumping 4,033 afy from the lower aquifer with none of the alternative water supply programs in place. (UWMP, p. 6-5.)
The UWMP must be revised to describe the City’s actual anticipated supply of water, including groundwater, and not just rely on the PRP to create a fabricated supply amount that has no basis in reality.

5. The UWMP Incorrectly Analyzes the Impacts of the PRP on the Availability of the City’s Groundwater Supply.

Even assuming for the sake of argument that the PRP did impose a requirement that the City reduce its pumping and/or demand by 460 afy (it does not for the reasons stated above), the alleged obligation either has already been satisfied by the City and/or would only apply to 2030.

Furthermore, when implementing the PRP, the City and other GSAs have wide discretion as to how it will meet those goals.

First, it appears that the City can easily satisfy the pumping reduction requirement through the implementation of demand reduction measures. For example, per the City’s FY 25-26 Annual Water Supply & Demand Assessment Shortage Report (June 2025, Woodard & Curran) (“Supply and Demand Report”), the City has already implemented a series of demand reduction measures, and has projected an annual decrease in demand by 463 afy. (See Supply and Demand Report, Table 4-1.) As such, the City (a) has already met the requirements of the GSP (which recommends either pumping reductions or other measures to increase groundwater storage within the basin), and (b) can clearly continue to implement these same measures on an annual basis to continue to meet this demand reduction. The UWMP should be revised to reflect the fact that the goals of the PRP have Packet Pg. 946
Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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already been met, and can continue to be met by the City’s ongoing implementation of demand reduction measures.

Second, the UWMP incorrectly assumes that the PRP will require the same reduction to 2,626 afy until 2040. (See PRP Table 6-10.) The PRP on its face, and per the GSP, is only contemplated to be implemented until 2030, with 2030 being the year with the greatest demand reduction if needed. (See, e.g., GSP, Table PMA-2, p. 3 [noting that accrual of expected benefits to basin is to occur by 2030]; Table PMA-1, p. 6 [noting that pumping reduction plans to have been implemented by 2030].) The City’s UWMP instead concludes that the pumping reductions will remain in effect until 2040. This is improper, as the PRP can only apply until 2030 at the latest.

Accordingly, at a minimum, the UWMP must be revised to reflect what the local sustainable yield will be starting in 2031 and onwards (without regard to the PRP). (See Water Code § 10631 [requiring detailed discussion of water supply availability for five-year increments for a total of 20 years].)
As explained above, the City’s UWMP is based on the fatally flawed assumption that the GSP and/or the PRP create a mandatory duty on the City to restrict groundwater pumping to a certain level, regardless of local conditions. This is incorrect for the reasons outlined above. Furthermore, other groundwater sustainability agencies subject to the GSP have not reached the same draconian conclusion.

For example, the Aliso Water District GSA Pumping Reduction Plan recognizes that the pumping reduction goals are aspirational, and includes pumping reduction requirements that can “adapt to the needs of the basin,” and that the pumping reduction “targets” will be adjusted as the Sustainable Management Criteria are evaluated. (See Aliso Water District GSA Pumping Reduction Plan, pp. 6-7.)12 The Farmers Water District Pumping Reduction Plan goes one step further, and simply says “FWD will not contribute to the overall reduction between 2025 and 2030.” (Farmers Water District Pumping Reduction Plan, p. 3.) Similarly, the Zone 2 Pumping Reduction Plan recognizes that some of the pumping reduction will come from the introduction of efficiency requirements. (See Zone 2 Pumping Reduction Plan, p. 9.) Indeed, even the PRP that is applicable to the City, recognizes that the implementation of the reductions can be accomplished via different means, and that the targets will change over time. (Northern Delta-Mendota Region Pumping Reduction Plan, p. 3 [“Pumping reduction under this plan may be adjusted and adapted based on model updates and the availability of additional data and measurements.”].) In short, neither the GSP or the PRP require the City to actually reduce pumping per se. (See also, GSP, p. 321 [“As discussed above, the GSAs will collectively reduce total groundwater pumping by an estimated 12 Each of the relevant pumping reduction plans were included in the Annual Report, as appendixes.

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Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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42,000 AFY or implement additional projects to reduce overdraft in the Basin by 2030 to address the Basin’s historical overdraft.”].)
The UWMP must be revised to accurately reflect the impact of the PRP on the City’s groundwater supply over the years, and should further be revised to reflect that the PRP’s requirements have been met, and can continue to be met with the implementation of those demand reduction measures. Further, because the PRP does not act as a categorical restriction on the amount of water that may be pumped from the basin, the UWMP must be revised to also include the local sustainable yield that the City could utilize, i.e., the City’s own estimate of approximately 10,000 to 12,000 afy.

6. Patterson’s UWMP Conflicts With Other GSA’s UWMPs and the Adaptive Management Framework.

In contrast to Patterson’s UWMP, Los Banos’s draft UWMP does not limit or restrict it to any pumping reduction figure. Los Banos is subject to the same GSP as Patterson. It is part of the Zone 2 Pumping Reduction Plan. That plan calls for a pumping reduction from the lower aquifer of 3,139 afy. (Zone 2 Pumping Reduction Plan, p. 7.) The Zone 2 plan also notes that the representative wells in the Los Banos area show water level declines and that the Exchange Contractors established a “trigger water level” to address overdraft in the target area. This is similar to the MTs identified in the PRP, described in Section 2, supra.

Unlike Patterson’s UWMP, Los Banos’s UWMP shows its retail water supplies increasing from 7,997 afy (2025) to 11,604 afy (2050). (Los Banos UWMP, pp. 45-46.)13 The Los Banos UWMP states that Los Bason obtains its entire water supply from the underlying groundwater basin and plans to continue to rely solely on groundwater for its supply since it currently does not have surface water supplies or entitlements. (Los Banos UWMP, p. 45.) The Los Banos UWMP concludes:

While Los Banos is exceeding their safe yield, surrounding areas are making up the deficit through limited pumping and surface water importation. Specific mitigation goals for Los Banos have not yet been established. Hence a projection is not yet available regarding when the conversion to or supplementation with surface water may occur. Therefore, use of groundwater is assumed throughout the period of projections. (UWMP, p. 45.)
13 The Los Banos UWMP is incorporated herein by reference and can be found at:
https://losbanos.org/wp-content/uploads/2026/05/Los-Banos-2025-UWMP-Public-reviewDraft.2026.05.15.pdf.

Packet Pg. 948
Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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Patterson and Los Banos are in the same groundwater basin and covered by the same GSP and similar pumping reduction programs. Yet, Los Banos continues to approve housing projects without imposing conditions requiring purchase of surface water supplies or recharge of those supplies into the groundwater basin. (See footnote 10, supra.) Meanwhile, Patterson refuses to approve new housing projects, citing immediate pumping reduction “limits,” immediate recharge “obligations,” and immediate groundwater offset “requirements.” Patterson’s UWMP also conflicts with the Revised and Restated Memorandum of Understanding Among the Delta-Mendota Subbasin GSAs (“MOU”), including the Adaptive Management Framework for the Subbasin (“Framework”).
14 The MOU was adopted by Stanislaus
County on May 5, 2026. The UWMP does not even mention the updated MOU or the Framework.

The Framework acknowledges that SGMA implementation has a “long-term horizon” to achieve sustainability and requires an “iterative process” on the part of the GSAs to “review groundwater conditions at least annually and propose revisions to the underlying data, methodologies, assumptions, sustainable management criteria, projects, management actions, and other Subbasin-wide coordinated information as necessary to meet changing conditions.” (MOU, p. 17.)
The Framework applies to addressing MT downward trends or exceedances in the SGMA implementation period. (MOU, p. 17.) It calls for: (1) a review of Subbasin-wide data within 60 days after that data is due to be submitted, (2) consideration of, among others, changes in groundwater elevations, groundwater storage, subsidence, water quality and the status of MTs and interim milestones in the GSP, (3) holding of a hearing by the Authority’s Board of Directors to evaluate potential causes of any MT downward trend or exceedance, (4) presentation of a plan of action by the GSA to address how the GSA will mitigate any MT downward trend or exceedance and in what timeframe, recognizing that the GSA is “solely responsible for the management actions within its boundaries and the costs to remedy the cause of the MT exceedance if it is attributed to activities occurring within such GSA’s jurisdictional boundaries and/or that GSA is not operating within its Sustainable Yield,” (5) coordination with other GSAs to remedy the issue causing the MT downward trend or exceedance if it is determined to be caused by intra-basin impacts from another GSA, and (6) coordination with other subbasins to remedy the issue causing the MT downward trend of exceedance if it is determined to be caused by inter-basin impacts from a neighboring subbasin. (MOU, pp. 18-19.)
If the GSA is unable to mitigate or avoid future MT exceedances with its existing projects and management actions and within the timeframe presented, the GSA may seek assistance from the Authority. (MOU, p. 19.) The Authority may recommend policies or programs to the GSA 14 The MOU is incorporated herein by reference and can be found at:
https://www.stancounty.com/bos/agenda/2026/20260505/B04.pdf.

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Honorable Michael Clauzel, Mayor
and Members of the City Council
June 16, 2026

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that the GSA “could, in its discretion, adopt to remedy the existence of a MT exceedance and to avoid undesirable results.” (Id.) This may include setting triggers for GSA to implement management actions or work on alternative options. (Id.) Again the Framework reflects and matches a correct reading of the GSP and PRP as presented in Section 2, supra. In stark contrast, the City’s misrepresentation of the GSP and PRP (as reflected in the UWMP) do not correctly reflect or match the Framework.

7. Conclusion
In sum, the UWMP conflicts with the City’s own OYS—which found the City to have approximately 10,000-12,000 afy of sustainable supplies, the GSP—which provides for a series of actions to meet sustainability criteria by 2040 and does not artificially reset the City’s sustainable yield to 2,626 afy, and controlling State law—which does not authorize or justify the City’s actions.

As such, we urge the City Council to direct Staff to revise the draft UWMP to reflect the City’s OYS and to not adopt the UWMP in its current form.
********************
Thank you for your consideration of our client’s views on this important matter. Please do not hesitate to contact me with any questions regarding this correspondence.

Sincerely yours,

RUTAN & TUCKER, LLP
Matthew D. Francois
MDF
cc: Keith Schneider, Keystone Development, LLC ([email protected]) Fernando Ulloa, City Manager ([email protected])
Xavier Guluarte, Interim Public Works Director ([email protected]) Packet Pg. 950

EXHIBIT A
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TIMOTHY JONES*
MICHAEL S. HELSLEY
RILEY C. WALTER
PATRICK D. TOOLE
SCOTT D. LAIRD
JOHN P. KINSEY
KURT F. VOTE
ROBERT E. DONLAN
TROY T. EWELL
JAY A. CHRISTOFFERSON
AMANDA G. HEBESHA**
PETER M. JONES†
JEFFREY B. PAPE†
MARISA L. BALCH†
DEBORAH K. BOYETT
STEVEN K. VOTE
NICOLAS R. CARDELLA
GIULIO A. SANCHEZ
KATHLEEN D. DEVANEY
CRAIG A. CARNES, JR. †
* Also admitted in Washington
**
***
Also admitted in Idaho
Emeritus
† Of Counsel
†† Also admitted in Texas

WANGER JONES HELSLEY PC ATTORNEYS
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SHAWNDA M. GRADY†
ETHAN E. MORA†
BENJAMIN C. WEST
HUNTER C. CASTRO
STEPHANIE M. HOSMAN
IAN J. QUINN††
KEVIN W. BURSEY
RACHEL L. POMBO
DANIEL J. FREA
COLLEEN E. LITTLE
DANIKA E. JONES
JESSICA L. VIVED
HANNAH L. RAVIZZA
PAYTON D. DOLENAR
NINA M. ALVARADO
OLIVER W. WANGER***

LEGAL ADMINISTRATOR
LYNN M. HOFFMAN
April 19, 2026

VIA ELECTRONIC AND UNITED STATES MAIL
[email protected]
Matthew D. Francois
Rutan & Tucker
455 Market Street, Suite 1400
San Francisco, CA 94105
Re: Assessment of City of Patterson’s SGMA Basis for Denial of Keystone Ranch Vesting Tentative Map
Dear Mr. Francois:

This letter responds to your request for review of the City of Patterson’s (“City”) April 1, 2025 denial of the Vesting Tentative Map for the 719-unit Keystone Ranch housing project (“Project”), and specifically the City’s assertion that the 2014 Sustainable Groundwater Management Act (“SGMA”) and the Delta-Mendota Subbasin’s 2nd Revised Groundwater Sustainability Plan dated July 2024 (“2nd Revised GSP”) required the City to deny Approval of the Project. For the reasons set forth herein, the City’s assertion is incorrect and misrepresents the law—SGMA requires reasonable implementation actions towards long-term groundwater sustainability in the Delta Mendota Subbasin by 2040, and provides flexibility to local Groundwater Sustainability Agencies (“GSA”), such as the City, to achieve sustainability within such period of time. SGMA does not require, nor is it reasonable to expect, that sustainability can be achieved immediately, nor does it require mitigation associated with housing developments to be fully funded or that local jurisdictions fully implement mitigation and water supply augmentation measures before a City may approve new housing development projects.

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We understand that Keystone Ranch, LLC (“Keystone”) filed a petition for writ of mandate challenging the City’s denial of the Project on various grounds, including violation of State Housing Laws, and that petition currently is pending in Stanislaus Superior Court. (Keystone Ranch, LLC v. City of Patterson, Stanislaus County Superior Court Case No. CV-24-003269.) On September 22, 2025 the California Department of Housing and Community Development (“HCD”) sent a letter to the City asserting that the City’s denial of the Project’s Vesting Tentative Map was inconsistent with the Housing Accountability Act (“HAA”) and Housing Crisis Act (“HCA”), Government Code §§ 65589.5 and 66300 (“HCD Letter”). In the HCD Letter, HCD asked the City to: (1) provide the written findings required by the HAA and HCD and explain how those findings align with the commitments in the City’s draft housing element or (2) explain the City’s timeline for revisiting its denial of the Project and the conditions imposed on the Project.

We understand the City has taken neither such action to date.

In an October 22, 2025 letter to HCD, the City asserted, among other things, that it “does not have the ability to pump sufficient groundwater to serve [the] Keystone Ranch Development.” (“City Letter,” p. 1.) According to the City, the 2nd Revised GSP specifically prohibits the City from pumping groundwater to meet the demands of the Keystone Ranch development:

The 2nd Revised GSP . . . requires the City to reduce its existing groundwater pumping by . . . 460 acre-feet per year by 2030, thereby eliminating groundwater pumping as a source of water available to Keystone Ranch without additional planning. . . . [W]ith the adoption of the 2nd Revised GSP . . . groundwater pumping was no longer a source of water available to Keystone Ranch. Keystone Ranch did not provide an alternative source of water for their development project. This lack of water forms the basis of the City’s denial of the Application and is formally memorialized in the City Council’s findings in the rejection of the Application. (City Letter, p. 2.) The City also cites the Northern Delta-Mendota Regional Pumping Reduction Plan (Oct. 2024) (“PRP”) and asserts that the PRP requires the City to reduce groundwater pumping by 460 acre feet per year by 2030 before approving development with additional groundwater demands. (Id).

Neither SGMA, the 2nd Revised GSP, nor the PRP required or justified the City’s denial of the Keystone Ranch Project. In fact, there is no reason why the City cannot simultaneously comply with SGMA’s requirements and also comply with State housing laws in regard to the Project. After denying Keystone’s Project, the City subsequently approved four other development projects with equal or greater water demand. This inconsistent application confirms that SGMA compliance was not the true basis for the City’s action, but rather a pretext for the City’s denial of a housing development that cannot be sustained under State water laws or State housing laws.

SGMA
The 2nd Revised GSP requires 23 GSAs, including the City, to achieve sustainable groundwater management by 2040, but SGMA does not limit the discretion of local agency GSAs Packet Pg. 953

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to develop additional groundwater to meet existing and approved demands within its jurisdiction. (See, Wat. Code, § 10726.8, subd. (f) [“Nothing in this chapter or a [GSP] shall be interpreted as superseding the land use authority of cities and counties, including the city or county general plan, within the overlying basin.”]; subd. (a) [“This part is in addition to, and not a limitation on, the authority granted to a local agency under any other law.”].) To the contrary, SGMA provides a suite of management options for GSAs to manage groundwater supplies to avoid undesirable results in the Delta Mendota Subbasin, where such impacts are occurring, and at the same time allow the GSAs to develop and use groundwater from the Subbasin to serve existing and approved municipal water demands. (See, Wat. Code, § 10725, subd. (b) [“A [GSA] has and may use the powers in this chapter to provide the maximum degree of local control and flexibility consistent with the sustainability goals of this part.”], § 10720.1, subd. (b) [intent of SGMA is “[t]o enhance local management of groundwater consistent with rights to use . . . groundwater and [Article X, section 2 of the California Constitution], and to preserve the security of water rights in the state to the greatest extent possible consistent with the sustainable management of groundwater.”], § 10725.2, subd. (a) [GSAs “may perform any act necessary or proper to carry out the purposes of this part.”].) The fact that the City GSA has overdraft responsibilities under SGMA does not limit its authority and obligation to provide water supply to existing and approved customers within its service area. Rather, SGMA requires “the implementation of measures targeted to ensure that the applicable basin is operated within its sustainable yield [and avoids undesirable results].” (See, Wat. Code, § 10721, subds. (u), (v), (w).)1

NORTHERN DELTA-MENDOTA GSP AND PRP
The 2nd Revised GSP and PRP also does not support the City’s position. The GSP requires implementation of PRPs in each region of the basin to reduce pumping in areas where Minimum Thresholds (“MTs”) are exceeded and to avoid undesirable results where they occur. (See, GSP § 16.1.) Specifically, the GSP “requires the Basin GSAs, individually or as GSA Groups, to determine specific technical approaches and triggers that comply with the standards of the PRP . . . .” (GSP § 16.1.1.) Thus, “in the event of a Minimum Threshold (MT) exceedance, ‘the GSA shall present a plan of action to the Coordination Committee to address how the GSA will mitigate an exceedance and in what timeframe.’” (Id.) The GSP contemplates that PRPs will include a menu of options to achieve management thresholds, including an Overdraft Mitigation Plan (“OMP”), an MT Exceedance Plan, and other measures that, when collectively implemented, “. . . should ensure successful compliance with the GSP’s Sustainable Management Criteria (SMCs) and pumping within the Sustainable Yield . . ..” (Id.) The GSAs “may count pumping reductions implemented under the GWL-MT Avoidance Plan (Section 16.1.1.3), WQ-MT Exceedance Plan (Section 16.1.1.4), and Subsidence Avoidance Plan (Section 16.1.1.5) towards their minimum reductions [under the OMP].” (GSP § 16.1.1.2.). 2 1 Unless otherwise noted, emphasis in quotations is added and citations are omitted. 2 For example: “If the groundwater level at an RMW-WL exceeds the established trigger level, or is projected to exceed an MT, an investigation will be conducted to determine whether an area should be designated as an MT Packet Pg. 954

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Thus, while the OMP places a responsibility on the City GSA and other GSAs to meet sustainability thresholds, which may include managing existing and approved water demands and reducing pumping, that goal under the 2ndRevised GSP may be achieved through implementation of various plans and, under the PRP specifically, by targeting specific areas where MTs will be exceeded.
3 Indeed, the 2nd Revised GSP expressly acknowledges the lack of adaptiveness and flexibility of a management approach that relies solely on the OMP:

Although the implementation of the Overdraft Mitigation Plan . . . is expected to ensure long-term operation of the Basin within its Sustainable Yield, it lacks the adaptiveness to control adverse conditions due to localized impacts. Therefore the [MTs in the PRP] are proposed to facilitate local and/or short- to mid-term mitigation of adverse conditions and ensure consistent operation of the Basin within its defined SMCs, avoiding Undesirable Results.
(GSP § 16.1.7.1.)
The PRP establishes the OMP, which allocates pumping reduction responsibility for the northern region across the northern GSAs, including the City GSA. The City GSA’s pumping reduction target under the OMP is 92 AFY by the end of 2026 and 460 AFY by the end of 2030.

As noted, the OMP requires the City GSA to reduce pumping within its management area to ensure that groundwater elevations remain within the sustainable yield, but does not prohibit approval of additional water demand associated with approved development. Moreover, the OMP directs the City GSA to address undesirable results by reducing pumping in areas where MTs exceedances occur. Consistent with SGMA’s management framework, pumping reductions should be targeted to areas where MTs are exceeded, ensuring that pumping restrictions and other management actions are directly linked to achieving sustainability goals, as provided in the PRP:
[The OMP is one of the six PRP components.] For applicable PRP components, specific triggers and procedures are defined. These include an entry trigger to activate the PRP, a zone of impact (ZOI) to determine where the PRP will be applied, a cutback approach to provide quantitative estimates of pumping reductions, an exit trigger to conclude the cutback once objectives are met, and enforcement measures to ensure successful implementation. (PRP § 1.)
‘hotspot’ and will require an RMW-WL specific PRP. The PRPs will define the pumping reduction and/or other management actions to be implemented in the designated ‘hotspot’ during the year to correct a potential MT exceedance. The PRP will evaluate the groundwater level deficit, define lands to be restricted, and develop a pumping reduction on an acre-foot per acre basis by principal aquifer to be implemented and maintained up to the end of the water year or until monitoring indicates the groundwater level recovers to be above the established trigger level.” (GSP § 16.1.1.3) 3 According to the WY2024 Annual Report for the Delta-Mendota Subbasin, “groundwater elevations during WY2024 were largely above their respective minimum thresholds (MTs).” (WY2024 Annual Report, pp. ES-3; see also p. 2-5 [“Groundwater levels were largely near or above measurable objectives at a majority of the wells within the Subbasin during WY2023 and WY2024.”].)
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Pumping reductions under this [PRP to satisfy the OMP] may be adjusted and adapted based on model updates and . . . additional data and measurements. (PRP § 3.2.)
Further, with regard to groundwater level MTs, for example:
[M]ember GSAs are required to identify GWL-MT hotspots based on defined triggers by the end of February each year for identified groundwater level representative monitoring wells (RMW-WL) within each principal aquifer and implement targeted pumping cutbacks, on an acre foot per acre basis. These cutbacks will be applied at the rate and within an area determined by Zone of Impact (ZOI) and Cutback Approach (Section 4.3), accompanied by increased monitoring frequency, and adapted as required and justified under this plan. (PRP § 4.1)
The occurrence of any of the following conditions at an RMW-WL triggers a GWL-MT investigation [that] may lead to hotspot designation and require pumping reductions . . .
(PRP § 4.2.)
To achieve the desired groundwater level recovery, defined as the difference between the measured GWL and the trigger target, a uniform acre-foot per acre pumping limit will be identified within the ZOI. The cumulative impact of the defined cutback across the ZOI will be assessed to estimate the overall recovery at the RMW using the estimated sensitivities. The objective is to minimize the total volume of pumping reduction while achieving the necessary groundwater level increase (An example process is provided in Appendix A). The estimations of the ZOI and the cutback serve as starting points and will be adaptive. (PRP § 4.4)
If the targeted pumping reductions are not met, pumping is to be limited to the sustainable yield for the entire Basin and implemented through acre foot per acre allocations. (PRP § 7.3) According to the Delta-Mendota Subbasin Water Year 2024 Annual Report, Basin groundwater pumping in 2024 was 100,000 acre feet per year less than the subbasin’s total sustainable yield. 4 (WY 2024 Annual Report, p. 1-8). Further, we understand that the City is pumping approximately one-third of its sustainable yield. As such, the PRP triggers have not been met. 4 The vast majority of groundwater pumping in the Subbasin is due to agricultural uses and not domestic/urban/municipal uses, which comprise one percent of total water use. (WY2024 Annual Report, pp. 1-7, 1- 12 to 1-14.)
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As shown, the plain language of the 2nd Revised GSP and PRP does not support the City’s denial of the Project for not offsetting its groundwater use on a one-to-one basis. We understand that the Master Plan specifies that the Project and other development will implement, on a phased basis, infrastructure to support new development. Nothing in the 2nd Revised GSP amends or alters that plan. Instead, at most, it calls for a minimal reduction in pumping for Patterson of 460 afy by 2030, which we understand City officials have publicly stated could be met through conservation, use of recycled water, and related programs.

The City’s construction of the 2nd Revised GSP and PRP as imposing a moratorium on new development absent procurement of alternative water supplies is also at odds with its approval of four major development projects after denying the Keystone Ranch Project.5 Unlike Keystone,
none of these projects were conditioned on funding and constructing the City of Patterson Percolation Ponds for Stormwater Capture and Recharge Project (“Del Puerto Creek Project”) nor prohibited from proceeding with development until that project was completed. Indeed, the 2nd Revised GSP identifies the Del Puerto Creek Project as a City project to be implemented by 2040. (2nd Revised GSP, Chapter 15, Table PMA-1, p. 9; Table PMA-2, p. 5.) The City’s construction of the 2nd Revised GSP and PRP is also inconsistent with the actions of other similarly situated GSAs. For instance, we understand that in October 2025 the Stanislaus County Board of Supervisors approved a major groundwater supply infrastructure improvement project for the Crows Landing Industrial Business Park (“CLIBP”), which is covered by the same PRP as Patterson. The CLIBP consists of a 1,528-acre site planned for more than 14 million square feet of business and industrial space, a 370-acre public-use airport, and over 14,000 living-wage jobs. No conditions or limitations restricting development due to the GSP or PRP were imposed on the CLIBP, which is located approximately six miles south of Patterson.

The cities of Los Banos, Dos Palos, and Newman have likewise approved major housing development projects since approval of the 2nd Revised GSP without requirements that new development offset its groundwater usage with alternative water supply sources and not proceed with development until such sources are secured.
6 STATE HOUSING LAWS
5 (See Patterson Logistics Center-a 1.1 million square foot distribution center approved by the Planning Commission on June 12, 2025; Project Zach-a 3.2 million square foot warehouse and distribution center approved by the Planning Commission on June 26, 2025; West Commerce Park-a 1.1 million square foot warehouse and distribution center approved by the City Council on August 28, 2025; and Villages of Patterson-Olive Avenue-a residential subdivision of 162 lots approved by the City Council on August 19, 2025.) 6 (See, e.g., approvals by: (1) City of Los Banos City Council of San Luis Estates-a 96 unit residential development approved December 17, 2025, One Tree Cottages-a 58 unit residential development approved February 19, 2025, Snow Goose-a 25 townhome development approved November 20, 2024, Overland Trail Subdivision-a 50 unit residential development approved March 4, 2026, and Villages VI Subdivision-a 30 unit residential development approved February 4, 2026, (2) City of Dos Palos City Council of Rainbrook Run-a 102 unit residential development approved August 19, 2025, and (3) City of Newman City Council of Mattos Ranch-a mixed use commercial and residential project approved December 10, 2024.)
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As a general rule of statutory construction, when two statutes can be reconciled, “they must be construed in reference to each other, so as to harmonize the two in such a way that no part of either becomes surplusage.” (Friends of Riverside’s Hills v. City of Riverside (2008) 168 Cal.App.4th 743, 753 citing Royalty Carpet Mills, Inc. v. City of Riverside (2005) 125 Cal.App.4th 1110, 1118 and DeVita v. County of Napa (1995) 9 Cal.4th 763, 778-779.) The City’s construction of SGMA as prohibiting or imposing a moratorium on housing conflicts with State housing laws.

In contrast, construing SGMA as requiring phased implementation of actions and programs to sustainably maintain the groundwater basin (as detailed above) would comport with State housing laws.

The HAA restricts a city’s ability to deny housing development projects (that are consistent with objective planning, zoning, and subdivision standards), such as the Project. In order to lawfully deny (or reduce the density of) such projects, a city must fund that: (1) the housing development project would have a specific, adverse impact upon the public health or safety and (2) there is no feasible method to satisfactorily mitigate or avoid the adverse impact. (Gov. Code § 65589.5(j)(1).) As the HCD Letter accurately states, the City did not make these findings when denying Keystone’s Project.

Senate Bill 330 (Stats. of 2019) allows residential developers to vest the rules applicable to housing developments to those in effect when a preliminary application is submitted. (Gov.

Code §§ 65589.5(o), 65941.1.) Keystone submitted an initial SB 330 Preliminary Application for the Project on November 6, 2023 and a secondary SB 330 Preliminary Application on September 11, 2024 after the City refused to acknowledge the validity of the first submittal. The City did not adopt the 2nd Revised GSP until November 19, 2024, more than a year after Keystone submitted its initial SB 330 Preliminary Application. The 2nd Revised GSP was not in effect when Keystone submitted its SB 330 Preliminary Applications. Further, nothing in the two page staff report accompanying the Patterson City Council’s adoption of that plan said anything about pumping reductions, water shortages, or the need for new development to offset its water usage going forward.

The HCA prohibits a local agency from enacting “any development, standard, or condition that would impose a moratorium or similar restriction or limitation on housing development . . . other than to specifically protect against an imminent threat to the health and safety of persons residing in, or within the immediate vicinity of, the area subject to the moratorium . . ..” (Gov.

Code § 66300(a)(1)(5)(D).) The City proposed to include a condition on Keystone’s Project that it could not be issued a building permit until the “Del Puerto Creek Project shall be sufficiently completed for the delivery of water for recharge at the Del Puerto Creek Project location.” (AR 7124.) The City estimated the cost of the Del Puerto Creek Project to be roughly $20 million (in 2024 dollars) and that it would take at least five years to complete construction of it. As the HCD Letter correctly notes, the City did not undertake the analysis required by the HCA to support this restriction or limitation on housing development.

In addition, state law requires that local agencies include in their Housing Elements an inventory of land suitable and available to meet the agency’s Regional Housing Needs Allocation Packet Pg. 958

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(“RHNA”). (Gov. Code §§ 65583(a)(3), 65580(f), 65583.2(a).) In order to be deemed “suitable,” the land must have, among others, availability and access to water, sewer, and other utilities. (Gov.

Code § 65583.2(b)(5); see also Gov. Code § 65583(a)(3) [requiring an analysis of zoning and public facilities and services to housing inventory sites].) The City’s RHNA for its Sixth Cycle Housing Element (2023-2031) is 3,716 units.7
The Keystone Ranch Project is identified in the
Revised Draft Housing Element (“RDHE”) as one of the key housing opportunity sites needed to meet the City’s RHNA obligations. (RHDE, pp. 4-9, 4-14, A-3, A-67.) The Revised Draft Housing Element also contains programs whereby the City commits to facilitating the phasing of infrastructure to enable timely residential development to meet the City’s RHNA, with check-in points to obtain 3,503 residential building permits by June 2027. (RDHE, pp. 3-17 to 3-21.) The City’s denial of Keystone’s Project cannot be squared with its Revised Draft Housing Element.

CONCLUSION
The City’s reliance on SGMA, the GSP, and the PRP as justification for denying the Keystone Ranch Project is not supported by applicable law or the factual record. SGMA provides GSAs with an array of management options to achieve groundwater sustainability within the Subbasin, and it requires GSAs to focus their management actions on measures that will reduce and eliminate undesirable results where they exist. The City has not availed itself of the full range of options that SGMA authorizes, and it has not made the findings required for the demand management options it has implemented. Rather, the City has unofficially imposed a building moratorium on the Keystone Project alone, under the guise of implementing SGMA, while it has proceeded with approving other major development projects that cumulatively have an equal or higher water demand. The City’s failure to impose any meaningful groundwater management measures on existing customers and approving other new development without preconditions reveals that compliance with SGMA’s groundwater sustainability requirements and the PRP are but a pretext for the City’s denial of the Keystone Project.

Very truly yours,
Robert E. Donlan
CC: David Lanferman
Debbie Gavaghan
Pat Gavaghan
Thomas Cleverdon
Cassie Gilson
RED/dlp
7 On March 24, 2026, HCD issued a Notice of Violation to the City for being more than two years delinquent in adopting its 2023-2031 Housing Element. The City was one of only 15 jurisdictions in the State to receive such a letter.

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EXHIBIT B
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City of
Patterson
Water
Shortage
Contingency
Plan 2025
June 2026
woodardcurran.com
95 Third Street | 2
nd Floor
San Francisco, California 94103
800.426.4262
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City of Patterson (0013240.00) i Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

TABLE OF CONTENTS

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

2. WATER SUPPLY RELIABILITY ANALYSIS.......................................................................................2-2

2.1 Water Service Reliability Findings.............................................................................................................2-2

2.2 Seismic Risk Assessment and Mitigation Plan.................................................................................. 2-10

3. ANNUAL WATER SUPPLY AND DEMAND ASSESSMENT PROCEDURES ................................. 3-11

4. WATER SHORTAGE STAGES........................................................................................................ 4-13

5. SHORTAGE RESPONSE ACTIONS................................................................................................ 5-16

5.1 Supply Augmentation Actions ................................................................................................................ 5-16

5.2 Demand Reduction Actions ..................................................................................................................... 5-17

5.3 Operational Changes.................................................................................................................................. 5-19

5.4 Additional Mandatory Restrictions ....................................................................................................... 5-20

6. COMMUNICATION PROTOCOLS ................................................................................................ 6-21

7. COMPLIANCE AND ENFORCEMENT........................................................................................... 7-22

8. LEGAL AUTHORITIES ................................................................................................................... 8-23

9. FINANCIAL CONSEQUENCES OF WSCP ..................................................................................... 9-24

10. MONITORING AND REPORTING .............................................................................................. 10-25

11. WSCP REFINEMENT PROCEDURE............................................................................................. 11-26

12. SPECIAL WATER FEATURE DISTINCTION ................................................................................ 12-27

13. PLAN ADOPTION, SUBMITTAL, AND AVAILABILITY.............................................................. 13-28 Packet Pg. 965
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TABLES
Table 2-1. Normal Year Supply and Demand Comparison (DWR Table 7-2) Table 2-2. Normal Year Supply and Demand Comparison (Potable Only) Table 2-3. Normal Year Supply and Demand Comparison (Non-Potable Only) Table 2-4. Single Dry Year Supply and Demand Comparison (DWR Table 7-3) Table 2-5. Single Dry Year Supply and Demand Comparison (Potable Only) Table 2-6. Single Dry Year Supply and Demand Comparison (Non-Potable Only) Table 2-8. Multiple Dry Years Supply and Demand Comparison (DWR Table 7-4) Table 2-9. Multiple Dry Years Supply and Demand Comparison (Potable Only) Table 2-10. Multiple Dry Years Supply and Demand Comparison (Non-Potable Only) Table 2-10. Drought Risk Assessment (DWR Table 7-5)
Table 4-1: Water Shortage Contingency Plan Levels
Table 4-2: Cross-Reference for Standard vs. Supplier Shortage Levels (DWR Table 8-1) Table 5-1: Supply Augmentation and Other Actions (DWR Table 8-2) Table 5-2: Demand Reduction Actions (DWR Table 8-3)
Table 6-1: Communication Protocol for Each Water Shortage Level Table 7-1: WSCP Penalties and Charges

APPENDICES
Appendix A: Public Notices and Resolutions
Appendix B: Emergency Response Plan (ERP)
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LIST OF ACRONYMS AND ABBREVIATIONS
Acronym Definition
AF Acre-Feet
AFY Acre-Feet per Year
AMI Advanced Metering Infrastructure
CIMIS
California Irrigation Management Information
System
City City of Patterson
CVP Central Valley Project
CWC California Water Code
DOF California Department of Finance
DRA Drought Risk Assessment
DWR California Department of Water Resources
ERP Emergency Response Plan
gpcd Gallons per Capita per Day
GSP Groundwater Sustainability Plan
MCL Maximum Contaminant Level
PRP Pumping Reduction Plan
Subbasin Delta-Mendota Subbasin
SWRCB State Water Resources Control Board
THM Total Trihalomethanes
UWMP Urban Water Management Plan
UWUO Urban Water Use Objective
WSCP Water Shortage Contingency Plan
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1. INTRODUCTION
The City of Patterson (City) Water Shortage Contingency Plan (WSCP) is a detailed operational plan that documents how the City will respond to a variety of water shortage scenarios. The WSCP establishes protocols for triggering City-wide water supply shortage levels, implementing corresponding water shortage response actions to respond to actual supply conditions, and ensures the strategic management of a short- or long-term water shortage event.

A water shortage may occur due to a variety of potential scenarios, such as drought, climate change, regulatory constraints, natural or human caused disasters, and catastrophic events which may occur at any time. The WSCP is the City’s operating manual that allows the City Council, staff, and the public to identify and efficiently implement pre-determined steps to manage a water shortage.

To match the Urban Water Management Plan (UWMP), the City reports water volumes in units of acre-feet (AF) and acre-feet per year (AFY) in the WSCP.

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2. WATER SUPPLY RELIABILITY ANALYSIS
California Water Code (CWC) Section 10632(a)(1) requires an analysis of water supply reliability per CWC Section 10635. The City relies exclusively on groundwater to meet customer needs and has historically met customer demands through times of drought. Conditions could arise such as catastrophic events, prolonged periods of drought, unforeseen impacts to the groundwater supply, etc. that could require the activation of the WSCP.

2.1 Water Service Reliability Findings
The City maintains seven (7) potable well facilities and associated water storage tanks, and three (3) nonpotable irrigation-only well facilities to meet the maximum day demand and fire protection requirements of its water system with the largest well source offline, in accordance with State of California Code of Regulations, Title 22 California Waterworks Standards. All water is pumped from the Delta-Mendota Subbasin.

The rest of this subsection summarizes at a high level the assumptions and results of the water service reliability analysis conducted as part of Chapter 7 of the 2025 UWMP.

Assumptions by water supply source:
• Groundwater, Lower Aquifer: 2,626 AFY for 2030 and beyond in all year types, based on pumping limitations set by the Northern Delta‑Mendota Region Pumping Reduction Plan (PRP) • Groundwater, Upper Aquifer: Approximately 2,000 AFY for potable uses, and 677 AFY for nonpotable uses, in all year types. • Del Puerto Creek Recharge and Recovery project:
o Normal Year:
▪ Stormwater: 750 AFY
▪ Surface water: 800 AFY
o Single dry year:
▪ Stormwater: 491 AF – Based on precipitation data collected at the Patterson CIMIS Station for Water Years 2000-2017, precipitation in dry and critically dry years (San Joaquin water year index) is 65% of average year precipitation of 12.2 inches per year. Thus, the 750 AF of average year supply available from stormwater is assumed to be 750 * 65% = 491 AF.
▪ Surface water: 800 AF; single-dry years are assumed to result in no reduction of available supply from Del Puerto Canyon Reservoir.
o Five consecutive dry years:

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▪ Stormwater: 491 AF – same assumption as a single-dry year; during the 2012-2016 multi-year drought, precipitation was variable but was similar to the overall average of dry and critically dry years.
▪ Surface water: the first year of a 5 consecutive dry year cycle is assumed to provide the full assumption of 800 AF of surface water supply. In subsequent years, the City assumes water will be available from Del Puerto Canyon Reservoir, but at a reduced rate similar to reductions in allocations made for South of Delta urban contractors from the Central Valley Project during the 2012-2016 drought (70% of supply allocation in 2013 as year 2, 50% in 2014 as year 3, 25% in 2015 as year 4, and 55% in 2016 as year 5).
• Surface water expansion project
o Normal Year: Up to 6,000 AFY
o Single dry year: No reduction
o Five consecutive dry years: same percent reductions as was described for surface water in the Del Puerto Creek Recharge and Recovery project.
• As-needed purchase of additional surface water to supplemental non-potable uses:
o All year types: as-needed basis to meet non-potable demands, as described in UWMP The following DWR reporting tables depict the City’s water reliability assessment showing water demands and water supply availability for various water supply scenarios.

Table 2-1 depicts normal year supply and demand conditions through 2050 indicating the City has adequate supplies to meet future water needs during normal year conditions. Table 2-2 shows the same comparison for potable only, while Table 2-3 shows only non-potable supplies and demands.

TABLE 2-1. NORMAL YEAR SUPPLY AND DEMAND COMPARISON (DWR TABLE 7-2) 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals 4,909 5,364 5,937 11,391 11,410
Use totals 4,804 5,364 5,937 6,516 6,648
Surplus/(shortfall) 105 0 0 4,875 4,762
Note – Required DWR Table 7-2 combines both supply and demands for potable and non-potable supplies which must be considered separately for the City of Patterson. See the following two tables for a breakdown of Potable and Non-Potable scenarios.

TABLE 2-2. NORMAL YEAR SUPPLY AND DEMAND COMPARISON (POTABLE ONLY) 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals 4,176 4,471 4,883 10,176 10,176
Use totals 4,071 4,471 4,883 5,301 5,414
Surplus/(shortfall) 105 0 0 4,875 4,762
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TABLE 2-3. NORMAL YEAR SUPPLY AND DEMAND COMPARISON (NON-POTABLE ONLY) 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals 733 893 1,054 1,215 1,234
Use totals 733 893 1,054 1,215 1,234
Surplus/(shortfall) 0 0 0 0 0
Table 2-4 depicts single dry year supply and demand conditions through 2050. Table 2-5 shows the same table for potable supplies and demands only, with Table 2-6 only including non-potable supplies and demands.

TABLE 2-4. SINGLE DRY YEAR SUPPLY AND DEMAND COMPARISON (DWR TABLE 7-3) 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals 4,647 5,102 5,675 11,129 11,148
Use totals 4,804 5,364 5,937 6,516 6,648
Surplus/(shortfall) (158) (263) (263) 4,613 4,500
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit 158 263 263
WSCP - use reduction savings benefit
Revised Surplus/(shortfall) 0 0 0
Note – Required DWR Table 7-3 combines both supply and demands for potable and non-potable supplies which must be considered separately for the City of Patterson. See the following two tables for a breakdown of Potable and Non-Potable scenarios.

TABLE 2-5. SINGLE DRY YEAR SUPPLY AND DEMAND COMPARISON (POTABLE ONLY) 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals 3,914 4,209 4,621 9,914 9,914
Use totals 4,071 4,471 4,883 5,301 5,414
Surplus/(shortfall) (158) (263) (263) 4,613 4,500
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit 158 263 263
WSCP - use reduction savings benefit
Revised Surplus/(shortfall) 0 0 0
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TABLE 2-6. SINGLE DRY YEAR SUPPLY AND DEMAND COMPARISON (NON-POTABLE ONLY) 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals 733 893 1,054 1,215 1,234
Use totals 733 893 1,054 1,215 1,234
Surplus/(shortfall) 0 0 0 0 0
Table 2-7 depicts supply and demand conditions through 2050 for a multiple dry year scenario (five consecutive dry years), similar to the 2012-2016 drought cycle. Table 2-8 shows the same table with potable supplies and demands only, while Table 2-9 shows only non-potable supplies and demands.

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TABLE 2-7. MULTIPLE DRY YEARS SUPPLY AND DEMAND COMPARISON (DWR TABLE 7-4) 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
First year
Supply totals 4,647 5,102 5,675 9,029 11,148
Use totals 4,804 5,364 5,937 6,516 6,648
Surplus/(shortfall) (158) (263) (263) 2,513 4,500
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit 158 263 263
WSCP - use reduction savings benefit
Revised Surplus/(shortfall) 0 0 0 4,613 4,500
Second
year
Supply totals 4,407 4,862 5,435 9,089 9,108
Use totals 4,804 5,364 5,937 6,516 6,648
Surplus/(shortfall) (398) (503) (503) 2,573 2,460
OPTIONAL WSCP Actions
WSCP - supply augmentation benefit 0 55 14
WSCP - use reduction savings benefit 407 447 488
Revised Surplus/(shortfall) 10 0 0 2,573 2,460
Third
year
Supply totals 4,247 4,702 5,275 7,729 7,748
Use totals 4,804 5,364 5,937 6,516 6,648
Surplus/(shortfall) (558) (663) (663) 1,213 1,100
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit 150 215 174
WSCP - use reduction savings benefit 407 447 488
Revised Surplus/(shortfall) 0 0 0 1,213 1,100
Fourth
year
Supply totals 4,047 4,502 5,075 6,029 6,048
Use totals 4,804 5,364 5,937 6,516 6,648
Surplus/(shortfall) (758) (863) (863) (488) (601)
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit 814 894 977 1,060 1,083 Revised Surplus/(shortfall) 57 32 114 573 482
Fifth year
Supply totals 4,287 4,742 5,315 8,069 10,788
Use totals 4,804 5,364 5,937 6,516 6,648
Surplus/(shortfall) (518) (623) (623) 1,553 4,140
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit 611 671 732
Revised Surplus/(shortfall) 93 48 110 1,553 4,140
Note – Required DWR Table 7-4 combines both supply and demands for potable and non-potable supplies which must be considered separately for the City of Patterson. See the following two tables for a breakdown of Potable and Non-Potable scenarios.

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TABLE 2-8. MULTIPLE DRY YEARS SUPPLY AND DEMAND COMPARISON (POTABLE ONLY) 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
First
year
Supply totals 3,914 4,209 4,621 9,914 9,914
Use totals 4,071 4,471 4,883 5,301 5,414
Surplus/(shortfall) (158) (263) (263) 4,613 4,500
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit 158 263 263
WSCP - use reduction savings benefit
Revised Surplus/(shortfall) 0 0 0
Second
year
Supply totals 3,674 3,969 4,381 7,874 7,874
Use totals 4,071 4,471 4,883 5,301 5,414
Surplus/(shortfall) (398) (503) (503) 2,573 2,460
OPTIONAL WSCP Actions
WSCP - supply augmentation benefit 0 55 14
WSCP - use reduction savings benefit 407 447 488
Revised Surplus/(shortfall) 10 0 0
Third
year
Supply totals 3,514 3,809 4,221 6,514 6,514
Use totals 4,071 4,471 4,883 5,301 5,414
Surplus/(shortfall) (558) (663) (663) 1,213 1,100
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit 150 215 174
WSCP - use reduction savings benefit 407 447 488
Revised Surplus/(shortfall) 0 0 0
Fourth
year
Supply totals 3,314 3,609 4,021 4,814 4,814
Use totals 4,071 4,471 4,883 5,301 5,414
Surplus/(shortfall) (758) (863) (863) (488) (601)
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit 814 894 977 1,060 1,083 Revised Surplus/(shortfall) 57 32 114 573 482
Fifth
year
Supply totals 3,554 3,849 4,261 6,854 9,554
Use totals 4,071 4,471 4,883 5,301 5,414
Surplus/(shortfall) (518) (623) (623) 1,553 4,140
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit 611 671 732
Revised Surplus/(shortfall) 93 48 110
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TABLE 2-9. MULTIPLE DRY YEARS SUPPLY AND DEMAND COMPARISON (NON-POTABLE ONLY) 2030
(AF)
2035
(AF)
2040
(AF)
2045
(AF)
2050
(AF)
First
year
Supply totals 733 893 1,054 1,215 1,234
Use totals 733 893 1,054 1,215 1,234
Surplus/(shortfall) 0 0 0 0 0
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Second
year
Supply totals 733 893 1,054 1,215 1,234
Use totals 733 893 1,054 1,215 1,234
Surplus/(shortfall) 0 0 0 0 0
OPTIONAL WSCP Actions
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Third
year
Supply totals 733 893 1,054 1,215 1,234
Use totals 733 893 1,054 1,215 1,234
Surplus/(shortfall) 0 0 0 0 0
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Fourth
year
Supply totals 733 893 1,054 1,215 1,234
Use totals 733 893 1,054 1,215 1,234
Surplus/(shortfall) 0 0 0 0 0
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
Fifth
year
Supply totals 733 893 1,054 1,215 1,234
Use totals 733 893 1,054 1,215 1,234
Surplus/(shortfall) 0 0 0 0 0
OPTIONAL Planned WSCP Actions
WSCP - supply augmentation benefit
WSCP - use reduction savings benefit
Revised Surplus/(shortfall)
The Drought Risk Assessment (DRA) is an evaluation of local water supply availability, assuming the next five years (2026-2030) are hydrologically equivalent to the driest five consecutive years on record. The assumptions are summarized below, with more detail in Section 7 of the 2025 UWMP:

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• Unconstrained demands for 2026-2029 were linearly interpolated between 2025 actuals and 2030 projected demands for the “existing” service area without Zacharias Baldwin development.

Demands for the Zacharias Baldwin development are assumed to first come online in 2029, before reaching the 2030 projected value, meaning 0 AFY of demands 2026-2028. • Groundwater supply, Lower Aquifer: Pumping reductions scale from 92 AFY in 2025 to 460 AFY in 2030. The model-estimated baseline pumping from the Lower Aquifer from Water Years 2019-2023 is 3,086 AFY. Thus the 2025 available Lower Aquifer supply is assumed to be 2,994 AF and 2030 available supply is 2,626 AF, with 2026-2029 linearly interpolated between those values. • Groundwater supply, Upper Aquifer: Shown to be equal to non-potable demands, as the City expects enough non-potable supplies to be available to meet these demands in any year type. The City also anticipates transitioning some Upper Aquifer supplies from serving non-potable demands to serving potable demands (after treatment is added) sometime over the next 5-10 years.

Table 2-10 contains the results of the drought risk assessment.

TABLE 2-10. DROUGHT RISK ASSESSMENT (DWR TABLE 7-5)
2026 Total Potable Non-Potable
Total Water Use (AF) 4,215 3,678 537
Total Supplies (AF) 3,457 2,920 537
Surplus/Shortfall w/o WSCP Action (757) (757) 0
OPTIONAL Planned WSCP Actions (use reduction and supply augmentation) WSCP - supply augmentation benefit (AF)
WSCP - use reduction savings benefit (AF) 757 757
Revised Surplus/(shortfall) 0 0
2027 Total Potable Non-Potable
Total Water Use (AF) 4,284 3,698 586
Total Supplies (AF) 4,284 3,698 586
Surplus/Shortfall w/o WSCP Action 0 0 0
2028 Total Potable Non-Potable
Total Water Use (AF) 4,352 3,717 635
Total Supplies (AF) 4,352 3,717 635
Surplus/Shortfall w/o WSCP Action 0 0 0
2029 Total Potable Non-Potable
Total Water Use (AF) 4,578 3,894 684
Total Supplies (AF) 4,579 3,895 684
Surplus/Shortfall w/o WSCP Action 0 0 0
2030 Total Potable Non-Potable
Total Water Use (AF) 4,804 4,071 733
Total Supplies (AF) 4,804 4,071 733
Surplus/Shortfall w/o WSCP Action 0 0 0
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2.2 Seismic Risk Assessment and Mitigation Plan
The CWC requires the City’s WSCP to include a seismic risk assessment and mitigation plan to assess the vulnerability of each water facility. Per CWC Section 10632.5 (c), this requirement is met by the Stanislaus 2022 Multi-Jurisdictional County Hazard Mitigation Plan which includes hazard vulnerability assessments and mitigation plans (including for earthquakes). This plan is available to the public through the Stanislaus County Office of Emergency Services website (oes.stancounty.gov). There are several major faults in the region that could generate a seismic event that could impact City water facilities including the Great Valley Thrust Fault System, Ortigalita Fault Zone, and the San Joaquin Fault. The City closely monitors its water facilities and is prepared to rehabilitate infrastructure should an earthquake hazard impact its water system.

The City’s Emergency Response Plan (ERP) describes the City’s plan for responding to a variety of other catastrophic water shortage conditions, such as the impacts of a seismic event. A copy of the ERP can be found in Appendix B.

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3. ANNUAL WATER SUPPLY AND DEMAND ASSESSMENT PROCEDURES CWC Section 10632 (a)(2) requires written procedures to be developed to conduct an annual water supply and demand assessment (annual assessment) to determine the water system’s reliability, assuming the upcoming year is a dry year. The annual assessment and accompanying shortage report must be completed and submitted to the California Department of Water Resources (DWR) by July 1 of each year. For these annual assessments and shortage reports, the “year” refers to the 12-month period beginning July 1 and ending the following June 30 per DWR guidelines.

The documented steps to complete the annual assessment are described below, as well as the decisionmaking process for declaring a shortage.

Available Water Supply
As previously described, the City relies exclusively on groundwater supplies. Available water supplies for the City shall be quantified each year by summing the capacity of each operational groundwater well, typically assuming that one well is offline. The resulting well capacity will be compared to the available groundwater supply that can be pumped under any limitations imposed by the Pumping Reduction Plan that the City participates in as a management action from the Delta-Mendota Subbasin Groundwater Sustainability Plan (GSP). Typically, the lower of the two values is used as an estimated available supply for the coming year.

Unconstrained Customer Demand
Water use for the previous year of available data at the time the analysis is conducted shall be quantified by summing the billed water usage for all customers by user class for the previous year. Customer water demands for the City shall be projected for the upcoming year based on the previous year’s water usage and anticipated new customer connections and per capita target assumptions. If a water shortage was active during the previous year, demands will be increased by the estimated percent reduction requested or otherwise imposed during the active water shortage period.

The first step to calculate the anticipated additional new demand is to calculate the future population changes. To calculate future population, the number of anticipated new customer connections shall be multiplied by the number of persons per household as indicated on updated Department of Finance (DOF) data tables shown on the DOF website for the City. That number shall then be added to the current population to obtain the future population.

𝐹𝑢𝑡𝑢𝑟𝑒 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 = 𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 + (𝑁𝑜. 𝑜𝑓 𝑁𝑒𝑤 𝐶𝑜𝑛𝑛𝑒𝑐𝑡𝑖𝑜𝑛𝑠 × 𝑃𝑒𝑟𝑠𝑜𝑛𝑠 𝑝𝑒𝑟 𝐻𝑜𝑢𝑠𝑒ℎ𝑜𝑙𝑑) To calculate anticipated demands for the upcoming year, each meter usage per customer class shall be multiplied by the future population and then divided by the current population.

𝐴𝑛𝑡𝑖𝑐𝑖𝑝𝑎𝑡𝑒𝑑 𝐷𝑒𝑚𝑎𝑛𝑑 =
𝑀𝑒𝑡𝑒𝑟 𝑈𝑠𝑎𝑔𝑒 × 𝐹𝑢𝑡𝑢𝑟𝑒 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛
Evaluation Criteria
If the available water supply is greater than the anticipated customer demand for the upcoming year, then the City would not need to take any further action. If the anticipated customer demands for the upcoming Packet Pg. 978
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year are greater than the available water supplies, the City will initiate appropriate water shortage response actions as detailed in this WSCP.

Infrastructure Considerations
If infrastructure projects are anticipated for the upcoming year that could impact water supply production (e.g. repairs and/or replacement of existing wells, development of new groundwater well, etc.), these water supply impacts shall be evaluated for the timeframe (i.e. months) when the infrastructure projects will impact the available water system capacity. Thus, the available water supply shall be increased or reduced accordingly for each month based on expected months of well non-availability and/or when new or replacements supplies are developed and brought online providing additional system capacity.

Decision-Making Process
If a shortage is predicted for the coming year, the shortage report will be presented to the City Council following the completion of the annual assessment. The City Council shall review and approve the findings of the annual assessment and if necessary, trigger implementation of any water shortage response actions resulting from the annual assessment findings through a resolution.

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4. WATER SHORTAGE STAGES
CWC Section 10632 (a)(3)(A) requires standard water shortage levels including greater than a 50-percent reduction in water supply conditions. The City follows the standard six water shortage levels, also known as stages, suggested by DWR’s 2025 Urban Water Management Plan Guidebook. The City will implement these water shortage levels in response to corresponding water supply shortages to comply with CWC requirements. The stages will be implemented during water supply shortages, due to City water system constraints, or due to outside factors (e.g. State water use cutbacks or regional drought conditions that may not be directly influencing the City’s water supplies). The determination and declaration of a water supply shortage stage will be made by the City of Patterson City Council.

Stage 1
This level would be initiated during a mild water shortage (up to 10%) and is part of an ongoing public information campaign encouraging voluntary water conservation. The City could achieve up to a 10% reduction voluntarily or could issue a resolution triggering Stage 1 voluntary water use reductions up to 10%. There are no mandatory measures implemented during a Stage 1 response. Although Stage 1 is very achievable, customers would be reminded of regional dry year concerns and any short interruptions in water service when the City may have a redundant back-up well offline for repairs, which makes the overall supply system more vulnerable to shortages.

Stage 2
This level would be initiated during a moderate water shortage (11-20%) and would be addressed through enhanced voluntary measures and public outreach with voluntary enforcement of the water waste ordinance. Failure of one groundwater supply well could cause a moderate reduction in water supply, resulting in implementation of Stage 2 measures. Stage 2 would also be implemented during an on-going regional drought condition where water conservation is voluntary with little to no actual impact on the City’s groundwater supply capacity. During Stage 2 conditions, the City Council could declare certain water use prohibitions in accordance with the City’s water waste ordinance.

Stage 3
This level would be initiated during a more severe water shortage (21 to 30%), which could be caused by State-mandated water use reductions or a catastrophic failure of up to two City groundwater supply wells.

During a Stage 3 condition, the City Council would implement a combination of voluntary and mandatory measures as needed to meet the specific water shortage cutback target. The City Manager would have the authority to implement City Council directed water shortage response measures including the implementation of additional prohibitions and consumption reduction methods that could include cutbacks in irrigation water use by all customers, enhanced leak repair by utilities and customers, City establishment of water shortage pricing surcharges, and other consumption reduction methods as needed to effectively reduce water demands to match available supplies.

Stage 4
This level would be initiated during a critical water shortage (31 to 40%), which could be caused by a catastrophic failure of up to three groundwater supply wells. All actions taken in the prior stages would be intensified and production would be monitored daily for compliance with necessary water use reductions.

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City of Patterson (0013240.00) 4-14 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026
Customers would be under strict enforcement of no waste policies and water rationing would be considered.

The City may declare a water shortage emergency to immediately repair and bring well capacity back online in a timely manner.

Stage 5
This level would be initiated during a critical water shortage (41-50%), which could be caused by a natural disaster, prolonged severe drought event, or catastrophic failure of water system facilities that greatly reduces water supply capacity by more than 40% from normal operation capacities. Severe limitations would be placed on irrigation use by all customers, leaks would be required to be repaired within five days, and all non-essential City operations (e.g. flushing) would be curtailed until further notice.

Stage 6
This level would be initiated during a catastrophic water shortage (>50%), which could be caused by a natural disaster or catastrophic failure requiring severe and immediate cutbacks in customer water demands. Rationing and mandatory restrictions would be enhanced as needed to effectively reduce water demands to match available supplies. Indoor use may be capped on an account-level basis at the State mandated indoor residential urban water use objective on a gallons per capita per day (gpcd) basis.

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City of Patterson (0013240.00) 4-15 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026
Table 4-1 summarizes the City’s six (6) water shortage levels included in a compliant WSCP. As indicated in the following Table 4-2, these are the standard six levels of water shortage.

TABLE 4-1: WATER SHORTAGE CONTINGENCY PLAN LEVELS
Shortage
Level
Percent Shortage
Range
Numerical value
as a percent
Water Shortage Condition
(Narrative description)
1 Up to 10%
Mild Water Shortage - drought or loss of
redundant wellsupply.
2 Up to 20%
Moderate Water Shortage - drought or temporary loss
of one (1) well.
3 Up to 30%
Severe Water Shortage - drought, State cutbacks, or
permanent loss of one (1) well.
4 Up to 40%
Critical Water Shortage - extended drought, State
cutbacks, loss of two (2) wells.
5 Up to 50%
Critical Water Shortage - extended drought, State
cutbacks, loss of three (3) wells.
6 >50%
Catastrophic Water Shortage - natural disaster, major
system failures, energy supply disruptions.

NOTES: Cutbacksin water use will be based on triggered shortage level and percent reduction target based on normal year per capita water use levels.

TABLE 4-2: CROSS-REFERENCE FOR STANDARD VS. SUPPLIER SHORTAGE LEVELS (DWR TABLE 8-1) Check the box if the Supplier uses the Standard six
levels of water shortage.

Proceed to the next table.

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City of Patterson (0013240.00) 5-16 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

5. SHORTAGE RESPONSE ACTIONS
In the case that a shortage is declared, the City would implement appropriate response actions to address anticipated supply and demand gaps. These response actions address the water shortage on multiple fronts and include supply augmentation, demand reduction, and operational changes. As water shortage severity increases, corresponding response measures become more mandatory and severe to ensure that percent shortage cutback targets are met during a given water shortage event. For example, the City would migrate from voluntary water use reduction methods utilized in stages 1 and 2, to more mandatory actions during a stages 3 and 4. Response actions can be added or modified as needed to achieve percent reduction targets with least impact on customers and the economy. The following sections summarize the City’s planned response actions.

5.1 Supply Augmentation Actions
The City has very few supply augmentation options especially for potable water supplies. Developing additional non-potable wells supplies or adding new recycled water options would take years to develop and would not be available during the short-term shortage condition at hand. The City might consider emergency exchanges, transfers, or purchases on an interim basis of water supplied from neighboring water agencies as feasible. These would be very expensive to the City and would likely be non-potable emergency supplies with limited uses in the City service area. The City could also attempt to increase pumping capacity from operational wells. Table 5-1 indicates some of the options available to the City to stretch existing supplies or augment under emergency conditions.

TABLE 5-1: SUPPLY AUGMENTATION AND OTHER ACTIONS (DWR TABLE 8-2) Yes Is the Supplier completing this table using the standard six levels? (yes/no) Shortage
Level
Supply Augmentation
Methods and Other Actions
by Water Supplier
How much is this going to
reduce the shortage gap? Additional Explanation or
Reference
Volume or (OPTIONAL)
Percentage
Shortage Gap
Reduction
Value
3 and 4
Implement or Modify
Drought Rate Structure or
Surcharge
Percentage up to 5%
(or 200 AF)
Cover additional costs associated
with water shortage response
actions
5 and 6 Other Actions Volume 912 AF Increase pumping from existing potable wells (12 hrs/day)
5 and 6 Other Actions Volume 2,129 AF Increase pumping from existing non-potable wells (24 hrs/day)
5 and 6 Exchanges Percentage up to 10%
(or 400 AF)
Bring in temporary non-potable
supplies
NOTES: The City has very few supply augmentation measures other than to increase pumping capacity from existing wells and attempt to secure short-term supplies from neighboring agencies, which would be very expensive to the City and likely only benefit non-potable uses.

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City of Patterson (0013240.00) 5-17 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

5.2 Demand Reduction Actions
Because supply augmentation opportunities are extremely limited, the City’s water shortage response actions focus heavily on demand reduction. Table 5-2 lists the potential demand reduction measures the City would implement as additional WSCP stages are triggered by shortage conditions. As previously stated, these reduction actions may be modified as needed to achieve the necessary demand reduction targets while minimizing impact to customers.

TABLE 5-2: DEMAND REDUCTION ACTIONS (DWR TABLE 8-3)
Shortage
Level
Demand Reduction
Actions
How much is this going
to reduce the shortage
gap?
Additional Explanation or
Reference
(OPTIONAL)
Penalty,
Charge, or
Other
Enforcement?
Volume or
Percentage
Drop down
Shortage
Gap
Reduction
Value
(May be a
range)
1 to 2 Other Percentage 0 - 20% Voluntary Restrictions - No Waste No
1 to 2
Expand Public
Information
Campaign
Percentage 0 - 20%
General increase in public
outreach measures
including social media,
apps, and other means
No
1 to 2 Improve Customer
Billing Percentage up to 5%
Provide more real-time
water use data as
available through AMI
projects
No
1 to 2 Offer Water Use
Surveys Percentage up to 5% Especially to large water users No
1 to 3 Other Percentage 0 - 30% Voluntary Water Use
Reductions No
1 to 2
Provide Rebates on
Plumbing Fixtures
and Devices
Percentage up to 5% Enhance plumbing fixture
rebates No
1 to 3 Other Percentage 10 - 30% Expedite conversion of water efficient fixtures No
1 to 3
Landscape - Limit
landscape
irrigation to
specific days
Percentage 0 - 20% Limit irrigation to 3
watering days/week Yes
1 to 4 Landscape - Limit
landscape Percentage 0 - 40% Limit irrigation to 2 watering days/week Yes Packet Pg. 984
City of Patterson (0013240.00) 5-18 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026
Shortage
Level
Demand Reduction
Actions
How much is this going
to reduce the shortage
gap?
Additional Explanation or
Reference
(OPTIONAL)
Penalty,
Charge, or
Other
Enforcement?
Volume or
Percentage
Drop down
Shortage
Gap
Reduction
Value
(May be a
range)
irrigation to
specific days
1 to 6
Other - Customers
must repair leaks,
breaks, and
malfunctions in a
timely manner
Percentage 10-50%+ Repair within 5 days of
detection No
2 to 6
Landscape -
Prohibit certain
types of landscape
irrigation
Percentage 20 - 50%+ Reduce parks/open space
irrigation No
3 and 4
Provide Rebates
for Landscape
Irrigation Efficiency
Percentage up to 5%
Provide or enhance
landscape rebates (e.g.
sprinkler rebates)
No
3 and 4 Decrease Line
Flushing Percentage up to 5%
Reducing line flushing
while still avoiding THM
MCL violations
No
3 and 4
Implement or
Modify Drought
Rate Structure or
Surcharge
Percentage up to 5%
Cover additional costs
associated with water
shortage response
activities, and encourage
additional conservation
Yes
3 to 6
Expand Public
Information
Campaign
Percentage 30 - 50%+ General and specific
public outreach measures No
3 to 6 Reduce System
Water Loss Percentage 20 - 50%+ Expedite larger utility leak repairs No 3 to 6 Increase Water
Waste Patrols Percentage 20 - 50%+
Mandatory restrictions -
no waste enforced via
patrols, tickets, fines, etc.

Yes
3 to 6
Implement or
Modify Drought
Rate Structure or
Surcharge
Percentage 20 - 50%+ Apply water shortage
pricing for surcharge Yes
3 to 6 Other Percentage 20 - 50%+ Apply penalties for
excessive water use Yes
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City of Patterson (0013240.00) 5-19 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026
Shortage
Level
Demand Reduction
Actions
How much is this going
to reduce the shortage
gap?
Additional Explanation or
Reference
(OPTIONAL)
Penalty,
Charge, or
Other
Enforcement?
Volume or
Percentage
Drop down
Shortage
Gap
Reduction
Value
(May be a
range)
4 to 6 Other Percentage 30 - 50%+ Restrict water use for only priority uses Yes
5 and 6 Other Percentage Up to 1%
Increased security or
monitoring by City staff
of hydrants to avoid
unauthorized
consumption
No
5 and 6
Moratorium or Net
Zero Demand
Increase on New
Connections
Percentage Up to
10%
Discuss phasing
permitted development Yes
5 and 6
Landscape -
Prohibit certain
types of landscape
irrigation
Percentage Up to
10%
Significant irrigation
prohibitions Yes
5 to 6
Landscape -
Prohibit certain
types of landscape
irrigation
Percentage 40 - 50%+ No lawn watering Yes
5 to 6 Other Percentage 40 - 50%+ Apply flow restrictions to customers
Yes
5 to 6 Other Percentage 40 - 50%+
Mandatory water
rationing, per capita
allotment
Yes
Yes Is the Supplier completing this table using the standard six levels? (yes/no)

5.3 Operational Changes
During a triggered water supply shortage condition the City can implement operational changes such as reducing water system flushing and increasing hydrant security. Operational changes are included in Table 5-2 as appropriate.

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City of Patterson (0013240.00) 5-20 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

5.4 Additional Mandatory Restrictions
The City could implement additional mandatory restrictions against specific water use practices that may be considered excessive during given water shortage conditions. If drought or water shortages warrant mandatory restrictions (considered for Stage 3), the City could implement further restrictions if warranted based on Stage 3 or Stage 4 conditions. Table 5-2 identifies mandatory restrictions that would be enforced during a water shortage.

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City of Patterson (0013240.00) 6-21 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

6. COMMUNICATION PROTOCOLS
The CWC Section 10632 (a)(5)(A) requires the City to notify all customers and interested parties of any anticipated water shortages as result of the annual water supply and demand assessment process. Per, the CWC Section 10632 (a)(5)(B), the City will also notify all customers and interested parties if any shortage response actions are triggered pursuant to the annual water supply and demand assessment results. In the event of an anticipated water shortage, the City will inform customers through newsletters and messages on the City website, water bill inserts, direct mail (e.g. post cards), newspapers, press releases, advertising, social media (NextDoor App), mobile electronic street signs, community workshops and meetings, and other communications as needed to meet water shortage reduction targets.

Communication protocols are summarized below in Table 6-1.

TABLE 6-1: COMMUNICATION PROTOCOL FOR EACH WATER SHORTAGE LEVEL Standard Shortage
Level
Standard Shortage
Levels
Typical Response
Action Type
Percent
Shortage Range
Communication Method
1 Voluntary Up to 10% Website
2 Enhanced Voluntary Up to 20% Stage 1 methods, plus:

Bill Insert, Newsletter
3 Voluntary/Mandatory Up to 30%
Stage 1 & 2 methods, plus:

Direct Mail, Newspaper, Press
Release, Advertising, Social Media,
Mobile Electronic Street Sign
4 Voluntary/Mandatory Up to 40%
Stage 1-3 methods, plus:

Community Workshop and
Meetings
5 Restrictions/Allocations Up to 50%
Stage 1-4 methods, plus:

Targeted Restriction and Allocation
Communications
6 Restrictions/Allocations > 50%
Stage 1-5 methods, plus:

Enhanced Targeted Restriction and
Allocation Communications
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City of Patterson (0013240.00) 7-22 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

7. COMPLIANCE AND ENFORCEMENT
CWC Section 10632 (a)(6) requires an urban water supplier to penalize or charge for excessive use, where applicable. In accordance with the City Municipal Code (through adoption of the 2025 WSCP), when a water shortage emergency is declared, the City Manager may issue a Notice of Violation to any customer that fails to comply with the conditions of the ordinance. After one notice has been issued, further violations shall be punishable by a fine of: $25 for a first violation; $50 for a second violation; and $100 for a third violation; and thereafter the City may exercise the option of terminating water service for flagrant water waste compliance and enforcement situations.

Furthermore, each day upon which any condition of the ordinance is violated constitutes a separate violation. The City will ensure compliance and enforce provisions through water use field patrols, calls received at City offices, and/or communications received through social media supported by the City. The City will maintain records of all enforcement actions. The City Municipal Code will maintain updated policies and procedures related to implementation of the City’s updated WSCP.

During severe and critical water shortages (Stages 3-6), there may be additional penalties or charges applied for excessive water use. During these triggered water shortage conditions, the City Manager may take further actions if violations continue after the initial written warning, such as installing a flow-restricting device on the service line or termination of service for repeated violations of unauthorized water use. Table 7-1 summarizes when penalties and charges may take effect.

TABLE 7-1: WSCP PENALTIES AND CHARGES
Penalty or Charge Stage When Penalty or Charge Takes Effect Penalty for excess use 3-6
Charge for excess use 3-6
Flow Restriction 5-6
Termination of Service 5-6
In accordance with the City’s Municipal Code (Section 13.24.240), violations or fines may be appealed for reconsideration. Appeals for reconsideration shall be processed as indicated in the City Municipal Code provisions.

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City of Patterson (0013240.00) 8-23 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

8. LEGAL AUTHORITIES
The City is a general law city with authorities to govern City business and services and enter into agreements or arrangements beneficial to the City in accordance with State laws and regulations. Per the City Municipal Code, the City has the authority to implement the water response actions presented herein and as necessary to meet the public health and safety needs of the community. The City has water code provisions in place to address water supply shortage and water waste conditions.

The City shall approve a DWR compliant WSCP by July 21, 2026 and may declare a water shortage emergency as required depending on the severity of the water shortage level/stage in accordance with CWC Chapter 3, Sections 350 through 359. This includes provisions related to penalties and charges associated with WSCP implementation actions.

The City shall coordinate with Stanislaus County for the possible proclamation of a local water supply emergency per California Government Code, California Emergency Services Act, Article 2, Section 8558.

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City of Patterson (0013240.00) 9-24 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

9. FINANCIAL CONSEQUENCES OF WSCP
CWC Section 10632 (a)(8) requires a description of the impacts of consumption reduction on the revenues and expenditures of the urban water supplier. The City has established an accounting system for tracking expenses and revenue shortfalls associated with voluntary and mandatory water use reductions implemented through WSCP water shortage response actions. The City maintains reserve funds that can be used to offset expenditure impacts during times of emergency. Further, the City would implement a water surcharge upon triggering of a Stage 3 (or higher) WSCP declaration to recover unmitigated revenue shortfalls resulting from the costs of additional water shortage response actions. The water surcharge would only be in effect during the declared water shortage condition. Any water-related surcharges would be approved by the City Council, validating the need for the surcharges and identifying appropriate costs to be covered through any approved surcharges to support WSCP implementation.

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City of Patterson (0013240.00) 10-25 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

10. MONITORING AND REPORTING
Per CWC Section 10632 (a)(9), the City will monitor and report on the implementation of its WSCP. Monthly metered water production and consumption data will be collected, tracked, and analyzed to monitor compliance and meet SWRCB water conservation reporting requirements. This water use reporting process will assist the State to determine compliance with per capita water use targets, established end use targets, and future cutback policy response during prolonged drought conditions.

As of June 2024, the City completed deployment of an Advanced Metering Infrastructure (AMI) system which collects hourly read data and provides real-time leak detection information for customers. Compared to pre-AMI meter reading, the additional AMI meter data provides the City with a real-time tracking tool to monitor customer water use and reductions levels during a triggered water shortage condition. The City has also made real-time water use information available to customers through an online EyeOnWater portal.

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City of Patterson (0013240.00) 11-26 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

11. WSCP REFINEMENT PROCEDURE
Per CWC Section 10632 (a) (10), the City may choose to refine the WSCP based on monitoring and reporting of data collected. The City’s WSCP can be refined or updated at any time, independent of when UWMPs are updated every five years. Based on analysis of the data collected, the City may choose to modify or add consumption reduction methods to more accurately meet water level targets. Any updates to the WSCP will be approved by the City Council as needed to maintain an effective water shortage response plan for the community.

Any WSCP updates will allow for interested party review and be publicly noticed before any City Council action is considered at a planned City Council meeting. The WSCP documents and any updated information will be available on the City’s website.

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City of Patterson (0013240.00) 12-27 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

12. SPECIAL WATER FEATURE DISTINCTION
The City does not have any special water features of distinction that are artificially supplied with water and would be involved in a WSCP response effort.

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City of Patterson (0013240.00) 13-28 Woodard & Curran, Inc. 2025 Water Shortage Contingency Plan June 2026

13. PLAN ADOPTION, SUBMITTAL, AND AVAILABILITY
The City conducted a public hearing to review its 2025 UWMP and WSCP at the June 16, 2026 City Council Meeting. Public notices were posted at least 7 and 14 days prior in the Patterson irrigator newspaper. The City’s 2025 UWMP and WSCP documents were available for review prior to the City Council meeting on the City’s website. The final 2025 UWMP and WSCP were adopted at the City Council Meeting on July 21, 2026.

The resolution and related public noticing can be found in Appendix A.

The City’s adopted 2025 UWMP and WSCP were submitted to DWR through DWR’s online data portal and provided to the California State Library. The City’s 2025 UWMP and WSCP were also made available to interested parties involved in the plan development process including the County and agencies listed in Chapter 10 of the 2025 UWMP. The City’s adopted Final 2025 UWMP and WSCP are available for viewing or download from the City’s website.

Per the CWC, the following steps shall be performed prior to adoption of the WSCP. • Prior to adoption, the City will issue a notification of a public hearing to customers, the county, and other interested parties.
• The City will publish a public notice in a local newspaper for two consecutive weeks prior to the public hearing.
• The City shall hold a public hearing to obtain public input. • Following the public hearing or at a subsequent City Council meeting, the City Council shall formally adopt the WSCP.
• Per CWC Section 10632 (a)(c), the City will make the WSCP available on the City’s website, https://www.pattersonca.gov/669/Urban-Water-Management-Plan, within 30 days of adoption by the City Council.

The City may choose to amend its 2025 WSCP at any time on an as needed basis which will follow the steps listed above independent of future City UWMP updates.

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City of Patterson (0013240.00) Woodard & Curran, Inc.
2025 Water Shortage Contingency Plan June 2026
APPENDIX A: PUBLIC NOTICES AND RESOLUTIONS
Packet Pg. 996

DEPARTMENT OF PUBLIC WORKS
e
s b.

April 8, 2026DATE:

SUBJECT:

Sincerely,
Department of Public Works
7laza
Cc: Aracely Alegre, City Clerk
TO:

FROM:

Existing state law requires each urban water supplier to prepare and adopt an urban water management plan at least once every five years. The City of Patterson (City) is currently preparing an update to its 2020 Urban Water Management Plan (UWMP) and Water Shortage Contingency Plan (WSCP). Together, the UWMP and WSCP document the City’s plans to ensure adequate water supplies to meet existing and future demands for water under a range of water supply conditions, including water shortages.

Maria Encinas, CFM
Water Resources Program Manager
Notice of Plan Preparation for 2025 Urban Water Management Plan & 2025 Water Shortage Contingency Plan Update
As part of the UWMP process, the City is required to notify those agencies which the City receives water from, sells water to, or the County in which water is delivered (California Water Code § 10621 (b)).

Additionally, the City is notifying those agencies listed in the Northern Delta-Mendota Region Management Committee. If you receive this letter, the City is either required to notify you or has chosen to do so voluntarily.

We anticipate having draft documents available for public review beginning May 13, 2026, with a public hearing anticipated for June 16, 2026 at a regularly scheduled City Council meeting. Once available, materials available for review will be posted to the City’s website at www.pattersonca.gov.

The final documents will be submitted to the California Department of Water Resources by July 1, 2026.

If you have any questions, please contact me at (209) 895-8061 or [email protected].

All Interested Parties
Maria Encinas, Water Resources Program Manager
William Barrera
Deputy Director - Operations & Maintenance
Sonia Delgado, QSP, CESSWI
Deputy Director - Regulatory Compliance & Administrative Services City Hall: 1 Plaza, Patterson, CA 95363 • Phone: (209) 895-8060 Corporation Yard: 16215 Baldwin Road, Patterson, CA 95363 • Phone: (209) 895-8160 Water Quality Control Facility: 14901 Poplar Avenue, Patterson, CA 95363 • Phone: (209) 895-8150 Main Email Address: [email protected]
Xavier Guluarte
Interim Director of Public Works
Packet Pg. 997

LEGAL NOTICE

NOTICE OF PUBLIC HEARING

NOTICE IS HEREBY GIVEN THAT THE CITY OF PATTERSON CITY
COUNCIL will hold a Public Hearing in the City Council Chamber, 1 Plaza, Patterson, CA, on Tuesday, June 16, 2026 at 7:00 p.m., to consider comments on the city’s 2025 Urban Water Management Plan (UWMP) and Water Shortage Contingency Plan (WSCP). The purpose of the public hearing is to provide an opportunity for interested persons to be heard regarding the city’s 2025 UWMP, which describes the city’s water supply reliability, demand management measures and long-term water resource planning. The City anticipates that the documents will be considered for adoption at the following City Council Meeting on Tuesday, July 7, 2026.

NOTICE IS ALSO HEREBY GIVEN that these documents will be available for public review beginning on or about May 15-18, 2026 or by calling Public Works at (209) 895-8060. Documents will be located at City Hall, 1 Plaza, Patterson, CA 95363 or online at www.pattersonca.gov. All interested parties are invited to review the documents prior to the closing of the Public Hearing scheduled Tuesday, June 16, 2025 meeting at 7:00 p.m.

ALL INTERESTED PARTIES are invited to attend the hearing and express their opinions. At the above noted time and place, testimony from interested persons will be heard by the City Council and duly considered prior to taking action on the variance. Any material submitted to the City Council for consideration (photographs, petitions, letters, etc.) will be retained by the City and cannot be returned. Comments may also be submitted to [email protected] anytime before the close of Public Hearing noted above.

FURTHER INFORMATION may be obtained by contacting the City Clerk’s Office of the Patterson, City Hall by email at [email protected] or by calling (209) 895-8014.

BY ORDER OF THE CITY COUNCIL OF THE CITY OF PATTERSON.

Date(s) Advertised: May 21, 2026
Aracely Alegre, City Clerk
City of Patterson
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City of Patterson (0013240.00) Woodard & Curran, Inc.
2025 Water Shortage Contingency Plan June 2026
APPENDIX B: EMERGENCY RESPONSE PLAN (ERP)
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Packet Pg. 1155
Packet Pg. 1156
Packet Pg. 1157
Packet Pg. 1158
Packet Pg. 1159
Packet Pg. 1160
Packet Pg. 1161
Packet Pg. 1162
Packet Pg. 1163
Packet Pg. 1164
Packet Pg. 1165
Packet Pg. 1166
Packet Pg. 1167
Packet Pg. 1168
Packet Pg. 1169
Packet Pg. 1170
Packet Pg. 1171
Packet Pg. 1172
Packet Pg. 1173
Packet Pg. 1174
Packet Pg. 1175
Packet Pg. 1176
Packet Pg. 1177
Packet Pg. 1178
Packet Pg. 1179
Packet Pg. 1180
Packet Pg. 1181
Packet Pg. 1182
Packet Pg. 1183
Packet Pg. 1184
Packet Pg. 1185
Packet Pg. 1186
Packet Pg. 1187
Packet Pg. 1188
Packet Pg. 1189
Packet Pg. 1190
Packet Pg. 1191
Packet Pg. 1192
Packet Pg. 1193
Packet Pg. 1194
Packet Pg. 1195
Packet Pg. 1196
Packet Pg. 1197
Packet Pg. 1198
Packet Pg. 1199
Packet Pg. 1200
Packet Pg. 1201
Packet Pg. 1202
Packet Pg. 1203
Packet Pg. 1204
Packet Pg. 1205
Packet Pg. 1206
Packet Pg. 1207
Packet Pg. 1208
Packet Pg. 1209
Packet Pg. 1210
Packet Pg. 1211
Packet Pg. 1212
Packet Pg. 1213
Packet Pg. 1214
Packet Pg. 1215
Packet Pg. 1216
Packet Pg. 1217
Packet Pg. 1218
Packet Pg. 1219
Packet Pg. 1220
Packet Pg. 1221
Packet Pg. 1222
Packet Pg. 1223
Packet Pg. 1224
Packet Pg. 1225
Packet Pg. 1226
Packet Pg. 1227
Packet Pg. 1228
Packet Pg. 1229
Packet Pg. 1230
Packet Pg. 1231
Packet Pg. 1232
Packet Pg. 1233
Packet Pg. 1234
Packet Pg. 1235
Packet Pg. 1236
Packet Pg. 1237
Packet Pg. 1238
Packet Pg. 1239
Packet Pg. 1240
Packet Pg. 1241
Packet Pg. 1242