San Joaquin River

The Pulse of the Bay 2022: 50 Years after the Clean Water Act

San Francisco Estuary Institute (SFEI) | October 13th, 2022

This August an algal bloom of historic proportions blanketed San Francisco Bay. The most concerning aspect of the bloom was the death of thousands of fish across wide are

This August an algal bloom of historic proportions blanketed San Francisco Bay. The most concerning aspect of the bloom was the death of thousands of fish across wide areas of the Bay, including 10,000 yellowfin goby, hundreds of striped bass and white sturgeon, and other species like green sturgeon, bat rays, and sharks. This is the most widespread and deadliest fish kill in the Bay in recent memory.

The Rainfall Intensity-Duration Control of Debris Flows After Wildfire

American Geophysical Union (AGU) | May 23rd, 2023

The Rebirth of California Fish & Game Code Section 5937: Water for Fish

University of California, Davis (UC Davis) | July 1st, 2012

Swarms of living creatures will live wherever the river flows. There will be large numbers of fish, because this water flows there and makes the salt water fresh; so wh

Swarms of living creatures will live wherever the river flows. There will be large numbers of fish, because this water flows there and makes the salt water fresh; so where the river flows everything will live. Fishermen will stand along the shore; from En Gedi to En Eglaim there will be places for spreading nets. In an average year, California receives inflows and imports of water totaling around 200 million acre-feet,2 enough water to cover the entire state twenty-three inches deep. But California is a state of spatial and temporal water extremes. Spatially, precipitation varies wildly: Death Valley in the Southeast averages less than three inches per year, yet the northwestern corner of the state averages over 140 inches per year. More than 70% of California’s stream flow originates north of Sacramento, but more than 80% of the water is used south of Sacramento. Temporally, precipitation varies both seasonally and annually. California’s wet season typically runs from October or November to April or May, with little or no precipitation during the growing season, from May to September.7 Annual rainfalls of 40% or more below average and 36% or more above average each typically occur once every six to seven years.  To balance these extremes, over 1,300 dams store water across the state, supplying water for urban, industrial, and agricultural uses. While these uses sustain a tremendous part of California’s economy, they also come at high, often unappreciated costs. Fish also need water, so dams that alter water flows for human benefits may also have marked negative impacts on fish.

The Relationship between California Rainfall and ENSO Events

American Meteorological Society (AMS) | November 1st, 1989

This paper examines the annual rainfall over California during 11 ENSO events within the period 1950 to 1982. During six of these, unusually wet conditions prevailed thro

This paper examines the annual rainfall over California during 11 ENSO events within the period 1950 to 1982. During six of these, unusually wet conditions prevailed throughout California; conditions were near normal during five events; and in one extreme drought occurred statewide. A comparison with the ENSO classification scheme of Fu et al, based on SST patterns in the Pacific, shows an excellent correspondence. Type 1 years, with large positive temperature anomalies east of the date line and lasting well into winter, are invariably events that enhance California rainfall. Normal years coincide with Type 2 ENSO events (moderate warming over a broad sector); the dry year is the sole Type 3 year, with weak anomalies confined to the eastern Pacific. This study also shows that the response to ENSO is regionally specific. Although throughout the state most years with extremely wet conditions are ENSO years, the tendency for an ENSO event to increase rainfall is greatest in Southern California, where 9 of 11 events produced above-normal rainfall and 8 of the 10 wettest years was an ENSO year. The pattern is more complex in central California; there ENSO years are almost invariably ones with highly abnormal rainfall, but they may be either wet or dry. The areas least influenced by ENSO are the Sierra Nevada and Northern California. The reasons for the geographical pattern of response become apparent when the seasonality and causes of rainfall in the various regions are evaluated.

The Role of Tidal Marsh Restoration in Fish Management in the San Francisco Estuary

University of California, Davis (UC Davis) | March 1st, 2014

Tidal marsh restoration is an important management issue in the San Francisco Estuary (estuary). Restoration of large areas of tidal marsh is ongoing or planned in the lo

Tidal marsh restoration is an important management issue in the San Francisco Estuary (estuary). Restoration of large areas of tidal marsh is ongoing or planned in the lower estuary (up to 6,000 ha, Callaway et al. 2011). Large areas are proposed for restoration in the upper estuary under the Endangered Species Act biological opinions (3,237 ha) and the Bay Delta Conservation Plan (26,305 ha). In the lower estuary, tidal marsh has proven its value to a wide array of species that live within it (Palaima 2012). In the Sacramento–San Joaquin Delta (Delta), one important function ascribed to restoration of freshwater tidal marshes is that they make large contributions to the food web of fish in open waters (BDCP 2013). The Ecosystem Restoration Program ascribed a suite of ecological functions to tidal marsh restoration, including habitat and food web benefits to native fish (CDFW 2010). This background was the basis for a symposium (Tidal Marshes and Native Fishes in the Delta: Will Restoration Make a Difference?) held at the University of California, Davis, on June 10, 2013. This paper summarizes conclusions the authors drew from the symposium.

The Sacramento-San Joaquin Delta: The Evolution and Implementation of Water Policy: An Historical Perspective

University of California, Davis (UC Davis) | June 1st, 1977

This report is a history of the attempts to control the encroachment of salinity from San Francisco Bay into the Delta of the Sacramento and San Joaquin rivers from 1920

This report is a history of the attempts to control the encroachment of salinity from San Francisco Bay into the Delta of the Sacramento and San Joaquin rivers from 1920 to the present. Two basic solutions to the problem present themselves: the physical separation of salt water from fresh water by means of a barrier at some point downstream from the Delta, or the release of sufficient water from upstream storage reservoirs to drive back tidal salinity.

The San Francisco Bay-Delta Agreement: Principles for Agreement on Bay-Delta Standards Between the State of California and the Federal Government

California State Water Resources Control Board (SWRCB) | December 15th, 1994

The San Francisco Bay-Delta: A failure of decision-making capacity

Environmental Science & Policy (Elsevier) | August 12th, 2009

The paper reviews the history of Bay-Delta decision-making in California in order to highlight the continuity between what happened with CALFED and what happened in the

The paper reviews the history of Bay-Delta decision-making in California in order to highlight the continuity between what happened with CALFED and what happened in the preceding decades since water project deliveries began in 1949. Throughout this period, there has been intense conflict about whether and how to transfer water from the Bay-Delta to users elsewhere—a conflict marked by a fundamental opposition of interests among stakeholders. We document how the State of California has failed to organize itself effectively to resolve this conflict and make a decision on how to manage the Delta. The strategy consistently adopted by the State was to encourage the main parties – agricultural and urban water diverters, and fisheries and other instream-protection interests – to work out a solution among themselves, rather than imposing one externally. However, economic theory suggests that a bargaining solution is unlikely to exist because of the extreme opposition of interest among the parties. The Bay-Delta history amply confirms this theoretical prediction. Thus, the State’s strategy of relying on voluntary agreement to resolve the issue is fundamentally misconceived and is, at some level, an abdication of its responsibility.

The Science of Non-native Species in a Dynamic Delta

Delta Stewardship Council (Delta Council) | May 21st, 2022

Invasion of non-native species is one of the greatest global threats to the integrity of ecosystems and one of the five main drivers of ecosystem change. When a new speci

Invasion of non-native species is one of the greatest global threats to the integrity of ecosystems and one of the five main drivers of ecosystem change. When a new species becomes part of the ecosystem, it can alter the food web, nutrient and contaminant cycling, abundances of other species, and habitat structure. The resultant changes in ecosystem services (e.g. water quality, water flow, fisheries, endangered species) and even ecosystem stability can impact a broad range of stakeholders and impinge on the responsibilities of many government agencies. The California San Francisco Bay-Delta ecosystem is one of the world’s most invaded estuaries. Indeed, non-native species comprise much of today’s Delta ecosystem. Non-native species threaten the Delta Plan’s coequal goals of “protecting, restoring, and enhancing the Delta ecosystem,“ and “providing a more reliable water supply for California” as well as state and federal objectives for preserving native species and ecosystems. The Delta Reform Act of 2009 recognized the importance of this issue and stipulated that the Delta Plan should restore a healthy ecosystem by promoting “self-sustaining, diverse populations of native and valued species by reducing the risk of take and harm from invasive species.” Reducing the impact of non-native species is also a core strategy highlighted in the Ecosystem Amendment to California’s Delta Plan.

The State Water Project Delivery Capability Report 2023 Addendum - Impacts of Subsidence

California Department of Water Resources (DWR) | May 7th, 2025

The purpose of this addendum is to show how ongoing subsidence effects on the California Aqueduct will impact operation of the State Water Project (SWP). The addendum pro

The purpose of this addendum is to show how ongoing subsidence effects on the California Aqueduct will impact operation of the State Water Project (SWP). The addendum provides information to SWP water users about a potential range of water delivery impacts over the next 20 years if no corrective action is taken to address the subsidence effects. However, the California Department of Water Resources (DWR) is committed to restore the conveyance capacity of the California Aqueduct and has an engineering plan for near-term fixes. DWR is also working with its partners to secure additional funding sources for this work. DWR is confident that the California Aqueduct capacity will be restored and the SWP will not see the impacts outlined in this addendum. Thus, long-term water supply planning activities by water users should rely on the potential future SWP allocation results presented in the 2023 Delivery Capability Report (DCR 2023) released in 2024.