Review of Science Used to Estimate Water Supply Reliability Involving the Delta

Delta Stewardship Council (Delta Council) | April 3rd, 2018

Review of SWRCB’s “Working Draft Scientific Basis Report for New and Revised Flow Requirements on the Sacramento River and Tributaries, Eastside Tributaries to the Delta, Delta Outflow, and Interior Delta Operations”

Delta Stewardship Council (Delta Council) | February 23rd, 2017

Insightful, informative, well-illustrated, clearly written—these are among our overall impressions of “Working Draft Scientific Basis Report for New and Revised Flow

Insightful, informative, well-illustrated, clearly written—these are among our overall impressions of “Working Draft Scientific Basis Report for New and Revised Flow Requirements on the Sacramento River and Tributaries, Eastside Tributaries to the Delta, Delta Outflow, and Interior Delta Operations”. The comments below focus on recommended improvements. In particular, we recommend clarifying, and further justifying scientifically, the proposed use of percent of “unimpaired flow” as the main basis for establishing an annual environmental water budget. We also suggest presenting a further review of cold-water management, a deeper analysis of non-flow stressors, additional consideration of near-term responses to climate change, and elaboration of how regulations managed adaptively may improve scientific understanding of environmental flows.

Review of the Draft 2022-2026 Science Action Agenda

Delta Stewardship Council (Delta Council) | January 28th, 2022

Review of the Draft Environmental Impact Report for the Delta Conveyance Project

Delta Stewardship Council (Delta Council) | December 16th, 2022

Review of the Interagency Ecological Program

Delta Stewardship Council (Delta Council) | January 29th, 2018

Review of the Long-Term Operations of the Central Valley Project and the State Water Project

National Academy of Sciences (NAS) | November 10th, 2025

The CVP and SWP (referred to collectively as “the Projects”) rarely deliver their full contracted  amount of water. Some of this is inherent in the operation of larg

The CVP and SWP (referred to collectively as “the Projects”) rarely deliver their full contracted  amount of water. Some of this is inherent in the operation of large water projects with diverse demands in a dry and highly variable climate. A growing, complex regulatory environment of state and federal laws, some of which were created to protect fish species endemic to the Delta, has further restricted CVP and SWP operations.  These fish include the southern distinct population segment of North American green sturgeon, California Central Valley steelhead, Central Valley spring-run Chinook salmon, Sacramento River winter-run Chinook salmon, longfin smelt, and Delta smelt. Operating the Projects while trying to prevent species extinction can be a source of conflict if the actions to prevent extinction reduce the amount of water that can be exported. Project operation into the future will likely become more challenging as changes in various climatic factors push the listed species closer to their thresholds of survivability. Hence, in late 2023 USBR contracted with the National Academies of Sciences, Engineering, and Medicine (NASEM) to form an expert committee that could serve as an independent review for the CVP and SWP as they operate into the future. The Committee’s statement of task appears in Box S-1. The three actions chosen for the study—the Shasta Coldwater Pool Management Action, the Old and Middle River Flow Management Action, and the Summer-Fall Habitat Action for Delta Smelt— are perceived as consequential for species survival and controversial for their effects on water deliveries to contractors.

Review of the Monitoring Enterprise in the Sacramento-San Joaquin Delta

Delta Stewardship Council (Delta Council) | March 3rd, 2022

Review of the Monitoring Enterprise in the Sacramento-San Joaquin Delta Summary Sheet

Delta Stewardship Council (Delta Council) | April 28th, 2022

Review of Water Supply Reliability Estimation Related to the Sacramento-San Joaquin Delta

Delta Stewardship Council (Delta Council) | June 16th, 2022

Revised Incidental Take Methodology for the Coordinated Long-Term Operation of the CVP and SWP

U.S. Fish and Wildlife Service (FWS) | January 30th, 2019