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

The purpose of this document is to present NOAA’s National Marine Fisheries Service’s (NMFS) biological and conference opinion (Opinion), about whether the U.S. Burea

The purpose of this document is to present NOAA’s National Marine Fisheries Service’s (NMFS) biological and conference opinion (Opinion), about whether the U.S. Bureau of Reclamation’s (Reclamation) proposed long-term operations of the Central Valley Project (CVP), operated in coordination with the State Water Project (SWP; hereafter referred to as CVP/SWP operations, the proposed action, or the project), is likely to jeopardize the continued existence of the following species  Endangered Sacramento River winter-run Chinook salmon (Oncorhynchus tshawytscha, hereafter referred to as winter-run)  Threatened Central Valley spring-run Chinook salmon (O. tshawytscha, hereafter referred to as spring-run)  Threatened Central Valley (CV) steelhead (O. mykiss)  Threatened Central California Coast (CCC) steelhead (O. mykiss)  Threatened Southern Distinct Population Segment (DPS) of North American green sturgeon (Acipenser medirostris, hereafter referred to as Southern DPS of green sturgeon)  Endangered Southern Resident killer whales (Orcinus orca, hereafter referred to as Southern Residents)  or destroy or adversely modify the designated critical habitat of the above salmon and steelhead species, or proposed critical habitat for Southern DPS of green sturgeon. This Opinion is based on the best scientific and commercial information available. 

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

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

Biological opinion on the coordinated operations of the Central Valley Project (CVP) and State Water Project (SWP)

U.S. Fish and Wildlife Service (FWS) | December 15th, 2008

On May 16, 2008, the U.S. Bureau of Reclamation and the California Department of Water Resources asked the Service to initiate consultation on the Long-Term Operational C

On May 16, 2008, the U.S. Bureau of Reclamation and the California Department of Water Resources asked the Service to initiate consultation on the Long-Term Operational Criteria and Plan (OCAP) for coordination of the Central Valley Project and State Water Project, specifically concerning the delta smelt and its critical habitat. (See OCAP Legal Archives.) On December 15, 2008, the Fish & Wildlife Service issued a biological opinion (BO) on the Long-Term Operational Criteria and Plan (OCAP) for coordination of the Central Valley Project and State Water Project. The Service determined that the continued operation of these two water projects, as described in the plan, was likely to jeopardize the continued existence of the delta smelt and adversely modify its critical habitat. The inclusion by the Service of reasonable and prudent alternatives, and their acceptance by the water agencies, avoided jeopardy and adverse modification.

Brackish Water Desalination Facility Project

Delta Stewardship Council (Delta Council) | April 1st, 2020

The City of Antioch (City) is proposing the Brackish Water Desalination Project (Project), which consists of the construction of a desalination facility at the City’s

The City of Antioch (City) is proposing the Brackish Water Desalination Project (Project), which consists of the construction of a desalination facility at the City’s water treatment plant (WTP) with the capacity to produce up to 6 million gallons per day (mgd) of finished water; demolition of the existing San Joaquin River intake pump station; construction of a new intake pump station; approximately 3,000 feet of pipeline from the existing raw water pipeline underneath Lone Tree Way to the City’s WTP to allow a direct connection to maximize use of existing infrastructure; and approximately 4 miles of pipeline from the desalination facility to the Delta Diablo wastewater treatment plant (WWTP) to discharge brine with the WWTP effluent through the existing Delta Diablo outfall to New York Slough. The Project facilities would be located in the cities of Antioch and Pittsburg, California (Figure 1), at the western edge of the San Joaquin- Sacramento Delta (Delta). The main objectives of the Project are to improve water supply reliability and water quality for its customers; develop a reliable and drought-resistance water source to reduce dependency on purchased water supplies; maximize and preserve the use of the City’s pre-1914 water rights; and provide cost effective operational flexibility for the City.

Bulletin 132-00 Management of the California State Water Project

California Department of Water Resources (DWR) | December 3rd, 2001

Bulletin 132-01 Management of the California State Water Project

California Department of Water Resources (DWR) | December 1st, 2002

Bulletin 132-02 Management of the California State Water Project

California Department of Water Resources (DWR) | January 5th, 2004