2025 Urban Water Management Plan

Section 2 REDUCED RELIANCE ANALYSIS Zone 7 Water Agency Reduce Reliance on the Delta 2 DRAFT | April 2026 The analysis and documentation provided below include all of the elements described in WR P1(c)(1) that need to be included in a water supplier’s UWMP to support a certification of consistency for a future covered action. Including this document as an appendix in the 2015 and subsequent Urban Water Management Plans fulfills the requirements of WR P1 subsection (c)(1) Paragraph A. 2 REDUCED RELIANCE ANALYSIS The data used in this analysis represent the regional efforts of Zone 7 to serve its customers in the Tri- Valley, including municipal and industrial (M&I) retailers (California Water Service, Dublin San Ramon Services District, City of Livermore, and City of Pleasanton), M&I direct retail customers, and untreated water customers. The analysis was coordinated with Zone 7’s retailers as part of the UWMP coordination process as described in the 2025 UWMP. In accordance with UMWP requirements, Zone 7’s retailers report their demand and supply data for their respective service areas in their respective UWMPs. This appendix reports demands on Zone 7 and supplies served by Zone 7. The retailers report their other sources of supplies used to supplement Zone 7 supplies in their UWMPs as applicable (e.g., recycled water, groundwater pumped by the retailer). Zone 7 provided the info presented here to the retailers so they can appropriately represent the nature of their wholesale supplies from Zone 7, and those supplies’ contributions to reduced Delta reliance. The methodology used to determine Zone 7’s reduced Delta reliance and improved regional self-reliance is consistent with the approach detailed in Appendix C of Department of Water Resources’ (DWR) Urban Water Management Plan Guidebook 2025 (Guidebook Appendix C) issued in January 2026, including the use of narrative justifications for the accounting of supplies and the documentation of specific data sources. General assumptions include: • All data were obtained from the current 2025 UWMP or previously adopted UWMPs and represent average or normal water year conditions. • All analyses were conducted at the wholesale level, focusing on Zone 7’s demands and sources of supplies served to the Tri-Valley. • As described in Chapter 6 of the 2025 UWMP, Zone 7 is currently pursuing a number of water supply and storage alternatives to bolster water system reliability while reducing reliance on the Delta. The future projects described in Chapter 6 and the demand management measures described in Chapter 9 fulfill the requirements of WR P1 subsection (c)(1) Paragraph B. For the purposes of the 2025 UWMP, a representative future water supply portfolio was selected; that portfolio is reflected in this analysis. Tables 1 through 4 present the analysis of Zone 7’s reduced Delta reliance using DWR’s spreadsheet tool and fulfill the requirements of WR P1 subsection (c)(1) Paragraph C. Descriptions of the various inputs of the analysis are provided below: • Baseline (2010) and 2015-2050 Conditions – The analysis uses a normal water year representation of 2010 as the baseline, which is consistent with the approach described in DWR’s Guidebook. Data for the 2010 baseline were taken from the 2010 UWMP (Table 9-11). To evaluate conditions relative to the baseline, actual conditions for 2015, 2020, and 2025 from Table 4-1 of the corresponding UWMPs are presented. Normal year projections for 2030 through 2050 from the 2025 UWMP are then subsequently used. In its 2025 UWMP, Zone 7 does not include operational storage—groundwater recharge and State Water Project (SWP) carryover—in its current or projected demands. To maintain consistency with baseline and 2015 conditions, operational storage has been added to actual (2025) and projected (2030-2050) demands presented in Zone 7’s 2025 UWMP. • Service Area Water Demands with Water Use Efficiency Accounted For – These values reflect Zone 7’s actual and projected water use, including water placed in storage as applicable.