San Joaquin River

Energy Down the Drain. The Hidden Costs of California's Water Supply

Natural Resources Defense Council (NRDC) | August 2nd, 2004

California has been through its share of scorching droughts and energy shortages, but many residents of the western United States may not realize the close con- n

California has been through its share of scorching droughts and energy shortages, but many residents of the western United States may not realize the close con- nections between water and power resources. Water utilities use large amounts of energy to treat and deliver water. Even after utilities deliver water, consumers burn more energy to heat, cool, and use the water. The California State Water Project is the largest single user of energy in California. In the process of delivering water from the San Francisco Bay-Delta to Southern California, the project uses 2 to 3 percent of all electricity consumed in the state. The State Water Project burns energy pumping water 2,000 feet over the Tehachapi Mountains—the highest lift of any water system in the world. The amount of energy used to deliver that water to residential customers in Southern California is equivalent to approximately one-third of the total average household electric use in the region. Ninety percent of all electricity used on farms is devoted to pumping groundwater for irrigation.

Enhancements to EcoAtlas’ CRAM analysis tools: Habitat Development Curves and Ecoregional Cumulative Distribution Function plots (CDFs)

San Francisco Estuary Institute (SFEI) | April 5th, 2016

Enhancing the Vision for Managing California’s Environmental Information

Delta Stewardship Council (Delta Council) | July 1st, 2015

The Environmental Data Summit, convened under the auspices of the Delta Stewardship Council’s Delta Science Program in June 2014, witnessed remarkable participation fro

The Environmental Data Summit, convened under the auspices of the Delta Stewardship Council’s Delta Science Program in June 2014, witnessed remarkable participation from experts across California, the nation, and even the world. Summit attendees from the public, private, federal, and non-profit sectors shared their views regarding the urgent needs and proposed solutions for California’s data-sharing and data-integration challenges, especially pertaining to the subject of environmental resource management in the era of “big data.” After all, this is a time when our data sources are growing in number, size, and complexity. Yet our ability to manage and analyze such data in service of effective decision-making lags far behind our demonstrated needs. In its review of the sustainability of water and environmental management in the California Bay-Delta, the National Research Council (NRC) found that “only a synthetic, integrated, analytical approach to understanding the effects of suites of environmental factors (stressors) on the ecosystem and its components is likely to provide important insights that can lead to enhancement of the Delta and its species” (National Research Council 2012). The present “silos of data” have resulted in separate and compartmentalized science, impeding our ability to make informed decisions. While resolving data integration challenges will not, by itself, produce better science or better natural resource outcomes, progress in this area will provide a strong foundation for decision-making. Various mandates ranging from the California Water Action Plan to the President’s executive order demanding federal open data policies demonstrate the consensus on the merits of modern data sharing at the scale and function needed to meet today’s challenges. This white paper emerges from the Summit as an instrument to help identify such opportunities to enhance California’s cross-jurisdictional data management. As a resource to policymakers, agency leadership, data managers, and others, this paper articulates some key challenges as well as proven solutions that, with careful and thoughtful coordination, can be implemented to overcome those obstacles. Primarily featured are tools that complement the State’s current investments in technology, recognizing that success depends upon broad and motivated participation from all levels of the public agency domain. This document describes examples, practices, and recommendations that focus on California’s Delta as an opportune example likely to yield meaningful initial results in the face of pressing challenges.  Once proven in the Delta, however, this paper’s recommended innovations would conceivably be applied statewide in subsequent phases.

Environmental Baseline Archeological and Historical Resources, Total Water Management Study for the Central Valley Basin, California

U.S. Bureau of Reclamation (USBR) | January 1st, 1975

Environmental Baseline Biological Resources - Fauna, Total Water Management Study for the Central Valley, California

U.S. Bureau of Reclamation (USBR) | January 1st, 1975

Environmental Characteristics of Select Managed Ponds in the Sacramento–San Joaquin Delta: Implications for Native Fish Conservation and Research

U.S. Geological Survey (USGS) | July 23rd, 2025

The use of wetlands to support native fish research and conservation efforts in the Sacramento–San Joaquin Delta (Delta) of California is a growing priority. The purpos

The use of wetlands to support native fish research and conservation efforts in the Sacramento–San Joaquin Delta (Delta) of California is a growing priority. The purpose of our study was to examine the physiochemical and biological characteristics of select managed ponds in the Delta to determine if they would be suitable habitats for research involving the conservation of delta smelt (Hypomesus transpacificus). We studied 10 managed ponds distributed across the central part of the Delta situated on Bacon Island and Bouldin Island in San Joaquin County, and Holland Tract and Webb Tract islands in Contra Costa County. The managed ponds had a diversity of physical habitat configurations and were not directly connected to waterways surrounding the islands and, therefore, not affected by tides. We studied the managed ponds from approximately November 2021 to December 2023 to assess water quality, zooplankton, fish, and pesticide metrics. Water levels in the managed ponds were managed to varying degrees and were mostly independent of climate-driven wet-dry seasonality. Water quality conditions varied among ponds and were independent of geographic location. Overall, mean monthly chlorophyll a concentration ranged from 15 to 57 (mean=30) micrograms per liter (μg/L), dissolved oxygen concentration ranged from 4 to 9 (mean=7) milligrams per liter (mg/L), pH was 8, salinity was 1 practical salinity units (PSU), specific conductance ranged from 1,202 to 1,839 (mean=1,471) microsiemens per centimeter (μS/cm), and turbidity ranged from 13 to 24 (mean=19) Formazin Nephelometric Units (FNU). Water temperature thresholds that contribute to stress (21 degrees Celsius [°C]) and mortality (28 °C) of delta smelt were often exceeded during summer and fall, though vertical stratification contributed to lower bottom temperatures in the deepest managed ponds, which could potentially provide thermal refugia for delta smelt so long as dissolved oxygen concentrations are suitable. Zooplankton populations were broadly similar among managed ponds and included calanoid and cyclopoid copepods that would be suitable prey for delta smelt. Overall average total zooplankton biomass, as measured with a Schindler-Patalas trap, was 0.6 μg/L (min=0, max=63.6) and peaked during spring at more than 4 μg/L. Fish populations highly varied among the managed ponds with potential predators of delta smelt such as largemouth bass (Micropterus salmoides) and black crappie (Pomoxis nigromaculatus) present in several of the managed ponds; predator distribution among ponds seemed to have been driven primarily by deliberate stocking to facilitate local fisheries. Measured pesticide concentrations were below U.S. Environmental Protection Agency Aquatic Life Benchmarks except for exceedances of three compounds (diuron [herbicide], clothianidin [insecticide], and deltamethrin [pyrethroid insecticide]) in samples collected from ponds on Bouldin Island and Webb Tract. Overall, most managed ponds seemed suitable to support delta smelt, though physical control of potential predators and summer temperature might be needed. The results provide guidance on how to engineer and manage new managed ponds to support research and conservation efforts for delta smelt and other native fishes.

Environmental Water Account: Need for Legislative Definition and Oversight

Legislative Analyst's Office (LAO) | January 29th, 2001

We recommend that the Legislature hold oversight hearings to evaluate CALFED's proposal for the Environmental Water Account, implemented to acquire water for endangered s

We recommend that the Legislature hold oversight hearings to evaluate CALFED's proposal for the Environmental Water Account, implemented to acquire water for endangered species protection and recovery in the Bay-Delta region. There are many policy and implementation issues that the Legislature should consider before CALFED proceeds with the new program, including the program's costs, benefits, impacts, governance, and funding. Funding should be governed by the "beneficiary pays" principle.

Ephemeral floodplain habitats provide best growth conditions for juvenile Chinook salmon in a California river

Environmental Biology of Fishes (Springer) | June 6th, 2008

We reared juvenile Chinook salmon for two consecutive flood seasons within various habitats of the Cosumnes River and its floodplain to compare fish growth in river and

We reared juvenile Chinook salmon for two consecutive flood seasons within various habitats of the Cosumnes River and its floodplain to compare fish growth in river and floodplain habitats. Fish were placed in enclosures during times when wild salmon would naturally be rearing in floodplain habitats. We found significant differences in growth rates between salmon reared in floodplain and river enclosures. Salmon reared in seasonally inundated habitats with annual terrestrial vegetation experienced higher growth rates than those reared in a perennial pond on the floodplain. Growth of fish in the non-tidal river upstream of the floodplain varied with flow in the river. When flows were high, there was little growth and high mortality, but when the flows were low and clear, the fish grew rapidly. Fish displayed very poor growth in tidally influenced river habitat below the floodplain, a habitat type to which juveniles are commonly displaced during high flow events due to a lack of channel complexity in the main-stem river. Overall, ephemeral floodplain habitats supported higher growth rates for juvenile Chinook salmon than more permanent habitats in either the floodplain or river. Variable responses in both growth and mortality, however, indicate the importance of providing habitat complexity for juvenile salmon in floodplain reaches of streams, so fish can find optimal places for rearing under different flow conditions.

Escalating Hydrological Extremes and Whiplashes in the Western U.S.: Challenges for Water Management and Frontline Communities

American Geophysical Union (AGU) | May 14th, 2025

Estimates of Natural and Unimpaired Flows for the Central Valley of California: Water Years 1922-2014 (draft)

California Department of Water Resources (DWR) | March 1st, 2016

Estimating regional water supplies that would have occurred absent human activities is a common practice in water resources planning. In this report, such theor

Estimating regional water supplies that would have occurred absent human activities is a common practice in water resources planning. In this report, such theoretical water supply estimates are referred to as “unimpaired” flow. Since 1980, the Department of Water Resources (Department) has periodically published estimates of Central Valley unimpaired flows. In spite of the Department’s previous attempts to distinguish between natural conditions and its calcula tion of theoretical unimpaired flows, unimpaired flow estimates have frequently been used as a surrogate measure of natural conditions, presumably because natural flow estimates were unavailable. A major objective of this report is to clarify the conceptua l differences between natural and unimpaired flows. In this report, the term “unimpaired” flow is used to describe a theoretically available water supply assuming existing river channel conditions in the absence of (1) storage regulation for water supply a nd hydropower purposes and (2) stream diversions for agricultural and municipal uses. Unimpaired flow estimates are theoretical in that such conditions have not occurred historically. In pristine watersheds which have undergone little land use change, unim paired flow estimates provide a fixed frame of reference to develop relationships between precipitation, runoff, and water supply based on long - term hydrologic records. For many years these relationships were based on the assumption of stationarity, i.e. that the past is a good indicator of the future. However, global warming now requires hydrologists and water resources managers to analyze non-stationary processes, requiring more sophisticated tools and techniques to quantify future water supplies. This report updates and extends the Department’s previous published estimates of unimpaired flows for 24 Central Valley sub-basins and the Delta. Monthly unimpaired flows are presented for water years 1922 - 2014.