2025 Spring Pulse Flow Release

2025 Spring Pulse Flow Release

Project Description: Oakdale Irrigation District (OID) and South San Joaquin Irrigation District (SSJID), collectively referred to as “Districts”, will provide up to 100,000 acre-feet of water to augment water releases made by the USBR to benefit migratory fish on the Stanislaus and San Joaquin Rivers. The water proposed to be released is surplus to the anticipated irrigation demand of each district. The releases will occur at Goodwin Dam during April and May 2025, and will be coordinated with the USBR’s releases to assist and supplement Reclamation flows in meeting their legal obligations for the April-May pulse flow under D-1641. The USBR will be responsible for determining the flow rate and schedule of the release, upon concurrence with the National Marine Fisheries Service (NMFS). The released water will be diverted by the Central Valley Project (CVP) and State Water Project Contractors (SWP) at the Jones and Banks pumping stations at a 1:1 ratio. Current Hydrology: Based on studies contracted by OID, projected hydrology at a 90% exceedance rate for the Stanislaus River Basin trends toward Dry for water year 2025, indicating an Appendix-2e base flow requirement of 185,000 acre-feet for water year March 1, 2025 to February 28, 2026. Reclamation’s April-May flows under Appendix-2e range from 200-1,400 cfs in the Stanislaus River while the Vernalis requirement under D-1641 is just over 3,000 cfs, leading to a significant deficit even when considering the inflow from other upstream releases. Baseline conditions were generated by incorporating an estimated 474 TAF combined diversion for both Districts, an 86 TAF diversion volume by CVP contractors, and Fish and Wildlife Releases of 199 TAF (Critical SRP) below Goodwin Dam. A total of 100 TAF was then incorporated into the April and May supplemental release parameter of the model. Under those conditions, the Stanislaus River Basin model indicates an End of Month Storage September in New Melones of 1.527 MAF. The Districts have determined there will be no impact to the cold water pool at New Melones due to the supplemental releases. Project Purpose: The releases are for the purpose of improving flow on the Stanislaus and San Joaquin Rivers to benefit migratory fish. Additionally, the Project will provide water for municipal, industrial, and agricultural uses in areas south of the Delta. Pursuant to the State Water Resources Control Board's (SWRCB) Decision 1641 (D-1641), the USBR is responsible for meeting the April-May flow objective flows at Vernalis. The NMFS 2019 Biological Opinion (BiOp) establishes the Spring “pulse flow” identified in the Stanislaus River Minimum Fish Flow Schedule for the purpose of protecting migratory fish in the lower San Joaquin River and Delta, particularly fall-run Chinook salmon and Central Valley steelhead. The USBR’s releases of the water provided by OID and SSJID will supplement flows in the Stanislaus and San Joaquin Rivers to improve instream flow conditions for migratory fish during April and May 2025. The released water will be diverted by the CVP and SWP contractors, similar to what had historically occurred under the WIIN Act, Section 4001. This water will help those entities offset allocation reductions they have received this year. Additionally, OID and SSJID will be paid for the water released at Goodwin Dam, which will in turn be used for capital improvements and ongoing operations and maintenance of each district.

Unincorporated Areas

Alameda, Calaveras, Contra Costa, Merced, San Joaquin, Stanislaus, Tuolumne

Countywide, Northern California, Unincorporated

Alameda, Calaveras, Contra Costa, Merced, San Joaquin, Stanislaus, Tuolumne