Item 21 - Public Hearing - Resolutions Approving the 2025 Urban Water Management Plan and the 2025 Water Shortage Contingency Plan

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2025 URBAN WATER MANAGEMENT PLAN MAY 2026/FINAL DRAFT/CAROLLO (CPTP). The CPTP encourages inland groundwater producers to increase pumping and coastal producers to decrease pumping to reduce the groundwater basin drawdown at the coast and protect against seawater intrusion. Inland pumpers can pump above the BPP without having to pay the full BEA for the amount pumped above the BPP (OCWD, 2015). Coastal pumpers receive BEA revenue from OCWD to assist in offsetting their additional water supply cost from taking less groundwater. OCWD Groundwater Reliability Plan To adapt to the substantial growth in water demands in OCWD's management area, it is paramount to anticipate and understand future water demands and develop projects to increase future water supplies proactively to match demands.The Groundwater Reliability Plan (GRP) is a continuation of these planning efforts that estimates the OC Basin's sustainable average annual production and extrapolates water needs of the OC Basin by combining recently completed water demand projections, and modeling of Santa Ana River flows available for recharge.These data will be used to evaluate future water supply projects and guide management of the OC Basin. The OC Basin is unadjudicated and is therefore subject to implementation of a GSP. DWR approved an alternative to a GSP for the OC Basin. The alternative plan was submitted to DWR to meet requirements of the SGMA and demonstrate how water managers have already achieved or will achieve sustainable groundwater management. DWR received 15 alternative plans and 9 were approved.The alternative report that was approved by DWR, entitled "Basin 8-1 Alternative," was prepared in collaboration with the City of La Habra and Irvine Ranch Water District. OCWD has an adopted Groundwater Management Plan but elected to create a new report in a format that mirrors a GSP,which is required under SGMA. Current water demand projections show a relatively slow increase over the 25-year planning horizon, which is generally of similar magnitude as the additional production from the GWRS since its final expansion in early 2023 to 130 mgd. This locally controlled, drought proof supply of water reduces the region's dependence on imported water. Historically,the Santa Ana River has served as the primary source of water to recharge the OC Basin.To determine the availability of future Santa Ana River flows, OCWD utilized surface water flow modeling of the upper watershed. Modeling was developed to predict the impacts future stormwater capture and wastewater recycling projects in the upper watershed would have on future Santa Ana River flow rates at Prado Dam. Santa Ana River base flows are expected to decrease as more water recycling projects are built in the upper watershed. OCWD continues to work closely with the US Army Corps of Engineers (USACE) to temporarily impound and slowly release up to approximately 20,000 AF of stormwater in the Prado Dam Conservation Pool.To some extent, the losses in baseflow are partially offset through the capture of additional stormwater held in the Prado Dam Conservation Pool.When available, OCWD will continue to augment groundwater recharge through the purchase of imported water through MET. OCWD will diligently monitor and evaluate future water supply projects to sustainably manage and protect the OC Basin for future generations. Specifically, in April 2021 USACE modified the Interim Water Control Manual change to allow 505 feet year-round,formalizing the higher pool and associated release operations used for conservation. And in February 2025, the USACE approved a new minor deviation permitting temporary storage up to elevation 508 feet, with potential future increases evaluated to 510 to 512 feet, enabling capture of roughly 2 billion gallons more stormwater and corresponding managed release rates tailored to OCWD's recharge capacity. CITY OF SANTA ANA