Long-Term Operation of the State Water Project in the Sacramento-San Joaquin Delta, Suisun Marsh, and Suisun Bay

DWR is proposing to modify actions to improve SWP operational flexibility while maintaining similar or equal level of protection proportional to SWP impacts, particularly given recent and best available scientific findings, the status of the historical and supplemented Delta Smelt population. Additionally, recent modifications of joint actions for Fall X2 for the CVP and SWP (U.S. Bureau of Reclamation 2025) occurred. DWR proposes to modify COA 9.1.3 Delta Smelt Summer-Fall Action in exchange for additional alternative actions in COA 9.1.3 and COA 9.1.4 that are expected to provide equal or better benefits to the species. This approach is consistent with the initial 2008 FWS application of Fall X2 as adaptive management to determine whether a benefit could manifest that would help Delta Smelt survival. The anticipated benefits provided through the Fall X2 requirement have not, after several years, manifested in a meaningful benefit, so other approaches to generating a benefit should be attempted. The proposed major amendment, together with ongoing monitoring and data collection consistent with the adaptive management approach, is more likely to achieve the intended benefit of food supply during a time when Delta Smelt may be present, as explained further below. The proposed major amendment is also consistent with the limited term amendment to the ITP for the 2025 water year (2081-2023-054-00-A1). Proposed Modifications and Alternative Actions COA 9.1.3 Proposed modification of COA 9.1.3 includes a permanent removal of the September and October Fall X2 requirement (80 km) as described in the 2024 LTO ITP, instead operating to SWRCB D-1641 for September and October, consistent with the limited term amendment (CDFW 2025a). DWR proposes an alternative action to mitigate SWP impacts by flooding approximately 315 acres of wetlands during the summer and fall of Wet and Above Normal water years to provide food subsidies in Suisun Marsh where juvenile Delta Smelt have been abundant historically. Changes to the food action region may be proposed by DWR, in coordination with CDFW, if monitoring data of Delta Smelt suggest a food action may have benefits outside the Suisun Marsh region. This alternative action is estimated to provide a biomass of zooplankton equal to the SWP’s proportional share of the biomass of Delta Smelt’s main diet taxon, Pseudodiaptomus forbesi, transported during a Fall X2 action. COA 9.1.4 Proposed modification of COA 9.1.4 includes an additional condition “9.1.4.2 Delta Smelt Survival Evaluation and Enhancement Plan” with the goal to improve Delta Smelt survival and abundance, and the production of hatchery smelt for applied science activities. Activities may include development of key research questions and implementation of hypothesis-driven studies to inform process improvements to the Delta Smelt Supplementation Program. These activities are complementary to, but distinct from, Supplementation Program releases. Project Location The project location for the Proposed Project is the same as described in the 2023 ITPA (ICF 2023:3-1–3-2) and 2024 LTO ITP (California Department of Fish and Wildlife 2024:2).