Item 28 - Urban Water Management Plan and Water Shortage Contingency Plan

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Santa Ana 2020 Water Shortage Contingency Plan 3-5 water, and 1% recycled water. It is projected that by 2045, the water supply portfolio will change to approximately 84% groundwater, 15% imported water, and 1% recycled water, reflecting the increase in OCWD’s BPP to 85% beginning in 2025 (Santa Ana, 2021a). Unconstrained Customer Demand The WSCP and Annual Assessment define unconstrained demand as expected water use prior to any projected shortage response actions that may be taken under the WSCP. Unconstrained demand is distinguished from observed demand, which may be constrained by preceding, ongoing, or future actions, such as emergency supply allocations during a multi-year drought. WSCP shortage response actions to constrain demand are inherently extraordinary; routine activities such as ongoing conservation programs and regular operational adjustments are not considered as constraints on demands. The City’s DRA reveals that its supply capabilities are expected to balance anticipated total water use and supply, assuming a five-year consecutive drought from FY 2020-21 through FY 2024-25 (Santa Ana, 2021a). Water demands in a five-year consecutive drought are calculated as a six percent increase in water demand above a normal year for each year of the drought (CDM Smith, 2021). Planned Water Use for Current Year Considering Dry Subsequent Year Water Code Section 10632(a)(2)(B)(ii) requires the Annual Assessment to determine “current year available supply, considering hydrological and regulatory conditions in the current year and one dry year.” The Annual Assessment will include two separate estimates of the City’s annual water supply and unconstrained demand using: 1) current year conditions, and 2) assumed dry year conditions. The Annual Assessment will include two separate estimates of City’s annual water supply and unconstrained demand using: 1) current year conditions, and 2) assumed dry year conditions. Accordingly, the Annual Assessment’s shortage analysis will present separate sets of findings for the current year and dry year scenarios. The Water Code does not specify the characteristics of a dry year, allowing discretion to the Supplier. The City will use its discretion to refine and update its assumptions for a dry year scenarios in each Annual Assessment as information becomes available and in accordance with best management practices. Supply and demand analyses for the single-dry year case was based on conditions affecting the SWP as this supply availability fluctuates the most among MET’s, and therefore the City’s sources of supply. FY 2013-14 was the single driest year for SWP supplies with an allocation of 5% to Municipal and Industrial (M&I) uses. Unique to this year, the 5% SWP allocation was later reduced to 0%, before ending up at its final allocation of 5%, highlight the stressed water supplies for the year. Furthermore, on January 17, 2014 Governor Brown declared the drought State of Emergency citing 2014 as the driest year in California history. Additionally, within Orange County, precipitation for FY 2013-14 was the second lowest on record, with 4.37 inches of rain, significantly impacting water demands. The water demand forecasting model developed for the Demand Forecast TM isolated the impacts that weather and future climate can have on water demand through the use of a statistical model. The impacts of hot/dry weather conditions are reflected as a percentage increase in water demands from the normal year condition (average of FY 2017-18 and FY 2018-19). For a single dry year condition (FY 2013-14), the model projects a 6% increase in demand for the OC Basin area where the City’s service area is located (CDM Smith, 2021). Detailed information of the model is included in the City’s 2020 UWMP.