CITY COUNCIL REGULA MEETING AGENDA PACKET _Revised_ 6-2-26

Page 2 of 3 adoption of the Draft 2025 UWMP and WSCP, included as Attachment 1. DISCUSSION The City’s water supply reliability is closely tied to Zone 7’s water supply reliability policy. Since 2023, Zone 7 has provided 100 percent of the City’s potable water supply and serves as the Tri-Valley groundwater manager. As a result, Zone 7’s seasonal and climatic supply constraints directly affect the City’s supply reliability and vulnerability to shortages. The water quantity available to Zone 7 from its different supply sources varies annually depending on hydrologic conditions. Accordingly, as part of Zone 7’s 2025 UWMP preparation, Zone 7 reviewed historical data and developed projected yields for each water supply source under three conditions: (1) normal water year, (2) single-dry year, and (3) a consecutive five- year drought. This information, in turn, informed the City’s water supply reliability assessment. The key outcome of the Draft 2025 UWMP and WSCP is that Zone 7 is expected to have adequate supply reliability to meet the City’s current and projected demands through 2045 under the majority of analyzed scenarios. The only scenario showing a small shortfall for Pleasanton (10 percent) is a five-year drought beginning in 2045, specifically in the fifth consecutive year of drought. This shortfall is considered manageable through conservation measures consistent with the WSCP. To strengthen delivery reliability, Zone 7’s current portfolio includes future water supply projects such as groundwater banking, water transfers, Site Reservoir, and the Chain of Lakes Project, as well as exploratory planning for potable reuse and desalination. Each water shortage event is unique and requires a situational assessment, and the WSCP details the City’s strategic approach. Accordingly, during potential future water shortage events, staff will assess supply in close coordination with Zone 7, as outlined in the WSCP, and, when applicable, bring forward recommendations to the City Council based on the assessment findings. Update Following Public Draft Release Following the release of the Public Draft 2025 UWMP and WSCP, the State Division of Drinking Water (DDW) adjusted the City’s water loss standard from the original version shown in Table 4-3 from a “Real Water Loss Standard” of 18.8 gallons per service connection per day (gpscpd) shown, to 28.5 gpscpd. The final 2025 UWMP and WSCP will reflect the updated value in Table 4-3 and include minor associated language adjustments to Section 4.4 to reflect this updated information. This DDW-approved adjustment to the City’s original real water loss standard followed an economic water loss model analysis provided by City staff, demonstrating that a higher standard was justified. The DDW-approved adjusted value will improve future compliance with the water loss standard and the Urban Water Use Objective requirement under the Making Water Conservation a Way of Life regulations. EQUITY AND SUSTAINABILITY Adoption of the draft 2025 UWMP and WSCP supports long-term water supply reliability and is consistent with Strategy WR-1 of the City’s Climate Action Plan 2.0. Page 381 of 617