Water Quality Conditions in the Sacramento-San Joaquin Delta and Suisun and San Pablo Bays during 2009

California Department of Water Resources (DWR) | December 28th, 2010

This report summarizes the results of water quality monitoring and special  studies conducted by the Environmental Monitoring Program (EMP) within the Sacramento-San Joa

This report summarizes the results of water quality monitoring and special  studies conducted by the Environmental Monitoring Program (EMP) within the Sacramento-San Joaquin Delta (Delta) and Suisun and San Pablo bays (the upper San Francisco estuary) during calendar year 2009. This monitoring is mandated by Water Right Decision 1641 (D-1641) and this report is being submitted to fulfill the reporting requirements of this decision. The EMP monitored water quality using a protocol implemented in 1996. Under this monitoring protocol, 13 sampling sites—2 of which were added after 1996—representing 8 regions of the upper San Francisco estuary (estuary) were monitored for 15 physical and chemical water quality parameters. The results gathered from the sampling of these 15 parameters are described in this report. Parameters such as water temperature, Secchi disk depth, dissolved oxygen (DO) concentration, specific conductance, dissolved inorganic nitrogen, orthophosphate, and volatile suspended solids were within their historical range. Measured parameters exhibited seasonal variation as well as changes in response to significant rainfall events and in flow rates. In addition to monitoring physical and chemical water quality parameters, biological sampling was conducted to monitor the productivity and community composition of phytoplankton, zooplankton, and benthic communities.

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 Decision 1485: Sacramento-San Joaquin Delta and Suisun Marsh

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

Water Rights Decision 1641 (D-1641)

California State Water Resources Control Board (SWRCB) | December 29th, 1999

This decision is part of the SWRCB’s implementation of the 1995 Bay-Delta Plan. Many of the objectives in the 1995 Bay-Delta Plan are best implemented by making changes

This decision is part of the SWRCB’s implementation of the 1995 Bay-Delta Plan. Many of the objectives in the 1995 Bay-Delta Plan are best implemented by making changes in the flow of water or in the operation of facilities that move water. Accordingly, this decision amends certain water rights by assigning responsibilities to the persons or entities holding those rights to help meet the objectives.