Reso25 16294 - Laserfiche WebLink

Browse Search

4 The reliability of the SFPUC RWS supply is highly dependent on the assumption of whether or not the 2018 Bay- Delta Plan Amendment is implemented. The Bay-Delta Plan Amendment was adopted in December 2018 by the State Water Resources Control Board (SWRCB) to establish water quality objectives to maintain the health of the Bay-Delta ecosystem. The adopted Bay-Delta Plan Amendment was developed with the stated goal of increasing salmonid populations in three San Joaquin River tributaries (the Stanislaus, Merced, and Tuolumne Rivers) and the Bay-Delta. The Bay-Delta Plan Amendment requires the release of 40 percent of the “unimpaired flow” on the three tributaries from February through June in every year type, whether wet, normal, dry, or critically dry. The implementation of the Bay-Delta Plan Amendment significantly impacts the SFPUC RWS supply reliability in dry years; however, the actual implementation of the Bay-Delta Plan Amendment is uncertain, as further explained in this WSA. Because of the uncertainties surrounding the implementation of the Bay-Delta Plan Amendment, this WSA presents findings for two scenarios, one assuming the Bay-Delta Plan Amendment is implemented and one assuming that the Bay-Delta Plan Amendment is not implemented. Under the scenario where it is assumed the Bay-Delta Plan Amendment is implemented, the total projected water supplies determined to be available for the Proposed Project in normal years will meet the projected water demand associated with the Proposed Project, in addition to the City’s existing and planned future uses through 2045. However, with the implementation of the Bay-Delta Plan Amendment, significant supply shortfalls are projected in dry years for agencies that receive water supplies from the SFPUC RWS, as well as other agencies whose water supplies would be affected by the Amendment. For the City, total supply shortfalls (i.e., for combined potable and recycled water) are projected in single dry years (ranging from 32 to 40 percent) and in multiple dry years (ranging from 32 to 47 percent) through 2045. If supply shortfalls do occur, the City expects to meet these supply shortfalls through water demand reductions and other shortage response actions by implementation of its Water Shortage Contingency Plan (WSCP), which was adopted on June 14, 2021 and is included in Chapter 8 of the City’s 2020 UWMP. With the implementation of the Bay-Delta Plan Amendment, the projected single dry year shortfalls would require implementation of Stage 4 or 5 of the City’s WSCP, while the projected multiple dry year shortfalls would require implementation of Stage 4, 5 or 6 of the City’s WSCP. The City’s 2020 UWMP included projected water demand sufficient to accommodate 30% the demand for Proposed Project. The remaining demand for the project is within the available water supply for the City and would not change the level of water shortage the City may need to declare in single or multiple dry years. Additionally, the Project would be subject to the same water conservation and water use restrictions as other water users within the City’s system. Under the scenario where it is assumed the Bay-Delta Plan Amendment is not implemented, the total projected water supplies determined to be available for the Proposed Project in normal years will meet the projected water demand associated with the Proposed Project, in addition to the City’s existing and planned future uses through 2045. During single dry years and multiple dry years, supply shortfalls are projected for the City, but they are significantly less than the projected supply shortfalls if the Bay-Delta Plan Amendment is implemented. Supply shortfalls for both single dry years (ranging from 1 to 2 percent) and multiple dry years (ranging from 1 to 11 percent) are projected through 2045. ATTY/RESO.0027/CC RESO WATER SUPPLY ASSESSMENT (920 SHASTA) - EXHIBIT A REV: 04-22-25 VR Page 4 of 42