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

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Santa Ana 2020 Urban Water Management Plan arcadis.com 5-14 recharge of recycled water into the OC Basin by OCWD, historically through Water Factory 21 (WF-21), and now by the Groundwater Replenishment System (GWRS). Water suppliers must report baseline water use for two baseline periods, the 10- to 15-year baseline (baseline GPCD) and the five-year baseline (target confirmation) as described below. 5.1.1 Ten to 15-Year Baseline Period (Baseline GPCD) The first step to calculating the City’s water use targets is to determine its base daily per capita water use (baseline water use). The baseline water use is calculated as a continuous (rolling) 10-year average during a period, which ends no earlier than December 31, 2004 and no later than December 31, 2010. Water suppliers whose recycled water made up 10% or more of their 2008 retail water delivery can use up to a 15-year average for the calculation. The City did not have recycled water use in 2008; therefore, a 10-year baseline period is used. The City’s baseline water use is 130 GPCD, obtained from the 10-year period July 1, 1995 to June 30, 2005. 5.1.2 Five-Year Baseline Period (Target Confirmation) Water suppliers are required to calculate water use, in GPCD, for a five-year baseline period. This number is used to confirm that the selected 2020 target meets the minimum water use reduction requirements. Regardless of the compliance option adopted by the City, it will need to meet a minimum water use target of 5% reduction from the five-year baseline water use. This five-year baseline water use is calculated as a continuous five-year average during a period, which ends no earlier than December 31, 2007 and no later than December 31, 2010. The City’s five-year baseline water use is 122 GPCD, obtained from the five-year period July 1, 2003 to June 30, 2008. 5.1.3 Service Area Population The City’s service area boundaries correspond with the boundaries for a city or census designated place. This allows the City to use service area population estimates prepared by the DOF. CDR is the entity which compiles population data for Orange County based on DOF data. The calculation of the City’s baseline water use and water use targets in the 2010 UWMP was based on the 2000 U.S. Census population numbers obtained from CDR. The baseline water use and water use targets in the 2015 UWMP were revised based on the 2010 U.S. Census population obtained from CDR in 2012. That baseline remained in use in the 2020 calculations. SBx7-7 Water Use Targets In the 2020 UWMP, the City may update its 2020 water use target by selecting a different target method than what was used previously. The target methods and determination of the 2015 and 2020 targets are described below. The City selected Option 3 consistent with 2015 and maintained the same 2015 and 2020 target water uses as reported in its 2015 UWMP.