14 ATTACHMENT 1 EXHIBIT A - Laserfiche WebLink

Chapter 6 Water Supply Characterization THE CITY OF PL£ASANTON DWR's estimates of SWP deliveries are based on a computer model that simulates monthly operations of the SWP and Central Valley Project (CVP) systems. Key inputs to the model include system facilities, hydrologic inflows to the system, regulatory and operational constraints on system operations, and contractor demands for SWP water. In conducting its model studies, DWR must make assumptions regarding each of these key inputs. In the 2019 DCR model for existing (2020) conditions, DWR assumed: existing facilities, hydrologic inflows to the model based on 82 years of historical inflows (1922 through 2003), current regulatory and operational constraints, and contractor demands at maximum Table A amounts. Note that the regulatory and operational constraints include the 2018 Coordinated Operations Agreement (COA) Amendment, 2019 Biological Opinions, and 2020 Incidental Take Permit. The 2018 COA Amendment lays out the terms under which the CVP operates with the SWP. The 2019 Biological Opinions for the Long -Term Operation of the CVP and SWP reflect the federal government's (U.S. Fish and Wildlife Service's) opinion as to whether or not the operation of the CVP and SWP is likely to jeopardize the continued existence of threatened and endangered species or result in the destruction or adverse modification of critical habitat. Finally, the 2020 Incidental Take Permit is a requirement for the SWP's California Endangered Species Act compliance with regards to state -protected longfin smelt and state- and federally -protected delta smelt, winter -run Chinook, and spring -run Chinook. To evaluate SWP supply availability under future conditions, the 2019 DCR included a model study representing hydrologic and sea level rise conditions at 2040. The future condition study used all of the same model assumptions as the study under existing conditions but reflected changes expected to occur from climate change, specifically, projected temperature and precipitation changes centered around 2035 (2020 to 2049) and a 45 cm sea level rise. For Zone 7's Table A supply, the 2019 DCR's existing condition was assumed to represent 2020 (59 percent of Table A reliability, 47,600 AFY)Z, and the future condition (54 percent of Table A reliability, 43,500 AFY)z was applied to 2040; the years in between were interpolated between these two bookends'. Note that the effect of the proposed Delta Conveyance Project on SWP water supply yield is still being analyzed and has not been included. As a SWP contractor, Zone 7 has the option to store unused Table A water from one year to the next in the SWP's San Luis Reservoir, when there is storage capacity available. This "carryover" water is also called Article 12e or 56c water, in reference to the relevant contract terms. Article 12e water must be taken by March 31 of the following year, but Article 56c water may remain as carryover as long as San Luis Reservoir storage is available. The analysis in Zone 7's UWMP assumes Zone 7 carries over 10,000 AF of water each year on average. 6.2.1.2.1.3 Article 21 Water (Interruptible or Surplus Water) Under Article 21 of Zone 7's SWP contract, Zone 7 also has access to excess water supply from the SWP that is available only if: 1) it does not interfere with SWP operations or Table A allocations, 2) excess water is available in the Delta, and 3) it will not be stored in the SWP system. As described in the 2019 DCR, z Existing condition: Table A-4 of the Technical Addendum to the 2019 DCR. Future condition: Table B-6. 3 For comparison, the Zone 7's 2015 UWMP assumed 62 percent of Table A reliability (50,000 AFY). The 2019 WSE Update assumed 49 percent of Table A reliability (39,500 AF). Table A allocations over the last ten years have ranged between 5 percent and 85 percent, with an average of 48 percent. WEST YOST 6-4 City of Pleasanton 2020 Urban Water Management Plan N-e80-60-20-04-wP-a-680-2020uwMP May 2021