Annual Report of Activities October 1, 2013, to September 30, 2014, Delta Operations for Salmonids and Sturgeon (DOSS) Technical Working Group

Delta Stewardship Council (Delta Council) | October 31st, 2014

Annual Report of Activities Water Year 2018 Stanislaus Operations Group (SOG)

Delta Stewardship Council (Delta Council) | November 1st, 2018

Annual Report of Activities, October 1, 2013 to September 30, 2014, Stanislaus Operations Group (SOG)

Delta Stewardship Council (Delta Council) | September 30th, 2014

August 2025 Most Probable 24-Month Study

U.S. Bureau of Reclamation (USBR) | August 15th, 2025

The August 2024 24-Month Study projected the January 1, 2025, Lake Mead elevation to be below 1,075 feet and above 1,050 feet. Consistent with Section 2.D.1 of the Interi

The August 2024 24-Month Study projected the January 1, 2025, Lake Mead elevation to be below 1,075 feet and above 1,050 feet. Consistent with Section 2.D.1 of the Interim Guidelines, a Shortage Condition consistent with Section 2.D.1.a will govern the operation of Lake Mead for calendar year (CY) 2025. In addition, Section III.B of Exhibit 1 to the Lower Basin Drought Contingency Plan (DCP) Agreement will also govern the operation of Lake Mead for CY 2025. Lower Basin projections for Lake Mead take into consideration additional conservation efforts under the LC Conservation Program. The August 2025 24-Month Study projected the January 1, 2026, Lake Powell elevation to be less than 3,575 feet and at or above 3,525 feet and the Lake Mead elevation to be at or above 1,025 feet. Consistent with Section 6.C.1 of the Interim Guidelines, and Section 6.E of the 2024 Interim Guidelines SEIS ROD, the operational tier for Lake Powell in WY 2026 is the Mid-Elevation Release Tier and the water year release volume from Lake Powell is projected to be 7.48 maf. Given the hydrologic variability of the Colorado River System, the actual water year 2026 operations, and being consistent with Section 6.E of the 2024 Interim Guidelines SEIS ROD, the projected release from Lake Powell in water year 2026 may be less than 7.48 maf. The August 2025 24-Month Study projected the January 1, 2026, Lake Mead elevation to be below 1,075 feet and above 1,050 feet. Consistent with Section 2.D.1 of the Interim Guidelines, a Shortage Condition consistent with Section 2.D.1.a will govern the operation of Lake Mead for CY 2026. In addition, Section III.B of Exhibit 1 to the Lower Basin DCP Agreement will also govern the operation of Lake Mead for CY 2026. Lower Basin projections for Lake Mead take into consideration additional conservation efforts under the LC Conservation Program. The 2026 operational tier determinations for Lake Powell and Lake Mead will be documented in the 2026 AOP, which is currently in development. Related scenarios: August 2025 Probable Minimum 24-Month Study August 2025 Probable Maximum 24-Month Study

August 2025 Probable Maximum 24-Month Study

U.S. Bureau of Reclamation (USBR) | August 15th, 2025

In addition to the August 2025 24-Month Study based on the Most Probable inflow scenario, and in accordance with the Upper Basin Drought Response Operations Agreement (DR

In addition to the August 2025 24-Month Study based on the Most Probable inflow scenario, and in accordance with the Upper Basin Drought Response Operations Agreement (DROA), Reclamation has conducted additional model runs in August to determine a possible range of reservoir elevations. Probable minimum and probable maximum model runs are conducted in January, April, August, and October, or when necessary to incorporate changing conditions. The Probable Minimum inflow scenario reflects a dry hydrologic condition which statistically would be exceeded 90% of the time. The Most Probable inflow scenario reflects a median hydrologic condition which statistically would be exceeded 50% of the time. The Probable Maximum inflow scenario reflects a wet hydrologic condition which statistically would be exceeded 10% of the time. There is approximately an 80% probability that a future elevation will fall inside the range of the minimum and maximum inflow scenarios. Additionally, there are possible inflow scenarios that would result in reservoir elevations falling outside the ranges indicated in these reports. Related scenarios: August 2025 Most Probable 24-Month Study August 2025 Probable Minimum 24-Month Study

August 2025 Probable Minimum 24-Month Study

U.S. Bureau of Reclamation (USBR) | August 15th, 2025

In addition to the August 2025 24-Month Study based on the Most Probable inflow scenario, and in accordance with the Upper Basin Drought Response Operations Agreement (DR

In addition to the August 2025 24-Month Study based on the Most Probable inflow scenario, and in accordance with the Upper Basin Drought Response Operations Agreement (DROA), Reclamation has conducted additional model runs in August to determine a possible range of reservoir elevations. Probable minimum and probable maximum model runs are conducted in January, April, August, and October, or when necessary to incorporate changing conditions. The Probable Minimum inflow scenario reflects a dry hydrologic condition which statistically would be exceeded 90% of the time. The Most Probable inflow scenario reflects a median hydrologic condition which statistically would be exceeded 50% of the time. The Probable Maximum inflow scenario reflects a wet hydrologic condition which statistically would be exceeded 10% of the time. There is approximately an 80% probability that a future elevation will fall inside the range of the minimum and maximum inflow scenarios. Additionally, there are possible inflow scenarios that would result in reservoir elevations falling outside the ranges indicated in these reports. Related scenarios: August 2025 Most Probable 24-Month Study August 2025 Probable Maximum 24-Month Study  

Balancing Flood Risk and Water Supply in California: Policy Search Integrating Short-Term Forecast Ensembles With Conjunctive Use

American Geophysical Union (AGU) | September 24th, 2018

Short-term weather forecasts have the potential to improve reservoir operations for both flood control and water supply objectives, especially in regions currently relyin

Short-term weather forecasts have the potential to improve reservoir operations for both flood control and water supply objectives, especially in regions currently relying on fixed seasonal flood pools to mitigate risk. The successful development of forecast-based policies should integrate uncertainty from modern forecast products to create unambiguous rules that can be tested on out-of-sample periods. This study investigates the potential for such operating policies to improve water supply efficiency while maintaining flood protection, combining state-of-the-art weather hindcasts with downstream conjunctive use to transfer surplus flood releases to groundwater storage. Because available weather hindcasts are relatively short (10–20 years), we propose a novel statistical framework to develop synthetic forecasts over longer periods of the historical record. Operating rules are trained with a recently developed policy search framework in which decision rules are structured as binary trees. Policies are developed for a range of scenarios with varying forecast skill and conjunctive use capacity, using Folsom Reservoir, California, as a case study. Results suggest that the combination of conjunctive use and short-term weather forecasts can substantially improve both water supply and flood control objectives by allowing storage to remain high until forecasts trigger a release. Further, increased conjunctive use capacity reduces the importance of forecast skill, since surface storage can be moved to groundwater during the flood season without losing water supply. This analysis serves the development of forecast-based operating policies for large, multipurpose reservoirs in California and other regions with similar flood hydroclimatology.

Biological opinion and conference opinion on the long-term operations of the Central Valley Project and State Water Project

National Marine Fisheries Service (NMFS) | June 4th, 2009

Biological Opinion for the Reinitiation of Consultation on the Long-Term Operation of the Central Valley Project and State Water Project

National Marine Fisheries Service (NMFS) | December 6th, 2024

Biological Opinion on Long-term Operation of the Central Valley Project and the State Water Project

National Marine Fisheries Service (NMFS) | October 21st, 2019