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Section 6 2025 Urban Water Management Plan Water Supply Characterization City of Pleasanton Public Draft | May 2026 6-2 EKI Environment & Water, Inc. • Incoming water supplies – Including supplies available through contracts and water rights and typically consist of annually allocated imported surface water supply and local surface water runoff. • Accumulated or “banked” water supplies – Including supplies derived from previous years that are held in local and non-local storage locations. To optimize use of its local resources, Zone 7 practices conjunctive use of the Basin, as detailed in Section 6.2.3. Zone 7 also stores local runoff from the Arroyo Valle watershed in the local reservoir (Lake Del Valle), which is owned and operated by DWR as part of the SWP. Groundwater banking provides Zone 7 with additional flexibility in managing annual fluctuations in supplies. Zone 7 currently holds long-term water storage (“banking”) agreements with two agencies in Kern County: Semitropic Water Storage District and Cawelo Water District. Additionally, Zone 7 is in the process of obtaining a new water storage agreement with another agency. To mitigate the risk associated with significant reliance on imported water supply, Zone 7 continues to develop local sources of water to diversify its water supply portfolio. Zone 7 periodically conducts Water Supply Evaluation (WSE) Updates to assess future water supply conditions in the Tri-Valley to support long-term water supply reliability. In May 2023, Zone 7 completed its 2022 WSE Update to capture the latest assumptions for Zone 7’s system, supply, and demands. The 2022 WSE Update also evaluated various potential future water supplies, discussed in Section 6.8. 6.1.2.1 Imported Water from the State Water Project Zone 7’s primary source is imported water from the SWP, which is owned and operated by DWR. On an average annual basis, SWP supply accounts for about 90%8 of Zone 7’s portfolio (Zone 7, 2026). SWP water supply originates in the Feather River watershed, where water is captured in Lake Oroville, released into the Feather River to flow through the Delta, then conveyed through the South Bay Aqueduct (SBA). From the SBA, the supply may be stored in Lake Del Valle (along with local runoff) or conveyed to Zone 7 and/or two other water agencies (Valley Water and Alameda County Water District [ACWD]). Much of the SWP water continues to flow to southern California via the California Aqueduct. SWP water is used by Zone 7 to meet potable demands from municipal and industrial (M&I) customers and untreated water demands from agricultural customers. When possible, Zone 7 also uses SWP to artificially recharge the Basin (Section 6.2.3.3) and to fill non-local groundwater storage (i.e., groundwater banks in Kern County; Section 6.1.2.4). The following sections describe Zone 7’s contract with DWR for SWP water and the types of water Zone 7 receives under this contract. 6.1.2.1.1 Contract with DWR DWR provides water from the SWP to 29 water suppliers (State Water Contractors [SWC]) in exchange for contractor payment of all costs associated with providing that supply. DWR established substantially uniform long-term water supply contracts with each SWC in the 1960s, including Zone 7’s SWP contract initially executed in 1961. That contract has been subsequently amended 28 times and currently terminates on December 31, 2085. Details regarding Zone 7’s contract with DWR are provided in Zone 7’s 2025 UWMP. 8 This includes direct SWP deliveries, SWP carryover, and groundwater that originated from the SWP that was stored for later use.