RES 2026043 - Laserfiche WebLink

Section 6 2025 Urban Water Management Plan Water Supply Characterization City of Pleasanton Public Draft | May 2026 6-4 EKI Environment & Water, Inc. From 2020 to 2025, Table A allocations ranged from 5% to 100%, resulting in substantial annual variability in Zone 7’s SWP supply. DWR has projected decreasing reliability of Table A supplies. In the Draft 2025 DCR, DWR projects long-term average Table A allocations to decrease from 54% under existing conditions to 48% under future conditions in 2043 for the 50% level of concern scenario. Since the future conditions scenario incorporates impacts from climate change and sea level rise, it is more conservative than the existing conditions scenario. Zone 7’s 2025 UWMP assumes SWP supply availability for 2030 through 2050 considering Table A allocations under the 50% level of concern in the Draft 2025 DCR. This enables Zone 7 to consider the impacts of future climate change throughout the planning horizon. Zone 7 plans to further assess water supply reliability using the 75% and 95% level of concern in future studies to examine various scenarios. As a SWC, Zone 7 has the option to store unused Table A water from one year to the next in the SWP’s San Luis Reservoir when storage capacity is available. This “carryover” water is also called Article 12e or 56c water, in reference to the relevant contract terms. While Article 12e water must be taken by March 31 of the following year, Article 56c water may remain as carryover if San Luis Reservoir storage is available. Zone 7’s UWMP analysis assumes an average of 10,000 AFY of carryover. Article 21 Water (Interruptible or Surplus Water) Article 21 of the SWP contract allows SWCs to take deliveries above the approved and scheduled Table A amounts for the current year when surplus SWP water is available. Article 21 water is only available for delivery on a short-term basis as determined by DWR when water is still available after operational requirements for SWP water deliveries, water quality, and Delta requirements are met. Article 21 deliveries cannot be stored in the SWP system. This water becomes available during short periods in the wet season when storms bring excess water that DWR cannot store in San Luis Reservoir. When Article 21 water becomes available, SWCs can request delivery, and the available water is distributed generally in proportion to the Table A contract amounts of SWCs requesting delivery. Delivery of Article 21 water requires the ability to store the water in a non-SWP facility during very wet conditions and/or the ability to use the water directly without impacting scheduled Table A deliveries to Zone 7 (i.e., Article 21 delivery cannot be used to substitute scheduled Table A deliveries). As described in the Draft 2025 DCR, Article 21 water deliveries are highly variable year-to-year, and also by month. Historically, these conditions have been difficult to meet for Zone 7 and have resulted in infrequent and low yields. On average, Article 21 water is available for Zone 7 about once every six years. Zone 7 last received Article 21 water in 2023, when it took 2,360 AF. Having access to additional storage in the future would increase Zone 7’s access to Article 21 water. 6.1.2.1.3 Yuba Accord In 2008, Zone 7 executed a contract with DWR to purchase additional water under the Lower Yuba River Accord (Yuba Accord). The original contract expired in 2025, and several amendments have been executed over the years, including a recent 2026 extension through 2056. Four different types (“Components”) of Yuba Accord water are made available as a water purchase or transfer. Zone 7 has the option to purchase Components 1, 2, and 3 water during drought conditions and Component 4 water when the Yuba County Water Agency has determined that it has water supply available to sell. Water is primarily available during dry years under the Yuba Accord, and the amount is highly variable. Zone 7 has purchased Yuba Accord water in 12 of the last 18 years, purchasing as little as 41 AF in 2025 and as much as 3,159 AF in 2013. For planning purposes, Zone 7 currently does not assume any water