Water Quality Conditions in the Sacramento-San Joaquin Delta during 1995

California Department of Water Resources (DWR) | August 1st, 1999

Water year 1995 was a wet year, ending an eight-year period of predominantly dry and critically dry years.  After a relatively dry fall, January and March precipitation

Water year 1995 was a wet year, ending an eight-year period of predominantly dry and critically dry years.  After a relatively dry fall, January and March precipitation was heavy and produced flooding in the Central Valley.  By May 1, precipitation was 165% of average, snowpack water content was 215% af average, seasonal runoff was 170% of average, and reservoir storage was 110% of average. In 1995, the Net Delta Outflow Index (NDOI) was used to estimate Delta outflow, and the Sacramento and San Joaquin River Unimpaired Runoff indices were used to determine water year type for 1995.  Using these indices, water year 1995 was officially classified as wet on May 1, 1995.  All standards, including those in Water Right Decision 1485, as amended by the 1995 Water Quality Control Plan, were met in 1995. The entire 1995 calendar year was characterized by excess conditions, and both State Water Project and Central Valley Project water requirements were met as well as in-Delta consumptive uses.  Delta outflows were high throughout the year, and the calculated average monthly flows exceeded 80,000 cubic feet per second (CFS) during the peak outflow period (January through May), and 3,000 cfs during the minimum outflow period (July through November).

Water Quality Control Plan for Salinity (draft)

California State Water Resources Control Board (SWRCB) | October 15th, 1988

Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Watershed (Draft)

California State Water Resources Control Board (SWRCB) | July 25th, 2025

The State Water Resources Control Board (State Water Board or Board) has previously adopted water quality control plans and policies to protect water quality and control

The State Water Resources Control Board (State Water Board or Board) has previously adopted water quality control plans and policies to protect water quality and control the water resources that affect the beneficial uses of the Bay-Delta. These plans and policies were adopted consistent with section 13000 et seq. of the California Water Code and pursuant to the authority contained in section 13170. This Water Quality Control Plan covers the Bay-Delta estuary and tributary watersheds (Bay-Delta Plan or plan). The State Water Board will periodically review this plan, as discussed in section 4.6, pursuant to Water Code section 13240, to ensure that it provides reasonable protection for the designated beneficial uses. A summary description of the most recent updates to the plan are provided in section 1.4. 1 Current and previous versions of the Bay-Delta Plan and supporting documents are available at: 

Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Watershed (Draft)

California State Water Resources Control Board (SWRCB) | August 19th, 2026

A water quality control plan consists of: (1) beneficial uses to be protected; (2) water quality objectives for the reasonable protection of beneficial uses; and (3) a pr

A water quality control plan consists of: (1) beneficial uses to be protected; (2) water quality objectives for the reasonable protection of beneficial uses; and (3) a program of implementation for achieving the water quality objectives. This Plan establishes water quality objectives for which implementation can be accomplished by assigning responsibility to water right holders and water users to mitigate for the effects on the designated beneficial uses of their diversions and use of water. Together, the beneficial uses and the water quality objectives established to reasonably protect the beneficial uses are called water quality standards under the terminology of the federal Clean Water Act. Related documents: Main Draft Report Final Staff Report in Support of Sacramento/Delta Updates to the Bay-Delta Plan Appendix G2: Final Scientific Basis Report Supplement in Support of,Proposed Voluntary Agreements for the Sacramento River, Delta, and Tributaries Update to the San Francisco Bay/Sacramento-San Joaquin Delta Water Quality Control Plan State Water Resources Control Board Index page

Water quality measurements in San Francisco Bay by the U.S. Geological Survey, 1969–2015

Nature Portfolio (Springer Nature) | August 8th, 2017

The U.S. Geological Survey (USGS) maintains a place-based research program in San Francisco Bay (USA) that began in 1969 and continues, providing one of the longest reco

The U.S. Geological Survey (USGS) maintains a place-based research program in San Francisco Bay (USA) that began in 1969 and continues, providing one of the longest records of water-quality measurements in a North American estuary. Constituents include salinity, temperature, light extinction coefficient, and concentrations of chlorophyll-a, dissolved oxygen, suspended particulate matter, nitrate, nitrite, ammonium, silicate, and phosphate. We describe the sampling program, analytical methods, structure of the data record, and how to access all measurements made from 1969 through 2015. We provide a summary of how these data have been used by USGS and other researchers to deepen understanding of how estuaries are structured and function differently from the river and ocean ecosystems they bridge.

Water Quality Science in the Sacramento-San Joaquin Delta: Chemical Contaminants and Nutrients

Delta Stewardship Council (Delta Council) | July 26th, 2018

This review focuses on contaminants and nutrients in the Sacramento-San Joaquin Delta (the Delta), and on how findings about them have been sometimes used and sometimes n

This review focuses on contaminants and nutrients in the Sacramento-San Joaquin Delta (the Delta), and on how findings about them have been sometimes used and sometimes neglected in decisions related to ecosystem health in the Delta. The review considers water quality measurements made both in support of basic research and as part of routine monitoring studies in the Delta. However, the topic of monitoring per se is not comprehensively covered in this review because the Delta ISB is in the initial stages of reviewing the extensive monitoring enterprise in the Delta. This review of water quality is based on responses to a questionnaire sent to government agencies and science programs, interviews with water quality specialists and users of water quality data, relevant scientific publications, presentations observed in workshops and conferences, and public comments received on draft versions of the review. While we sought input from a broad range of stakeholders, we do not assume that we received a complete range of perceptions about this important issue. Additionally, water quality research and monitoring efforts are constantly evolving in the Delta, and several new programs and improvements were made as this review was being researched and prepared. This review should be considered to be part of an ongoing process by the Delta ISB.

Water Resources Development and Protection [Proposition 8]

LA Law Library (LALaw) | November 4th, 1980

Water Right Compliance and Enforcement in the Delta

California State Water Resources Control Board (SWRCB) | April 5th, 2012

The report focuses on the State Water Board’s responsibility to enforce water rights and to prevent unauthorized diversions of water in the state of California. Purs

The report focuses on the State Water Board’s responsibility to enforce water rights and to prevent unauthorized diversions of water in the state of California. Pursuant to the Water Code, the State Water Board is responsible for enforcing the terms and conditions of water right permits, licenses, and registrations, as well as investigating diversions of water. As addressed in the Strategic Workplan for Activities in the San Francisco Bay / Sacramento-San Joaquin Delta Estuary, the State Water Board is directed to investigate illegal diversions and violations of permit and license conditions and take action when violations are occurring in the Bay-Delta Watershed. The report discusses how the State Water Board began an investigation of illegal diversions of water, focusing on the Delta. For instance, the State Water Board has investigated two islands in the Delta to establish whether the landowners possessed any water rights. Most did, though some individuals were subject to more review, the majority of which concerned validating riparian claims for severed parcels. The report notes that the State Water Board has also investigated diverters within an area of the southern Delta and resolved all cases resulting from that investigation. The report also discusses how the State Water Board has begun an investigation of water diverters, statewide, who have failed to file required reports, which include the annual reports for permit and license holders, and the supplemental statements. Finally, the report suggests a new approach of looking at districts in the Delta who serve water to individuals, in addition to looking at compliance issues related to individual diverters.

Water Right Decision 1485: Sacramento-San Joaquin Delta and Suisun Marsh

California State Water Resources Control Board (SWRCB) | August 16th, 1978

Water shortage risks from perennial crop expansion in California's Central Valley

Environmental Research Letters (IOP) | October 15th, 2019

California's Central Valley is one of the world's most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports from

California's Central Valley is one of the world's most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports from a vast network of reservoirs and canals as well as groundwater, which has been substantially overdrafted to support irrigation. The region has undergone a shift to perennial (tree and vine) crops in recent decades, which has increased water demand amid a series of severe droughts and emerging regulations on groundwater pumping. This study quantifies the expansion of perennial crops in the Tulare Lake Basin, the southern region of the Central Valley with limited natural water availability. A gridded crop type dataset is compiled on a 1 mi2 spatial resolution from a historical database of pesticide permits over the period 1974–2016 and validated against aggregated county-level data. This spatial dataset is then analyzed by irrigation district, the primary spatial scale at which surface water supplies are determined, to identify trends in planting decisions and agricultural water demand over time. Perennial crop acreage has nearly tripled over this period, and currently accounts for roughly 60% of planted area and 80% of annual revenue. These trends show little relationship with water availability and have been driven primarily by market demand. From this data, we focus on the increasing minimum irrigation needs each year to sustain perennial crops. Results indicate that under a range of plausible future regulations on groundwater pumping ranging from 10% to 50%, water supplies may fail to consistently meet demands, increasing losses by up to 30% of annual revenues. More broadly, the datasets developed in this work will support the development of dynamic models of the integrated water-agriculture system under uncertain climate and regulatory changes to understand the combined impacts of water supply shortages and intensifying irrigation demand.