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Aquapedia banner
Banner May 22, 2014

Your Online Water Encyclopedia

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Alphabetical List of Subjects

Overview February 11, 2014

Alphabetical List of Subjects

Water From A to Z

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A

Overview January 30, 2014

A

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Aquapedia background January 30, 2014 California Water Map Layperson's Guide to California Water

Acre-Foot

An acre-foot is a common way in the U.S. to measure water volume and use. It is the amount of water it takes to cover an acre of land one foot deep. An acre is about the size of a football field.

An acre-foot of water equals 325,851 gallons, and historically that was enough to serve the needs of two families for a year in California.

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Aquapedia background January 30, 2014

Agricultural Conservation

As the single largest water-consuming industry, agriculture has become a focal point for efforts to promote water conservation. In turn, discussions about agricultural water use often become polarized.

With this in mind, the drive for water use efficiency has become institutionalized in agriculture through numerous federal, state and local programs.

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Aquapedia background January 30, 2014

Agricultural Drainage

California’s rich agricultural productivity comes with a price. The dry climate that provides the almost year-round growing season also can require heavily irrigated soils. But such irrigation can degrade the local water quality.

Two of the state’s most productive farming areas in particular, the west side of the San Joaquin Valley and parts of the Imperial Valley in Southern California, have poorly drained and naturally saline soils.

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Aquapedia background January 30, 2014

Agricultural Drainage and the Sacramento-San Joaquin Delta

Few regions are as important to California water as the Sacramento-San Joaquin Delta, where the Sacramento and San Joaquin rivers converge to discharge into San Francisco Bay.

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Aquapedia background January 30, 2014

Agricultural Drainage Environmental Impacts

Agriculture drainage issues date back to the earliest farming. In ancient times, farmers let fields stay fallow hoping rain would flush out salt.

Today, salt and other contaminants continue to cause agricultural drainage problems, particularly in California. Whether a field is adequately drained, or saturated with water, the water still has to be removed.

The disposal of this often-contaminated water continues to be a challenge in California, with the environmental effects of selenium and other drainage-related elements changing the course of drainage planning.

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Aquapedia background September 8, 2016 California Water Map Layperson's Guide to California Water

Algal Blooms

Algal blooms are sudden overgrowths of algae. Their occurrence is increasing in California’s rivers, creeks and lakes and along the coast, threatening the lives of people, pets and fisheries.

Only a few types of algae can produce poisons, but even nontoxic blooms hurt the environment and local economies. When masses of algae die, the decaying can deplete oxygen in the water to the point of causing devastating fish kills.

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Aquapedia background August 25, 2016

All-American Canal

As one of the most productive agricultural regions in the world, the Imperial Valley receives its water from the Colorado River via the All-American Canal. Rainfall is scarce in the desert region at less than three inches per year and groundwater is of little value. 

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Aquapedia background August 25, 2016

Alluvium

Alluvium generally refers to the clay, silt, sand and gravel that are deposited by a stream, creek or other water body.  Alluvium is found around deltas and rivers, frequently making soils very fertile. Alternatively, “colluvium” refers to the accumulation at the base of hills, brought there from runoff (as opposed to a water body). The Oxnard Plain in Ventura County is a visible alluvial plain, where floodplains have drifted over time due to gradual deposits of alluvium, a feature also present in Red Rock Canyon State Park in Kern County.

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Aquapedia background August 25, 2016 California Water Map Layperson's Guide to the Central Valley Project

American River

North Fork American RiverThe American River originates high in the Sierra Nevada just west of Lake Tahoe, in the Tahoe and Eldorado national forests.

The birthplace of the California Gold Rush, the river today is a prime recreational destination and a major water supply source for the federal Central Valley Project.

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Aquapedia background January 30, 2014 Sacramento-San Joaquin Delta Map Layperson's Guide to California Water

Anadromous Fish

Chinook salmon returning to Battle CreekAnadromous fish are freshwater fish that migrate to sea and then return to spawn in fresh water.

In California, anadromous fish include coho salmon, chinook salmon and steelhead. Those inhabiting rivers across the Central Valley have experienced significant declines from historical populations. This is due to drought, habitat destruction, water diversions, migratory obstacles such as dams, unfavorable ocean conditions, pollution and introduced predator species.

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Aquapedia background January 30, 2014

Applied Water

Applied water refers to water delivered by an application to a user, either indoors or outdoors. Applied water use typically occurs in an agricultural or urban setting.

In agriculture, applied water is typically supplied through irrigation, which uses such devices as pipes and sprinklers. There are also different types of systems including gravity flow and pressurized systems.

With soil absorbing applied water and being porous (some water can move down below a plant’s root zone), it is necessary to apply more water than a crop might need.

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Aquapedia background January 30, 2014 California Water Map Layperson's Guide to Water Rights Law

Appropriative Rights

California law allows rivers, streams, lakes and other surface water to be diverted at one point and appropriated (used) beneficially at a separate point.

This “appropriative right” contrasts with a “riparian right,” which is based on ownership of property adjacent to surface water.

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Aquapedia background January 30, 2014

Aquifers

Aquifers are an unseen but critical resource in California’s water supply system.

These natural basins that sit below the surface are found underneath 40 percent of California’s land area.

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Aquapedia background January 30, 2014

Area-of-Origin and California Water

The legal term “area-of-origin” dates back to 1931 in California.

At that time, concerns over water transfers prompted enactment of four “area-of-origin” statutes. With water transfers from Yosemite’s Hetch Hetchy Valley to supply water for San Francisco and from Owens Valley to Los Angeles fresh in mind, the statutes were intended to protect local areas against export of water.

In particular, counties in Northern California had concerns about the state tapping their water to develop California’s supply.

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Aquapedia background December 29, 2016 Layperson's Guide to Flood Management

ARkStorm

Sacramento's K Street during the 1862 flood that inundated the Central Valley.ARkStorm stands for an atmospheric river (“AR”) that carries precipitation levels expected to occur once every 1,000 years (“k”). The concept was presented in a 2011 report by the U.S. Geological Survey (USGS) intended to elevate the visibility of the very real threats to human life, property and ecosystems posed by extreme storms on the West Coast.

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Aquapedia background September 7, 2016

Arsenic Contamination

Both the drought and high nitrate levels in shallow groundwater have necessitated deeper drilling of new wells in the San Joaquin Valley, only to expose water with heightened arsenic levels. Arsenic usually exists in water as arsenate or arsenite, the latter of which is more frequent in deep lake sediments or groundwater with little oxygen and is both more harmful and difficult to remove.

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Aquapedia background December 1, 2017 Layperson's Guide to Flood Management

Atmospheric Rivers

A massive 1986 Northern California flood near Marysville, north of Sacramento, caused the south levee of the Yuba River to breach, forcing thousands of residents to evacuate their homes.Atmospheric rivers are relatively narrow bands of moisture that ferry precipitation across the Pacific Ocean to the West Coast and are key to California’s water supply.

They are commonly referred to as the “Pineapple Express” because of their origins in tropical regions. While atmospheric rivers are necessary to keep California’s water reservoirs full, some of them are dangerous because the extreme rainfall and wind can cause catastrophic flooding and damage. Their presence has been likened to the West Coast version of the hurricane hazard posed to the southeastern United States.

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Aquapedia background January 30, 2014

Auburn Dam

Auburn Dam, also known as the Auburn-Folsom South Unit, is an unfinished federal Central Valley Project facility on the north fork of the American River above Folsom Dam.

Work on the dam was halted in 1977 following a magnitude 5.7 earthquake in 1975 near Oroville Dam, some 50 miles away, raising questions about the Auburn Dam’s safety. The dam remains unbuilt.

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Aquapedia background February 10, 2014

Jean Auer

Jean Auer (1937-2005) was the first woman to serve on the California State Water Resources Control Board and a pioneer for women aspiring to be leaders in the water world.

She is described as a “woman of great spirit who made large contributions to improve the waters of California.” She was appointed as the State Water Board’s public member by then-Governor Ronald Reagan and served from 1972-1977 during a time period that included the passage of the federal Clean Water Act. She became part of the growing movement for water quality regulations to stop water pollution.

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B

Overview January 30, 2014

B

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Aquapedia background February 11, 2014 Sacramento-San Joaquin Delta Map Layperson's Guide to the Delta

Bay Model

Operated by the U.S. Army Corps of Engineers, the Bay Model is a giant hydraulic replica of San Francisco Bay and the Sacramento-San Joaquin Delta. It is housed in a converted World II-era warehouse in Sausalito near San Francisco.

Hundreds of gallons of water are pumped through the three-dimensional, 1.5-acre model to simulate a tidal ebb and flow lasting 14 minutes.

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Aquapedia background February 4, 2014

Harvey O. Banks

Harvey O. Banks (1910-1996), a lifelong civil engineer, played an integral role in the development of water projects in California.

He became the first director of the state Department of Water Resources, appointed by Governor Goodwin J. Knight on July 5, 1956 — the date the department was officially established. He continued as director under Governor Edmund G. “Pat” Brown. During Banks’ tenure as director from 1956-1961, he was key in the planning and the initial construction of the California State Water Project (SWP).

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Aquapedia background January 30, 2014

Battle Creek

Battle Creek, a tributary of the Sacramento River in Shasta and Tehama counties, is considered one of the most important anadromous fish spawning streams in the Sacramento Valley.

At present, barriers make it difficult for anadromous fish, including chinook salmon and Central Valley steelhead trout, to migrate. Battle Creek has several hydroelectric dams, diversions and a complex canal system between its north and south forks that impede migration.

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Aquapedia background January 30, 2014

Bay Delta Conservation Plan

The Bay Delta Conservation Plan is a permitting process for long-term project permits for the Sacramento-San Joaquin Delta that centers on co-equal goals of species conservation and improving water supplies and delivery.

The BDCP aims to separate its water delivery system from Delta freshwater flows and restore thousands of acres of habitat, restore river flows to more natural patterns and address issues affecting the health of fish populations.

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Aquapedia background September 7, 2016

Biochemical Oxygen Demand

The biochemical oxygen demand (BOD) of water determines the impact of decaying matter on species in a specific ecosystem. Sampling for BOD tests how much oxygen is needed by bacteria to break down the organic matter.

  • Read about the details of testing BOD
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Aquapedia background August 15, 2016

Bioconcentration

Process by which an individual organism directly concentrates a substance from the surrounding water.

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Aquapedia background August 15, 2016

Biomagnification

Process by which a substance is passed up the food chain resulting in an especially high level of the substance at upper levels of the food chain.

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Aquapedia background May 4, 2021

Carl Boronkay

Carl Boronkay (1929-2017) was general manager of the Metropolitan Water District of Southern California (MWD) between 1984 and 1993. Boronkay is credited with developing a long-term vision for the district’s sustainable water supplies as well as large projects such as Diamond Valley Lake, the large reservoir near the Riverside County town of Hemet, and the Inland Feeder that connects the State Water Project to the Colorado River Aqueduct and Diamond Valley Lake.

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Aquapedia background October 3, 2014

Ralph M. Brody

Ralph M. Brody (1912-1981) served as Gov. Pat Brown’s special counsel on water issues and chief deputy director of the Department of Water Resources.

He was instrumental in ensuring passage of the State Water Project in 1960. He chaired the California Water Commission from 1960 -1966. From 1960 until his retirement in 1977, he was manager and chief counsel for Westlands Water District.

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Aquapedia background February 3, 2014

Edmund G. “Pat” Brown

Edmund G. “Pat” Brown (1905-1996) was California’s governor from 1959-1967, exemplified the best in public service and left a wide-ranging legacy that featured first and foremost the State Water Project (SWP) and California Aqueduct but also included the Fair Housing Act, the Fair Employment Act, the Master Plan for Higher Education and highway expansion.

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Aquapedia background September 1, 2016 California Water Map

Butte Creek

Butte Creek, a tributary of the Sacramento River, begins less than 50 miles northeast of Chico, California and is named after nearby volcanic plateaus or “buttes.” The cold, clear waters of the 93-mile creek sustain the largest naturally spawning wild population of spring-run chinook salmon in the Central Valley. Several other native fish species are found in Butte Creek, including Pacific lamprey and Sacramento pikeminnow.

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C

Overview January 30, 2014

C

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Aquapedia background January 30, 2014

CALFED

CALFED began as a cooperative state-federal planning effort between water, environmental, state and federal officials involved in the 1994 Bay-Delta Accord.

That accord aimed to protect the Sacramento-San Joaquin Delta and provide water to urban and agricultural interests.

Today, as part of the Delta Reform Act of 2009, the Delta Stewardship Council has in effect taken on the CALFED mission.

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Aquapedia background January 30, 2014 California Water Map Layperson's Guide to the State Water Project

California Aqueduct

The California Aqueduct, a critical part of the State Water Project, carries water from the Sacramento-San Joaquin Delta to the San Joaquin Valley and Southern California.

Established as part of a $1.75 billion bond passed by voters in 1960, the 444-mile-long California Aqueduct (formally known as the Edmund G. Brown California Aqueduct) begins at the Harvey O. Banks Pumping Plant in the Delta. It parallels Interstate 5 south to the Tehachapi Mountains.

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Aquapedia background January 30, 2014

California Endangered Species Act

California was the first state in the nation to protect fish, flora and fauna with the enactment of the California Endangered Species Act in 1970. (Congress followed suit in 1973 by passing the federal Endangered Species Act. See also the Convention on International Trade in Endangered Species of Wild Fauna and Flora, or CITES.)

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Aquapedia background January 30, 2014 California Water Map Layperson's Guide to California Water

California Environmental Quality Act

The California Environmental Quality Act, commonly known as CEQA, is foundational to the state’s environmental protection efforts. The law requires proposed developments with the potential for “significant” impacts on the physical environment to undergo an environmental review. 

Since its passage in 1970, CEQA (based on the National Environmental Policy Act) has served as a model for similar legislation in other states.

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Aquapedia background January 30, 2014

California Gold Rush and Today’s Water

More than 100 years ago, California’s Gold Rush left a toxic legacy that continues to cause problems in Northern California watersheds.

The discovery of gold in John Sutter’s millrace at Coloma in the 1840s drew people from around the globe.

Over the course of decades, intense efforts were focused on washing and prying gold from the hills of the Sierra Nevada.

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Aquapedia background January 30, 2014 Layperson's Guide to California Water California Water Map Water & the Shaping of California

California Water Overview

Aerial view of the Sacramento-San Joaquin DeltaCalifornia will always be inextricably linked to its water resources. Water continues to shape the state’s development and no resource is as vital to California’s urban centers, farms, industry, recreation, scenic beauty and environmental preservation.

But California’s relationship to water is also one that continues to generate controversy.

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Aquapedia background January 30, 2014 California Water Map Layperson's Guide to California Water

California Water Plan

Every five years the California Department of Water Resources updates its strategic plan for managing the state’s water resources, as required by state law.

The California Water Plan, or Bulletin 160, projects the status and trends of the state’s water supplies and demands under a range of future scenarios.

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Aquapedia background January 30, 2014

California Water Timeline

1769 First permanent Spanish settlements established. Water rights established by Spanish law.

1848 Gold discovered on the American River. Treaty of Guadalupe signed, California ceded from Mexico, California republic established.

1850 California admitted to Union. Construction begins on Delta levees and channels.

1860 Legislature authorizes the formation of levee and reclamation districts.

1862  Major flood in Sacramento Valley inundates new city.

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Aquapedia background January 30, 2014

California Wild and Scenic Rivers Act

North Fork of the American River,  a section deemed wild and scenic. California’s Legislature passed the Wild and Scenic Rivers Act in 1972, following the passage of the federal Wild and Scenic Rivers Act by Congress in 1968. Under California law, “[c]ertain rivers which possess extraordinary scenic, recreational, fishery, or wildlife values shall be preserved in their free-flowing state, together with their immediate environments, for the benefit and enjoyment of the people of the state.”

Rivers are classified as:

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Aquapedia background February 14, 2014

Francis C. Carr

Francis C. CarrFrancis C. Carr (1875-1944) and his descendants played a prominent role in the development of the federal Central Valley Project, including Shasta Dam, and the creation of the Whiskeytown National Recreation Area.

In the Northern California community of Redding, he was a justice of peace, a renowned water rights attorney in the law firm of Carr and Kennedy and helped form the Anderson-Cottonwood Irrigation District. He was often in the nation’s Capitol in Washington, D.C., advocating for funds from Congress to get this visionary project built for the benefit of all of California. In his honor, the Judge Francis Carr Powerplant was named after him.

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Aquapedia background January 30, 2014

Carson River and the Newlands Project

The Carson River begins in the Sierra Nevada southeast of Lake Tahoe as two separate forks.

The East Fork begins in the mountains of California’s Sonora Pass and after flowing through California and Nevada, it meets the West Fork just south of Carson City. The West Fork forms at California’s Carson Pass, running through California and into Nevada to its junction with the East Fork.

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Aquapedia background February 11, 2014

Rachel Carson

Rachel Carson (1907-1964) authored Silent Spring, a book published in 1962 about the impacts of pesticides on the ecosystem and credited with beginning the modern environmental movement.

Before becoming a full-time writer, she worked at the U.S. Bureau of Fisheries, renamed the Fish and Wildlife Service, from 1935-1952 as a biologist and then editor-in-chief of publications.

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Aquapedia background January 30, 2014 Layperson's Guide to the Central Valley Project

Central Valley Project

Birthed in part by a long-ago federal effort to create farmland, the Central Valley Project today is one of the largest water storage and transport systems in the world. In years of normal precipitation, it stores and distributes about 20 percent of the state’s developed water through its massive system of reservoirs and canals.

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Aquapedia background January 30, 2014 Layperson's Guide to the Central Valley Project

Central Valley Project Improvement Act

The Central Valley Project Improvement Act supports a major federal effort to store and transport water in California’s Central Valley.

The 1992 Act changed operations of Central Valley Project; a major project that addresses flooding, storage and irrigation issues in the valley [see also Central Valley Project].

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Aquapedia background January 30, 2014

Central Valley Wetlands and Riparian Habitat

In the Central Valley, wetlands—partly or seasonally saturated land that supports aquatic life and distinct ecosystems— provide critical habitat for a variety of wildlife.

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Aquapedia background February 10, 2014

Ira J. “Jack” Chrisman

Ira J. “Jack” Chrisman (1910-1988) became a well-known force in California’s water history beginning back in 1955 after his family home was flooded in the San Joaquin Valley town of Visalia.

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Aquapedia background January 30, 2014

Clifton Court Forebay and Banks Pumping Plant

The Clifton Court Forebay is a key part of the State Water Project (SWP) and serves as ground zero for the starting point of the California Aqueduct (which delivers water to Southern California). Clifton Court also recharges water in the San Joaquin Valley via the Delta-Mendota Canal.

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Aquapedia background January 30, 2014 Layperson's Guide to Climate Change and Water Resources California Water Map Colorado River Basin Map

Climate Change

Climate change involves natural and man-made changes to weather patterns that occur over millions of years or over multiple decades.

In the past 150 years, human industrial activity has accelerated the rate of change in the climate due to the increase in greenhouse gases (carbon dioxide, methane and nitrous oxide, among others). Scientific studies describing this climate change continue to be produced and its expected impacts continue to be assessed.

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Aquapedia background January 30, 2014

Coachella Valley

The Coachella Valley in Southern California’s Inland Empire is one of several valleys throughout the state with a water district established to support agriculture.

Like the others, the Coachella Valley Water District in Riverside County delivers water to arid agricultural lands and constructs, operates and maintains a regional agricultural drainage system. These systems collect drainage water from individual farm drain outlets and convey the water to a point of reuse, disposal or dilution.

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Aquapedia background August 15, 2016

Cogeneration

Process by which energy is extracted from the waste heat of an industrial process such as a steam boiler or food processing system.

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Aquapedia background September 7, 2016

Coliform Bacteria

Coliform Bacteria as Indices

Directly detecting harmful pathogens in water can be expensive, unreliable and incredibly complicated. Fortunately, certain organisms are known to consistently coexist with these harmful microbes which are substantially easier to detect and culture: coliform bacteria. These generally non-toxic organisms are frequently used as “indicator species,” or organisms whose presence demonstrates a particular feature of its surrounding environment.

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Aquapedia background February 3, 2014

Gordon Cologne

Gordon Cologne served for 10 years in the California Legislature during the 1960s and early 1970s while the California State Water Project was being built.

His interest in water issues began from his early life in the Coachella Valley desert. An attorney, he worked in both the public sector in Washington, D.C, and then in private practice in California. He also served his local community as a member of the city of Indio City Council, including as mayor, before his decision to run for election to fill an open seat in the Assembly.

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Aquapedia background January 30, 2014 Colorado River Basin Map Layperson's Guide to the Colorado River Basin Layperson's Guide to the Colorado River Delta

Colorado River

Colorado RiverThe turbulent Colorado River is one of the most heavily regulated and hardest working rivers in the world.

Geography

The Colorado falls some 10,000 feet on its way from the Rocky Mountains to the Gulf of California, helping to sustain a range of habitats and ecosystems as it weaves through mountains and deserts.

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  • Colorado River Timeline
Aquapedia background August 25, 2016 Colorado River Basin Map

Colorado River Aqueduct

The Colorado River Aqueduct, built by the Metropolitan Water District  of Southern California, cuts through the California desert.The Colorado River Aqueduct, a 242-mile-long channel completed in 1941 by the Metropolitan Water District of Southern California, carries water from the Colorado River to urban Southern California. The aqueduct is one of three conveyance systems of imported water to Southern California, the other two being the California Aqueduct and the Los Angeles Aqueduct.

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Aquapedia background September 4, 2020 Colorado River Basin Map

Colorado River Compact

Signing of the Colorado River Compact in 1922The Colorado River Compact of 1922 marked the first time in U.S. history that more than three states negotiated an agreement among themselves to apportion the waters of a stream or river.

The compact is the cornerstone of the “Law of the River” – a complex set of interstate compacts, federal laws, court decisions and decrees, contracts and federal actions that regulate use of the Colorado River.

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Aquapedia background February 11, 2014

Colorado River Delta (in Mexico)

The Colorado River Delta is located at the natural terminus of the Colorado River at the Gulf of California, just south of the U.S.-Mexico border. The desert ecosystem was formed by silt flushed downstream from the Colorado and fresh and brackish water mixing at the Gulf.

The Colorado River Delta once covered 9,650 square miles but has shrunk to less than 1 percent of its original size due to human-made water diversions.

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Aquapedia background January 30, 2014

Colorado River 2007 Interim Guidelines And Drought Contingency Plans

In 2005, after six years of severe drought in the Colorado River Basin, federal officials and representatives of the seven basin states — California, Arizona, Nevada, New Mexico, Colorado, Utah and Wyoming — began building a framework to better respond to drought conditions and coordinate the operations of the basin’s two key reservoirs, Lake Powell and Lake Mead.

The resulting Interim Guidelines for Lower Basin Shortages and the Coordinated Operations for Lake Powell and Lake Mead (Interim Guidelines) identified the conditions for shortage determinations and details of coordinated reservoir operations. The 2007 Interim Guidelines remain in effect through Dec. 31, 2025.

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Aquapedia background February 11, 2014 Layperson's Guide to the Colorado River Basin Colorado River Basin Map

Lower Colorado River Multispecies Conservation Program

In 2005, the Interior Department launched a program to recover 27 species in the lower Colorado River, including seven the federal government has deemed threatened or endangered or threatened with extinction. The species include fish, birds, bats, mammals, insects, amphibians, reptiles, rodents and plants

The Lower Colorado River Multispecies Conservation Program has a 50-year plan to create at least 8,132 acres of new habitat and restore habitat that has become degraded.

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Colorado River Timeline

600 Ancestral Pueblo and Hohokam Indians develop water distribution systems.

1500 Spanish explorers introduce livestock and ditch systems called acequias.

1847 Mormons arrive in the Salt Lake Valley; begin cultivating farmland.

1859 Oliver Wozencraft promotes idea of irrigating the Imperial Valley.

1865 Lower Colorado River lands begin to be set aside for American Indians.

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Aquapedia background February 11, 2014

Colorado River Water and Mexico

The Mexican Water Treaty of 1944 committed the U.S. to deliver 1.5 million acre-feet of water to Mexico on an annual basis, plus an additional 200,000 acre-feet under surplus conditions. The treaty is overseen by the International Boundary and Water Commission.

Colorado River water is delivered to Mexico at Morelos Dam, located 1.1 miles downstream from where the California-Baja California land boundary intersects the river between the town of Los Algodones in northwestern Mexico and Yuma County, Ariz.

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Colorado River Water Use 4.4 Plan

California’s Colorado River Water Use Plan (known colloquially as the 4.4 Plan) intends to wean the state from its reliance on the surplus flows from the river and return California to its annual 4.4 million acre-feet basic apportionment of the river.

In the past, California has also used more than its basic apportionment.  Consequently, the U.S. Department of Interior urged California to devise a plan to reduce its water consumption to its basic entitlement.

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Conjunctive Use

Conjunctive use is a catch-phrase for coordinated use of surface water and groundwater— literally going with the flow to maximize sufficient yield.

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Consumptive Water Use

Diversions of water withdrawn upstream and not returned downstream as waste water.

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Contaminants

Contaminants exist in water supplies from both natural and manmade sources. Even those chemicals present without human intervention can be mobilized from introduction of certain pollutants from both point and nonpoint sources.  

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Contra Costa Canal

Construction began in 1937 to build the Contra Costa Canal, the first part of the federal Central Valley Project.  The Contra Costa Canal runs from the Sacramento-San Joaquin Delta, where it draws its water near Knightsen, to the eastern and central parts of Contra Costa County. It is about 30 miles from San Francisco.

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Conveyance

Infrastructure providing for the movement of water. 

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C.W. Bill Jones Pumping Plant

The C.W. Bill Jones Pumping Plant (formerly known as the Tracy Pumping Plant) sits at the head of the 117-mile long Delta-Mendota Canal.

Completed in 1951, the canal begins near Tracy, Calif. and follows the Coast Range south, providing irrigation water to the west side of the San Joaquin Valley along its route and terminating at Mendota Pool.

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Overview February 3, 2014

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Aquapedia background February 3, 2014 Layperson's Guide to the Central Valley Project Layperson's Guide to the State Water Project Oroville Dam Shasta Dam Hoover Dam

Dams

Dams have allowed Californians and others across the West to harness and control water dating back to pre-European settlement days when Native Americans had erected simple dams for catching salmon.

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Aquapedia background May 4, 2021 Lake Tahoe State Water Project Oroville Dam Lake Perris

Pauline Davis

Pauline DavisPauline Davis (1917-1995), who represented all or portions of 12 rural Northern California counties in the California Assembly, guided some of the state’s most significant water development proposals through the Legislature.

During her legislative career from 1952 to 1976, Davis concentrated on water issues important to her constituents by championing area-of-origin protections for water targeted for export as part of the fledgling State Water Project.

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Aquapedia background February 3, 2014

Delta-Mendota Canal

The117-mile long Delta-Mendota Canal in central California delivers water from the Sacramento-San Joaquin Delta to the San Joaquin Valley. It is part of the Central Valley Project.

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Delta Plan

The Delta Plan is a comprehensive management plan for the Sacramento San Joaquin Delta intended to help the state meet the coequal goals of water reliability and ecosystem restoration.

The Delta Stewardship Council, which oversees the Delta Plan, adopted a final version in May 2013 after three years of study and public meetings. Once completed, the Bay Delta Conservation Plan could be incorporated into the Delta Plan.

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Delta Pumping Plant Fish Protection Agreement

The Delta Pumping Plant Fish Protection Agreement stems from an early effort to balance the needs of fish protection and State Water Project operations.  Negotiated in the mid-1980s, the agreement foreshadowed future battles over fish protection and pumping. [See also Sacramento-San Joaquin Delta.]

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Delta Risk Management Strategy

Overseen by the California Department of Water Resources, California Department of Fish and Wildlife and the U.S. Army Corps of Engineers, the Delta Risk Management Strategy evaluated the sustainability of the Sacramento-San Joaquin Delta and assessed major risks from floods, seepage, subsidence and earthquakes, sea level rise and climate change.

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Aquapedia background February 3, 2014 Sacramento-San Joaquin Delta Map Layperson's Guide to the Delta

Delta Smelt

The endangered Delta smelt is a 3-inch fish found only in the Sacramento-San Joaquin Delta. It is considered especially sensitive because it lives just one year, has a limited diet and exists primarily in brackish waters (a mix of river-fed fresh and salty ocean water that is typically found in coastal estuaries).

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Delta Stewardship Council

The Delta Stewardship Council was created as an independent state agency in 2009 to achieve California’s coequal goals for the Sacramento-San Joaquin Delta of providing a more reliable water supply for the state and protecting, restoring and enhancing the Delta ecosystem. 

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Desalination

Recurrent droughts and uncertainties about future water supplies have led several California communities to look to treat salty water for supplemental supplies through a process known as desalination.

Desalination removes salt and other dissolved minerals from water and is one method to reclaim water for other uses. This can occur with ocean water along the coast and in the interior at spots that draw from ancient salt water deep under the surface or where groundwater has been tainted by too much salt.

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Developed Water

Developed water is water that is controlled and managed for a variety of uses. These uses include water stored in dams and reservoirs, or pumped, diverted or channeled in aqueducts.

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Diamond Valley Lake

With a holding capacity of more than 260 billion gallons, Diamond Valley Lake is Southern California’s largest reservoir. It sits about 90 miles southeast of Los Angeles and just west of Hemet in Riverside County where it was built in 2000. The offstream reservoir was created by three large dams that connect the surrounding hills, costing around $1.9 billion and doubling the region’s water storage capacity.

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Aquapedia background February 10, 2014

Joan Didion

Joan Didion (1934-2021) was a native California author and playwright whose famous writings have featured California water issues.

Born and reared in Sacramento, she wrote extensively and personally about her feelings on the subject of water. In her memoir, Where I Was From, she told not only the story about her pioneering family’s roots in the Sacramento area but also of the seasonal flooding, the water politics and controversies, and the California State Water Project (SWP) and federal Central Valley Project (CVP).

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Aquapedia background October 1, 2018 Solving Water Challenges in Disadvantaged Communities

Disadvantaged Communities

Disadvantaged communities are those carrying the greatest economic, health and environmental burdens. They include poverty, high unemployment, higher risk of asthma and heart disease, and often limited access to clean, affordable drinking water.

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Aquapedia background February 3, 2014 All Things Drought California Water Map Layperson's Guide to Water Conservation Water Conservation Tips Up Close and Personal: Water Use at Home Drought FAQs

Drought

Drought—an extended period of limited or no precipitation—is a fact of life in California and the West, with water resources following boom-and-bust patterns. During California’s 2012–2016 drought, much of the state experienced severe drought conditions: significantly less precipitation and snowpack, reduced streamflow and higher temperatures. Those same conditions reappeared early in 2021 prompting Gov. Gavin Newsom in May to declare drought emergencies in watersheds across 41 counties in California.

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Overview February 3, 2014

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Aquapedia background February 3, 2014

East Branch Aqueduct

One of two State Water Project aqueducts serving Southern California, the East Branch Aqueduct stores water in Silverwood Lake and Lake Perris.

After being pumped over the Tehachapi Mountains from the Edmonston Pumping Plant, water for the East Branch Aqueduct passes through Palmdale and Lancaster [see also West Branch Aqueduct]. The water is then stored for distribution to Inland Empire cities such as San Bernardino and Riverside.

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Aquapedia background January 30, 2014

Arthur D. Edmonston

Arthur D. Edmonston directed the early planning of the Central Valley Project, State Water Project and State Water Plan.

He served as California state engineer and chief of the Division of Water Resources (predecessor to the Department of Water Resources) from 1950-1955, a time of rapid population, agricultural and industry growth California. Water shortages were common, and groundwater supplies were being overdrafted.

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A.D. Edmonston Pumping Plant

The world’s largest water lift, the Edmonston Pumping Plant is a State Water Project facility. The pumping plant plays a vital role in Southern California’s economy by supplying the semi-arid region with badly needed water.

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Aquapedia background September 1, 2016 California Water Map Layperson's Guide to California Water

Eel River

The Eel River supports one of California’s largest wild salmon and steelhead runs in a watershed that hosts the world’s largest surviving stands of ancient redwoods.

The Eel flows generally northward from Northern California’s Mendocino National Forest to the Pacific, a few miles south of Eureka. The river and its tributaries drain more than 3,500 square miles, the state’s third-largest watershed.

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Aquapedia background September 10, 2014 Water Cycle Poster Layperson's Guide to Flood Management

El Niño/La Niña

California’s seasonal weather is influenced by El Niño and La Niña – temporary climatic conditions that, depending on their severity, make the weather wetter or drier than normal.

El Niño and La Niña episodes typically last 9 to 12 months, but some may last for years. While their frequency can be quite irregular, El Niño and La Niña events occur on average every two to seven years. Typically, El Niño occurs more frequently than La Niña, according to the National Oceanic and Atmospheric Administration (NOAA).

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Entrainment

Fish or fish larvae sucked into pumps or water diversions.

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Aquapedia background February 3, 2014

Environmental Issues and Water

Environmental concerns have closely followed California’s development of water resources since its earliest days as a state.

Early miners harnessed water to dislodge gold through hydraulic mining. Debris resulting from these mining practices washed down in rivers and streams, choking them and harming aquatic life and causing flooding.

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Aquapedia background August 7, 2017 Layperson's Guide to the Delta

Estuary

Suisun Marsh, part of the San Francisco Bay-Delta estuary, is the largest contiguous brackish water marsh on the West Coast of North America.Estuaries are places where fresh and salt water mix, usually at the point where a river enters the ocean. They are the meeting point between riverine environments and the sea, with a combination of tides, waves, salinity, fresh water flow and sediment. The constant churning means there are elevated levels of nutrients, making estuaries highly productive natural habitats.

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Evaporation Ponds

Evaporation ponds contain agricultural drainage water and are used when agricultural growers do not have access to rivers for drainage disposal.

Drainage water is the only source of water in many of these ponds, resulting in extremely high concentrations of salts. Concentrations of other trace elements such as selenium are also elevated in evaporation basins, with a wide degree of variability among basins.

Such ponds resemble wetland areas that birds use for nesting and feeding grounds and may pose risks to waterfowl and shorebirds.

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Overview February 3, 2014

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Aquapedia background February 3, 2014 California Water Map Layperson's Guide to California Water

Federal Endangered Species Act

The federal government passed the Endangered Species Act in 1973, following earlier legislation. The first, the  Endangered Species Preservation Act of 1966, authorized land acquisition to conserve select species. The Endangered Species Conservation Act of 1969 then expanded on the 1966 act, and authorized “the compilation of a list of animals “threatened with worldwide extinction” and prohibits their importation without a permit.”

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Federal Reserved Rights

Federal reserved rights were created when the United States reserved land from the public domain for uses such as Indian reservations, military bases and national parks, forests and monuments.  [See also Pueblo Rights].

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Aquapedia background February 14, 2014

Flood Forecasting

Flood forecasting allows flood control managers to predict, with a high degree of accuracy, when local flooding is likely to take place.

Forecasts typically use storm runoff data, reservoir levels and releases to predict the rise in river levels.

In Northern California the National Weather Service, in cooperation with the state’s California-Nevada River Forecast Center in Sacramento, forecasts flooding.

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Aquapedia background February 14, 2014 Layperson's Guide to Flood Management Layperson's Guide to Climate Change and Water Resources California Water Map

Flooding and Flood Management

Image shows floodwaters from a series of atmospheric rivers that caused a road closure at Highway 20 near Williams in Colusa County in January 2023. When people think of natural disasters in California, they typically think about earthquakes. Yet the natural disaster that residents are most likely to face involves flooding, not fault lines. In fact, all 58 counties in the state have declared a state of emergency from flooding at least three times since 1950. And the state’s capital, Sacramento, is considered one of the nation’s most flood-prone cities. Floods also affect every Californian because flood management projects and damages are paid with public funds.

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Aquapedia background February 14, 2014 California Water Map Layperson's Guide to Flood Management California Spent Decades Trying to Keep Central Valley Floods at Bay. Now It Looks to Welcome Them Back

Floodplains in California

With the dual threats of aging levees and anticipated rising sea levels, floodplains — low areas along waterways that flood during wet years — are increasingly at the forefront of many public policy and water issues in California.

Adding to the challenges, many floodplains have been heavily developed and are home to major cities such as Sacramento. Large parts of California’s valleys are historic floodplains as well.

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Aquapedia background February 14, 2014

Fracking

Hydraulic fracturing, commonly known as fracking, injects high pressure volumes of water, sand and chemicals into existing wells to unlock natural gas and oil. The technique essentially fractures the rock to get to the otherwise unreachable deposits.

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Aquapedia background September 8, 2016

Freshwater

The United States Geographical Survey (USGS) defines freshwater as containing less than 1,000 milligrams per liter dissolved solids. However, 500 milligrams per liter is usually the cutoff for municipal and commercial use. Most of the Earth’s water is saline, 97.5 percent with only 2.5 percent fresh.

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Aquapedia background February 14, 2014 Layperson's Guide to the Central Valley Project California Water Map

Friant Dam

Friant DamFriant Dam, located just north of Fresno, is a part of the federal Central Valley Project and captures the upper San Joaquin River’s flow in Millerton Lake. The 319-foot high concrete gravity dam diverts water into the 152-mile Friant-Kern Canal, which delivers water south to Bakersfield, and the Madera Canal, which runs 36 miles to the north.

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Aquapedia background February 14, 2014 California Water Map Layperson's Guide to the Central Valley Project

Friant-Kern Canal

Friant-Kern CanalA part of the federal Central Valley Project (CVP), the 152-mile Friant-Kern Canal in California’s San Joaquin Valley plays a critical role in delivering water to 1 million acres of farmland and 250,000 people from the Fresno area south to Bakersfield.

The Friant-Kern Canal was designed as a gravity-fed facility and does not rely on pumps to move water. It is part of the CVP’s Friant Division Project that stores water from the San Joaquin River in Millerton Lake behind Friant Dam, 10 miles northeast of Fresno. The Madera Canal takes some of that water north to Chowchilla.

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Overview February 3, 2014

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Aquapedia background February 3, 2014

David A. Gaines

David A. Gaines (1947-1988) is known for founding the Mono Lake Committee in 1978 with the goal of preserving its ecosystem and leading a grassroots effort to “Save Mono Lake.” The result would be an environmental cause célèbre. As a synopsis of the Mono Lake litigation, in 1979 a lawsuit was filed against the Los Angeles Department of Water and Power (DWP) to stop diversions to Southern California — citing the public trust values at Mono Lake.

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Aquapedia background February 11, 2014 Interested in applying for the next California or Colorado River Water Leader cohorts? IN MEMORIAM: William R. Gianelli

William R. “Bill” Gianelli

William R. “Bill” Gianelli (1919-2020) was a civil engineer who served not only as director of the California Department of Water Resources (DWR) from 1967-1973 during Gov. Ronald Reagan’s administration, but worked as a civil servant under Govs. Earl Warren, Goodwin Knight and Edmund G. “Pat” Brown during all phases of the California State Water Project (SWP): its design, planning and construction.

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Aquapedia background February 11, 2014

Thomas J. “Tom” Graff

Thomas J. “Tom” Graff (1944-2009) opened up the California office of the Environmental Defense Fund in 1971 and was its regional director for more than 35 years.

Throughout his life, he was committed to the environment and the mentorship of environmental leaders. He was revered as an influential environmental lawyer on the state and federal water circuits and public forums and used strategic acumen to build partnerships to solve water problems with long-lasting solutions.

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Aquapedia background February 3, 2014 Layperson's Guide to California Water

Grey Water

Grey water, also spelled as gray water, is water that already has been used domestically, commercially and industrially. This includes the leftover, untreated water generated from washing machines, bathtubs and bathroom sinks.

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Aquapedia background February 3, 2014 California Groundwater Map Layperson's Guide to Groundwater

Groundwater

If California were flat, its groundwater would be enough to flood the entire state 8 feet deep. The enormous cache of underground water helped the state become the nation’s top agricultural producer. Groundwater also provides a critical hedge against drought to sustain California’s overall water supply.

In years of average precipitation, about 40 percent of the state’s water supply comes from underground. During a drought, the amount can approach 60 percent.

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Groundwater Adjudication

When multiple parties withdraw water from the same aquifer, groundwater pumpers can ask the court to adjudicate, or hear arguments for and against, to better define the rights that various entities have to use groundwater resources. This is known as  groundwater adjudication. [See also California water rights and Groundwater Law.]

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Aquapedia background February 3, 2014

Groundwater Banking

Groundwater banking is a process of diverting floodwaters or other surface water into an aquifer where it can be stored until it is needed later. In a twist of fate, the space made available by emptying some aquifers opened the door for the banking activities used so extensively today.

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Groundwater Basin

Aquifer or system of aquifers that has reasonably well-defined boundaries.

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Groundwater Law

California, like most arid Western states, has a complex system of surface water rights that accounts for nearly all of the water in rivers and streams.

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Groundwater Legislation

California has considered, but not implemented, a comprehensive groundwater strategy many times over the last century.

One hundred years ago, the California Conservation Commission considered adding  groundwater regulation into the Water Commission Act of 1913.  After hearings were held, it was decided to leave groundwater rights out of the Water Code.

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Aquapedia background February 4, 2014 California Groundwater Map Layperson's Guide to Groundwater Sustainable Groundwater Management Act (SGMA)

Groundwater Management

Groundwater pump in California's Central ValleyGroundwater management is recognized as critical to supporting the long-term viability of California’s aquifers and protecting the nearby surface waters that are connected to groundwater.

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Aquapedia background February 11, 2014 California Groundwater Map Layperson's Guide to Groundwater

Groundwater Pollutants

The natural quality of groundwater in California depends on the surrounding geology and on the source of water that recharges the aquifer.

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Aquapedia background July 20, 2017 California Groundwater Map Layperson's Guide to Groundwater

Groundwater Replenishment

Groundwater replenishment happens through direct recharge and in-lieu recharge. Water used for direct recharge most often comes from flood flows, water conservation, recycled water, desalination and water transfers.

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Groundwater Treatment

The treatment of groundwater— the primary source of drinking water and irrigation water in many parts of the United States — varies from community to community, and even from well to well within a city depending on what contaminants the water contains.

In California, one-half of the state’s population drinks water drawn from underground sources [the remainder is provided by surface water].

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Overview February 4, 2014

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Aquapedia background February 11, 2014

Robert “Bob” M. Hagan

Robert “Bob” M. Hagan, Ph.D. (1917-2002), internationally renowned for his expertise in the relationships between plants, water, soil and water use efficiency — specifically in the area of agricultural water use — was a professor of water science, an irrigationist in the California Agricultural Experiment Station and a statewide extension specialist in the California Agricultural Extension Service during a 50-year career with the University of California, Davis.

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Aquapedia background February 11, 2014

Stephen K. Hall

Stephen K. Hall (1951-2010) led the Association of California Water Agencies (ACWA) as its executive director from 1993 until retiring in 2007 from the effects of Amyotrophic Lateral Sclerosis (ALS), or Lou Gehrig’s disease. Hall continued to stay current on water issues and to advocate for legislation on ALS at the state Capitol until he died.

His motto became “As much as I can for as long as I can.”

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Aquapedia background February 11, 2014

William Hammond Hall

William Hammond Hall (1846-1934) is credited with the first proposal of an integrated flood control system with levees, weirs and bypass channels for the Sacramento Valley after his appointment as the first California state engineer.

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Aquapedia background August 25, 2016 Layperson's Guide to California Water California Water Map

Headwaters

Headwaters are the source of a stream or river. They are located at the furthest point from where the water body empties or merges with another. Two-thirds of California’s surface water supply originates in these mountainous and typically forested regions.

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Aquapedia background February 4, 2014 Layperson's Guide to California Water California Water Map

Hetch Hetchy Reservoir and Water System

Hetch Hetchy – a Sierra Miwok word for a type of wild grass – is a valley in Yosemite National Park whose river was dammed to create a water supply for the San Francisco Bay Area. The O’Shaughnessy Dam on the Tuolumne River forms Hetch Hetchy Reservoir.

Owned by the city of San Francisco, Hetch Hetchy Reservoir provides water to 2.7 million residents and businesses in the San Francisco Bay Area.

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Aquapedia background January 30, 2014

Alex Hildebrand

Alex Hildebrand (1913-2012) had an understanding and knowledge of California’s South Delta and San Joaquin River bar none. After retiring early from a career as an engineer for Standard Oil of California, he moved his family to the San Joaquin Valley where he farmed for nearly 50 years while active in water issues and as an advocate for the area.

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Aquapedia background February 4, 2014 Dams Colorado River Basin Map

Hoover Dam

Hoover DamHoover Dam, one of the tallest dams in the United States and a National Historic Landmark that draws tourists from across the globe, is a key reservoir providing flood control, water storage and irrigation along the lower Colorado River. It also is one of the nation’s largest hydroelectric facilities, generating on average about 4 billion kilowatt-hours of hydroelectric power each year, enough electricity to serve more than 1.3 million people in Nevada, Arizona and California.

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Aquapedia background January 30, 2014

Clair A. Hill

Clair A. Hill (1909-1998), a self-made engineer nicknamed “California’s Mr. Water,” built from the ground up an engineering firm that would merge to form the global consulting firm of CH2M HILL.

In 1938 in his hometown of Redding along the Upper Sacramento River in Northern California, he founded Clair A. Hill & Associates. Before merging with CH2M in 1971, the two firms had collaborated on many projects together, including the Lake Tahoe Advanced Wastewater Treatment Facility — the first of its kind in the world.

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Aquapedia background February 10, 2014

Julian B. Hinds

Julian B. Hinds (1881-1977) was Metropolitan Water District of Southern California’s general manager and chief engineer from 1941-1951, but began work on the Colorado River Aqueduct in 1929 soon after the district was organized.

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Aquapedia background February 3, 2014

Edward Hyatt Jr.

Edward Hyatt Jr. (1888-1954) was the state engineer of California from 1927-1950. In a 1928 report he wrote titled “Water is the Life Blood of California — The Division of Engineering and Irrigation of the State Department of Public Works; What it Does and How it Operates,” he called the department the “building organization of California’s state government” and described successes, challenges and responsibilities of his position.

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Aquapedia background February 4, 2014 California Water Map

Hydroelectric Power

Power plant at Shasta DamHydroelectric power is a relatively pollution-free source of electricity generated at a comparatively low cost. Its ability to generate electricity, however, can drop significantly during a drought.

In 2022, hydropower accounted for more than 28% of all renewable electricity generation in the nation, according to the U.S. Department of Energy.

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Aquapedia background September 7, 2016

Hydrographs

A hydrograph illustrates a type of activity of water during a specific time frame. Salinity and acidity are sometimes measured, but the most common types are stage and discharge hydrographs. These graphs show how surface water flow responds to fluxes in precipitation.

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Aquapedia background February 10, 2014

Hydrologic Cycle

Both surface water and groundwater are connected through the hydrologic cycle, essentially the life span of a drop of water.

A drop of water can be birthed, say, by precipitation in the Sierra Nevada range—home to much of California’s runoff.

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I

Overview February 10, 2014

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Aquapedia background February 10, 2014 Colorado River Basin Map Layperson's Guide to the Colorado River Basin

Imperial Valley

Imperial ValleyThe Imperial Valley in the southeastern corner of California receives the Colorado River Basin’s single-largest share of water to support much of the nation’s fruit and vegetable supply and hay for the
cattle and dairy industries.

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Aquapedia background August 15, 2016

Impermeable

Having a surface that does not permit water to move through quickly.

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Aquapedia background February 10, 2014 Layperson's Guide to Integrated Regional Water Management

Integrated Regional Water Management

Integrated Regional Water Management, commonly known as IRWM, aims to collectively manage all aspects of water resources in a region.

This approach includes all constituencies, including those that traditionally have been outside of the water planning and policy process such as tribal representatives.

IRWM reflects an increasing regional self-reliance to meet water supply needs and the recognition that regional water assets, such as groundwater banking, are necessary to reduce the need for water conveyed over long distances.

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Aquapedia background February 10, 2014 Sacramento-San Joaquin Delta Map Layperson's Guide to the Delta

Invasive Species

Invasive water hyacinth surrounds docks and boats in the Sacramento-San Joaquin Delta. Invasive species, also known as exotics, are plants, animals, insects and aquatic species introduced into non-native habitats.

Often, invasive species travel to non-native areas by ship, either in ballast water released into harbors or attached to the sides of boats. From there, introduced species can then spread and significantly alter ecosystems and the natural food chain as they go. Another example of non-native species introduction is the dumping of aquarium fish into waterways.

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Aquapedia background September 8, 2016

Irrigation

Irrigation is the artificial supply of water to grow crops or plants. Obtained from either surface or groundwater, it optimizes agricultural production when the amount of rain and where it falls is insufficient. Different irrigation systems are not necessarily mutually exclusive, but in practical use are often combined. Much of the agriculture in California and the West relies on irrigation. 

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J

Overview February 10, 2014

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Aquapedia background January 30, 2014

C.W. “Bill” Jones

C.W. “Bill” Jones (1918-2003) was an historical water figure known for his pioneering efforts in bringing water deliveries to the agricultural land in the San Joaquin Valley.

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Aquapedia background February 10, 2014

Judge Wanger Rulings

Federal Judge Oliver Wanger overturned a federal scientific study that aimed to protect Delta smelt in the Sacramento-San Joaquin Delta.

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Overview February 10, 2014

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Aquapedia background February 3, 2014

David N. Kennedy

David N. Kennedy (1936-2007) was at the helm as the director of the California Department of Water Resources (DWR) for 15 years, the longest serving director to date, and a champion of the State Water Project (SWP).

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Aquapedia background February 10, 2014

Kesterson Reservoir

The former Kesterson Reservoir in the San Joaquin Valley provides a cautionary tale of the environmental impacts of agricultural drainage.

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Aquapedia background February 10, 2014

Kings River

The 272-mile long Kings River drops sharply in elevation from its headwaters high in the Sierra Nevada Mountain Range on its way to the Central Valley, flowing just south-east of Fresno.

The dramatic descent generates electric power for dams and the river also helps irrigate cropland and provides fresh water to Central Valley communities.

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Klamath Basin Chinook and Coho Salmon

The Klamath Basin’s Chinook salmon and coho salmon serve a vital role in the watershed.

Together, they are key to the region’s water management, habitat restoration and fishing.

However, years of declining population have led to federally mandated salmon restoration plans—plans that complicate the diversion of Klamath water for agriculture and other uses.

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Klamath Basin Water Quality

On the Klamath River, the Upper Klamath Basin’s aquatic ecosystems are naturally very productive due to its phosphorus-rich geology.

However, this high productivity makes the Basin’s lakes vulnerable to water quality problems.

Nutrient loads in the Upper Klamath Basin are a primary driver of water quality problems along the length of the Klamath River, including algal blooms in the Klamath Hydroelectric Project reservoirs. Municipal and industrial discharges of wastewater in the Klamath Falls area add to the nutrient load.

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Aquapedia background February 10, 2014 Layperson's Guide to the Klamath River Basin Klamath River Watershed Map

Klamath River Basin

The Klamath River Basin is one of the West’s most important and contentious watersheds.

The watershed is known for its peculiar geography straddling California and Oregon. Unlike many western rivers, the Klamath does not originate in snowcapped mountains but rather on a volcanic plateau. 

A broad patchwork of spring-fed streams and rivers in south-central Oregon drains into Upper Klamath Lake and down into Lake Ewauna in the city of Klamath Falls. The outflow from Ewauna marks the beginning of the 263-mile Klamath River.

The Klamath courses south through the steep Cascade Range and west along the rugged Siskiyou Mountains to a redwood-lined estuary on the Pacific Ocean just south of Crescent City, draining a watershed of 10 million acres. 

A bounty of resources – water, salmon, timber and minerals – and a wide range of users turned the remote region into a hotspot for economic development and multiparty water disputes (See Klamath River timeline).

Though the basin has only 115,000 residents, there is seldom enough water to go around. Droughts are common. The water scarcity inflames tensions between agricultural, environmental and tribal interests, namely the basin’s four major tribes: the Klamath Tribes, the Karuk, Hoopa Valley and Yurok. Klamath water-use conflicts routinely spill into courtrooms, state legislatures and Congress. 

In 2023, a historic removal of four powers dams on the river began, signaling hope for restoration of the river and its fish and easing tensions between competing water interests. In February 2024, Interior Secretary Deb Haaland announced a “historic” agreement between tribes and farmers in the basin over chronic water shortages. The deal called for a wide range of river and creek restoration work and modernization of agricultural water supply infrastructure. 

Water Development

Farmers and ranchers have drawn irrigation water from basin rivers and lakes since the late 1900s. Vast wetlands around Upper Klamath Lake and upstream were drained to grow crops. Some wetlands have been restored, primarily for migratory birds.

In 1905, the federal government authorized construction of the Klamath Project, a network of irrigation canals, storage reservoirs and hydroelectric dams to grow an agricultural economy in the mostly dry Upper Basin. The Project managed by the U.S. Bureau of Reclamation irrigates about 240,000 acres and supplies the Lower Klamath Lake and Tule Lake national wildlife refuges managed by the U.S. Fish and Wildlife Service.

Klamath River Basin

Water Management

Since 1992, federal mandates to restore populations of fish protected by the Endangered Species Act have led in some dry years to drastic cuts in water deliveries to Klamath Project irrigators.

Water in Upper Klamath Lake must be kept above certain levels for the endangered shortnose and Lost River suckers. Lake levels and Klamath River flows below Iron Gate Dam also must be regulated for the benefit of threatened coho salmon (See Klamath Basin Chinook and Coho Salmon).

Conflict

In 2001, Reclamation all but cut off irrigation water to hundreds of basin farmers and ranchers, citing a severe drought and legal obligations to protect imperiled fish. In response, thousands of farmers, ranchers and residents flocked to downtown Klamath Falls to form a “bucket brigade” protest, emptying buckets of water into the closed irrigation canal. The demonstrations stretched into the summer, with protestors forcing open the irrigation headgates on multiple occasions. Reclamation later released some water to help farmers.

Karuk fisheries workers netting salmon in Klamath River.In September 2002, a catastrophic disease outbreak in the lower Klamath River killed tens of thousands of ocean-going salmon. The Pacific Coast Federation of Fishermen’s Associations sued Reclamation, alleging the Klamath Project’s irrigation deliveries had violated the Endangered Species Act. The fishing industry eventually prevailed, and a federal court ordered an increase to minimum flows in the lower Klamath.

Compromise

The massive salmon kill and dramatic water shut-off set in motion a sweeping compromise between the basin’s many competing water interests: the Klamath Basin Restoration Agreement and the Klamath Hydroelectric Settlement Agreement. The 2010 agreements included:

  • Removal of four hydroelectric dams
  • $92.5 million over 10 years to pay farmers to use less water, increase reservoir storage and help pay for water conservation and groundwater management projects.
  • $47 million over 10 years to buy or lease water rights to increase flows for salmon recovery.

Dam Removals

Congress never funded the two agreements, allowing the key provisions to expire. The restoration accord dissolved in 2016. The hydroelectric pact, however, was revived in an amended version that did not require federal legislation.

The new deal led to the nation’s largest dam removal project ever undertaken.

The Klamath's Copco No. 2 DamCalifornia and Oregon formed a nonprofit organization called the Klamath River Renewal Corporation to take control of the four essentially obsolete power dams – J.C. Boyle, Copco No. 1, Copco No. 2 and Iron Gate – and oversee a $450 million dam demolition and river restoration project.

Taking out the dams will open more than 420 miles of river and spawning streams that had been blocked for more than a century, including cold water pools salmon and trout need to survive the warming climate.  

Demolition crews took out the smallest dam in 2023 and the others were scheduled to come down by the end of 2024.

The images of yellow heavy machinery tearing into the dam’s spillway gates prompted a cathartic release for many who have been fighting for decades to open this stretch of the Klamath.

“I’m still in a little bit of shock,” said Toz Soto, the Karuk fisheries program manager. “This is actually happening…It’s kind of like the dog that finally caught the car, except we’re chasing dam removal.”

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Aquapedia background February 10, 2014

Klamath River Basin Chronology

1849-1850 Gold discovered in the Lower Klamath Basin. Farms and ranches established in the Scott and Shasta valleys.

1855 Klamath River Reservation established on the Lower Klamath River.

1864 Hoopa Valley Tribe and Klamath Tribes cede most of their lands for settlement but retain large reservations.

1868 Two farmers dig first irrigation ditch in the Upper Klamath Basin.

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Aquapedia background April 13, 2021

Lois Krieger

Lois Krieger (1917–2014) was one of the true pioneers of the California water world. She was the first woman elected chair of the Metropolitan Water District of Southern California’s board of directors, the first female president of the Association of California Water Agencies and a long-time champion of the wise development and use of water in the state.

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Aquapedia background September 1, 2016 Lake Tahoe Lake Mead Mono Lake Diamond Valley Lake

Lakes

Definition

Lake TahoeA lake is an inland standing body of water.

Lake, Pond or Wetland?

Scientifically and legislatively, lakes are indistinguishable from ponds, but lakes generally are considered to be longer and deeper lentic, or still, waters. In the 18th and 19th centuries, scientists attempted to distinguish the two more formally, stating that ponds were shallow enough to allow sunlight to penetrate to the bottom, but this exists today as an unofficial point.

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Aquapedia background August 30, 2016

Lake Havasu & Parker Dam

Lake Havasu is a reservoir on the Colorado River that supplies water to the Colorado River Aqueduct and Central Arizona Project. It is located at the California/Arizona border, approximately 150 miles southeast of Las Vegas, Nevada and 30 miles southeast of Needles, California.

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  • Layperson's Guide to the Colorado River
Aquapedia background August 30, 2016

Lake Mathews

Situated in southwest Riverside County near the Santa Ana Mountains – about 60 miles southeast of Los Angeles – Lake Mathews is a major reservoir in Southern California.

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  • Layperson's Guide to the Colorado River
Aquapedia background February 11, 2014 Colorado River Basin Map Elwood Mead Colorado River Hoover Dam

Lake Mead

Lake Mead is the main reservoir formed by Hoover Dam on the border between Southern Nevada and northwestern Arizona.

Created in the 1930s as part of Hoover Dam [see also Elwood Mead], Lake Mead provides water storage in the Lower Basin of the Colorado River. The reservoir is designed to hold 28,945,000 acre-feet of water and at 248 square miles its capacity is the largest in United States.

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Aquapedia background February 11, 2014

Lake Perris

The State Water Project facility Lake Perris, below the San Bernardino Mountains, stores water for Inland Empire cities such as San Bernardino and Riverside. [See also Santa Ana River.]

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Aquapedia background February 11, 2014 Colorado River Basin Map

Lake Powell and Glen Canyon Dam

Image shows Glen Canyon Dam with Lake Powell in the background.The construction of Glen Canyon Dam in 1964 created Lake Powell. Both are located in north-central Arizona near the Utah border. Lake Powell acts as a holding tank for outflow from the Colorado River Upper Basin States: Colorado, New Mexico, Utah and Wyoming.

The water stored in Lake Powell is used for recreation, power generation and delivering water to the Lower Basin states of California, Arizona, and Nevada. 

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Aquapedia background February 11, 2014 Lakes Unwelcome Visitors Layperson's Guide to Climate Change and Water Resources

Lake Tahoe

Lake Tahoe is one of the world’s most beautiful yet vulnerable lakes. Renowned for its remarkable clarity, Tahoe straddles the Nevada-California border, stretching 22 miles long and 12 miles wide in a granitic bowl high in the Sierra Nevada.

Tahoe sits 6,225 feet above sea level. Its deepest point is 1,645 feet, making it the second-deepest lake in the nation, after Oregon’s Crater Lake, and the tenth deepest in the world.

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Aquapedia background February 11, 2014

Land Retirement

Land retirement is a practice that takes agricultural lands out of production due to poor drainage and soils containing high levels of salt and selenium (a mineral found in soil).

Typically, landowners are paid to retire land. The purchaser, often a local water district, then places a deed restriction on the land to prevent growing crops with irrigation water (a source of salt). Growers in some cases may continue to farm using rain water, a method known as dry farming.

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Aquapedia background February 11, 2014 California Groundwater Map Layperson's Guide to Groundwater

Land Subsidence

Land subsidence is the lowering of the land-surface elevation due to changes that take place underground.

Throughout California, subsidence has damaged buildings, aqueducts, well casings, bridges and highways. Common causes include pumping water, oil or gas, dissolution of limestone aquifers known as sinkholes, drainage of organic soils and initial wetting of dry soils, according to the U.S. Geological Survey.

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Aquapedia background March 18, 2015

Landsat

The Landsat satellite program is a series of Earth-observing satellite missions jointly managed by the National Aeronautics and Space Administration and the U.S. Geological Survey.  Launched in 1972, Landsat is the longest continuous global record of Earth observations.  Landsat data is used to evaluate agricultural production.

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Aquapedia background August 15, 2016

Leach

Applying water in excess of a crop’s needs to flush out salts from the root zone.

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Aquapedia background February 11, 2014 Colorado River Basin Map

Lee Ferry

Lee Ferry on the Arizona-Utah border is a key dividing point between the Colorado River’s Upper and Lower basins.

This split is important when it comes to determining how much water will be delivered from the Upper Basin to the Lower Basin [for a description of the Upper and Lower basins, visit the Colorado River page].

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Aquapedia background February 11, 2014

Levees

California would not exist as it does today were it not for the extensive system of levees, weirs and flood bypasses that have been built through the years, particularly in the Sacramento-San Joaquin Delta.

These levees have been in place dating back to 1850, when California first joined the union.

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Aquapedia background February 11, 2014 California Water Map California Water Map, Spanish

Los Angeles Aqueduct and Owens Valley

Los Angeles Aqueduct Cascades The Owens Valley in eastern California helped transform distant Los Angeles into today’s sprawling megalopolis.

More than 100 years ago, Los Angeles recognized the need to augment local water supplies and decided to tap faraway sources.

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Aquapedia background February 11, 2014 California Water Map Layperson's Guide to California Water

Los Angeles River

The Los Angeles River is gradually being transformed from a giant, trash-strewn stormwater channel to a recreational and open space corridor that continues to provide flood control.

Deadly floods in the 1930s led the U.S. Army Corps of Engineers to straighten and pave nearly all 52 miles of the river channel in concrete. The trough was designed to keep flood water from destroying property, to manage the discharges from sewage treatment plants and to flush stormwater to the Pacific Ocean.

Since the 1990s, a grassroots campaign to restore some of the natural character of the river has gained political traction.

Los Angeles has the lowest ratio of open space per capita of any major American city, due to rapid growth and poor urban planning.

A bill passed by the state Legislature in 1992 established a Los Angeles River Conservancy to develop comprehensive planning strategies along the concrete corridor.

Additionally, a citizens’ group, Friends of the Los Angeles River, has helped coordinate the cleanup and rejuvenation of the river.

In the past, river advocates considered painting the river channel blue to give it a more natural look.

In 2010, the U.S. EPA deemed the river navigable and subject to the protections of the Clean Water Act. A year later, the Army Corps permitted kayaking along soft-bottom stretches north of downtown.

In 2014, the Army Corps recommended approval of Los Angeles County’s plan to restore habitat, widen the river, create wetlands, and invite new commercial and residential development. The county Board of Supervisors approved the Los Angeles River Master Plan in 2022.

In the winter of 2024, the river captured near-record precipitation from a series of intense atmospheric rivers, thanks to drain clearing and dredging of debris, Army Corps officials said.​

Los Angeles River supporters are looking beyond the river’s banks toward improved management of the Los Angeles River watershed as a whole. Advocates seek a strategy that integrates and coordinates the management of water quality, flood control and habitat restoration across jurisdictional boundaries.

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Aquapedia background February 11, 2014 Layperson's Guide to the Colorado River Basin Colorado River Basin Map

Lower Colorado River Multispecies Conservation Program

In 2005, the Interior Department launched a program to recover 27 species in the lower Colorado River, including seven the federal government has deemed threatened or endangered or threatened with extinction. The species include fish, birds, bats, mammals, insects, amphibians, reptiles, rodents and plants

The Lower Colorado River Multispecies Conservation Program has a 50-year plan to create at least 8,132 acres of new habitat and restore habitat that has become degraded.

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Aquapedia background February 11, 2014

Robert B. Marshall

Robert B. Marshall (1867-1949), whose career at the U.S. Geological Survey culminated in 1908 when he became chief geographer for the entire USGS, first proposed the concept of a statewide water plan for a series of dams, canals and aqueducts to bring water to California’s Central Valley.

As a result of his 1919 Marshall Plan, he earned the nickname of “Father of the Central Valley Project.” According to the California Department of Water Resources, the Marshall Plan became the precursor of the first State Water Plan in 1930.

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Aquapedia background February 3, 2014

Don McCrea

Don McCrea was one of the founding members of the Water Education Foundation and signed its original Articles of Incorporation in 1977.

His background was in power and energy issues, including hydrology and the state’s hydrologic system, from a career at the Pacific Gas & Electric Company in San Francisco. He was involved in the development of the State Water Project as a proponent of the value of hydroelectricity.

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Aquapedia background February 11, 2014 Colorado River Basin Map Elwood Mead Colorado River Hoover Dam

Lake Mead

Lake Mead is the main reservoir formed by Hoover Dam on the border between Southern Nevada and northwestern Arizona.

Created in the 1930s as part of Hoover Dam [see also Elwood Mead], Lake Mead provides water storage in the Lower Basin of the Colorado River. The reservoir is designed to hold 28,945,000 acre-feet of water and at 248 square miles its capacity is the largest in United States.

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Aquapedia background February 3, 2014

Elwood Mead

Elwood Mead (1858-1936) was the commissioner of the U.S. Bureau of Reclamation during the era of the development of Hoover Dam on the Colorado River between Arizona and Nevada, Grand Coulee Dam in Washington and Owyhee Dam in Oregon, among other large water projects.

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Aquapedia background September 1, 2016

Meadows

While less a scientific term than a colloquial one, meadows are defined by their aquatic, soil and vegetative properties.

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Aquapedia background February 11, 2014

Mendota Pool

The Mendota Pool, located at the confluence of the San Joaquin River and Kings River in California’s Central Valley, is the terminus of a long journey for water from the Sacramento River.

After being diverted, the Sacramento River water heads south from the Sacramento San Joaquin Delta via the 117-mile long Delta-Mendota Canal.

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Aquapedia background February 11, 2014

Merced River

The Merced River is one of three major rivers that empty in the San Joaquin Valley from the east, along with the Tuolumne and the Stanislaus rivers. 

With the help of these tributaries, the San Joaquin River irrigates millions of acres of cropland in the San Joaquin Valley.

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Aquapedia background February 11, 2014

Colorado River Delta (in Mexico)

The Colorado River Delta is located at the natural terminus of the Colorado River at the Gulf of California, just south of the U.S.-Mexico border. The desert ecosystem was formed by silt flushed downstream from the Colorado and fresh and brackish water mixing at the Gulf.

The Colorado River Delta once covered 9,650 square miles but has shrunk to less than 1 percent of its original size due to human-made water diversions.

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Aquapedia background February 11, 2014

Colorado River Water and Mexico

The Mexican Water Treaty of 1944 committed the U.S. to deliver 1.5 million acre-feet of water to Mexico on an annual basis, plus an additional 200,000 acre-feet under surplus conditions. The treaty is overseen by the International Boundary and Water Commission.

Colorado River water is delivered to Mexico at Morelos Dam, located 1.1 miles downstream from where the California-Baja California land boundary intersects the river between the town of Los Algodones in northwestern Mexico and Yuma County, Ariz.

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Aquapedia background September 7, 2016 Layperson's Guide to California Water California Water Map

Microplastics

Microplastics – plastic debris measuring less than 5 millimeters – are an increasing water quality concern. They enter waterways and oceans as industrial microbeads from various consumer products or larger plastic litter that degrades into small bits.

Microbeads have been used in exfoliating agents, cosmetic washes and large-scale cleaning processes. Microplastics are used pharmaceutically for efficient drug delivery to affected sites in patients’ bodies and by textile companies to create artificial fibers. 

Part of their appeal to hygienic and medical interests is their tendency to absorb surrounding chemicals and later release them. This quality makes microplastics ideal as small commercial sponges, but poses a hazard as water contaminants, potentially carrying harmful chemicals through the food chain as they are ingested.

Challenges of Removing Microplastics 

Microplastics disperse easily and widely throughout surface waters and sediments. UV light, microbes and erosion degrade the tiny fragments, making them even smaller and more difficult for wastewater treatment plants to remove.

The particles, usually made of polyethylene or polypropylene plastic, take thousands of years to biodegrade naturally. It takes prohibitively high temperatures to break microplastics down fully. Consequently, most water treatment plants cannot remove them.  

The health effects of consumption are currently under investigation.  

Responses

Many advocacy groups have published lists of products containing microbeads to curb their purchase and pollution.

The U.S. Environmental Protection Agency regulates microbeads in industrial, but not domestic, wastewater. 

Federal law required microbeads to be phased out of rinse-off cosmetics beginning in July 2017. Dozens of states also regulate microbeads in products. California has the strictest limitation, prohibiting even the use of biodegradable microbeads.

Microplastics in California Water

In 2019, the San Francisco Estuary Institute published a study estimating that 7 trillion pieces of microplastic enter San Francisco Bay annually from stormwater runoff, about 300 times the amount in all wastewater treatment effluent entering the bay.

California lawmakers in 2018 passed a package of bills to raise awareness of the risks of microplastics and microfibers in the marine environment and drinking water. As directed by the legislation, the State Water Resources Control Board in 2020 adopted an official definition of microplastics in drinking water and in 2022 developed the world’s standardized methods for testing drinking water for microplastics.

The water board was expected by late 2023 to begin testing for microplastics in untreated drinking water sources tapped by 30 of the state’s largest water utilities. After two years, the testing was expected to extend to treated tap water served to consumers. A progress report and recommendations for policy changes or additional research are required by the end of 2025.

  • Read the EPA's summary of microplastic risks
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Aquapedia background August 31, 2016

Mojave River

Flowing into the heart of the Mojave Desert, the Mojave River exists mostly underground. Surface channels are usually dry absent occasional groundwater surfacing and flooding from extreme weather events like El Niño. 

  • Read the Final Judgment for Mojave Basin's Adjudication
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Aquapedia background February 11, 2014 Lakes Public Trust Doctrine

Mono Lake

Mono Lake is an inland sea located east of Yosemite National Park near the Nevada border. It became the focus of a major environmental battle from the 1970s to the 1990s.

The lake has a surface area of about 70 square miles and is the second largest lake in California and one of the oldest in North America. Its salty waters occupy former volcanic craters. The old volcanoes contribute to the geology of the lake basin, which includes sulfates, salt and carbonates.

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Aquapedia background February 11, 2014

Monterey Amendment

The Monterey Amendment, a 1994 pact between Department of Water Resources and State Water Project contractors, helped ease environmental stresses on the Sacramento San Joaquin Delta.

As part of large-scale restructuring of water supply contracts, the Monterey Amendment allowed for storage of excess flows during wet years in groundwater banks and surface storage reservoir. This stored water could then be used later during dry periods or to help the Delta.

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Aquapedia background January 30, 2014

Adolph Moskovitz

Adolph Moskovitz (1923-1996) is remembered as one of the leading water resources attorneys in the country and has been described as “brilliant” by his many peers in the legal profession.

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Aquapedia background February 10, 2014

John Muir

John Muir (1838-1914) was a famous and influential naturalist and conservationist who founded the Sierra Club in 1892 and was its president until he died. Throughout his life, this man from Scotland was also a farmer, inventor, sheepherder, explorer and writer.

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Aquapedia background February 11, 2014

William Mulholland

William Mulholland (1855-1935), an immigrant from Ireland, is infamous in the history of California water and the state’s water wars for both his far-sightedness and no-holds-barred approach to delivering a controversial water supply to Southern California. He is a love-hate character with a story that has many tellings, including in the 1974 fictional movie, Chinatown.

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Aquapedia background February 11, 2014

National Environmental Policy Act

Passed in 1970, the federal National Environmental Policy Act requires lead public agencies to prepare and submit for public review environmental impact reports and statements on major federal projects under their purview with potentially significant environmental effects.

According to the Department of Energy, administrator of NEPA:

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Aquapedia background July 25, 2017

Natural Variability

Variations in the statistical analysis of the climate on all time and space scales beyond that of individual weather events is known as natural variability. Natural variations in climate over time are caused by internal processes of the climate system, such as El Niño, and phenomena such as volcanic activity and variations in the output of the sun.

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Aquapedia background February 11, 2014 Dams

New Melones Dam

Completed in 1979, the New Melones Dam on California’s Stanislaus River includes a 2.4 million acre-feet reservoir and a power-generating capacity of 283 megawatts.

The Central Valley Project facility was built to help with irrigation, flood control and power production. It replaced an older dam from the 1920s that supplied water for agriculture to two local irrigation districts.

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Aquapedia background February 11, 2014

Nimbus Dam

A part of the federal Central Valley Project, the Nimbus Dam and its after bay, Lake Natoma, are located 7 miles downstream of Folsom Dam on the American River.

The dam regulates American River flows. Other associated facilities are the Nimbus Powerplant, the Nimbus Salmon and Steelhead Hatchery and the Folsom South Canal. [see also Northern California Water Tours.]

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Aquapedia background February 11, 2014

Nitrate Contamination

Nitrate—the oxidized form of dissolved nitrogen— is the main source of nitrogen for plants. It occurs naturally in soil and dissipates when the soil is extensively farmed. Thus, nirtrogen fertilizers are applied to replenish the soil. However, these nitrates can be toxic, especially when they enter the food chain via groundwater and surface water.

In California, the State Water Resources Control Board lists nitrate as one of California’s most challenging and growing water problems.

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Aquapedia background February 11, 2014

North Coast Rivers

Also known as the Lost Coast, California’s remote north coast is home to mostly undeveloped rivers.

The Klamath, Trinity, Eel, Russian and Smith rivers are the major northern streams that drain this sparsely populated, forested coastal area that stretches from San Francisco to the Oregon border.

These rivers and their tributaries flow west to the Pacific Ocean and account for about 40 percent of the state’s total runoff.

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Aquapedia background May 21, 2020 Layperson's Guide to the Delta Unwelcome Visitors

Nutria

Nutria are large, beaver-like rodents native to South America that have caused alarm in California since their rediscovery along Central Valley rivers and other waterways in 2017.

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Aquapedia background August 25, 2016

One Hundred Year Flood

Risk Assessment, Not a Timeline

Contrary to popular belief, “100-Year Flood” does not refer to a flood that happens every century. Rather, the term describes the statistical chance of a flood of a certain magnitude (or greater) taking place once in 100 years. It is also accurate to say a so-called “100-Year Flood” has a 1 percent chance of occurring in a given year, and those living in a 100-year floodplain have, each year, a 1 percent chance of being flooded.

  • Read more
  • Layperson's Guide to Flood Management
Aquapedia background February 11, 2014 Layperson's Guide to the State Water Project Dams

Oroville Dam

Oroville DamOroville Dam is the tallest in the United States and impounds the largest reservoir in California’s State Water Project, which brings water to 27 million residents and 750,000 acres of farmland.

Completed in 1968, the 770-foot earthfill embankment impounds the northern Sierra Nevada’s Feather River, creating a reservoir that can hold 3.5 million acre-feet of water.

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Aquapedia background February 11, 2014

Overdraft

Overdraft occurs when, over a period of years, more water is pumped from a groundwater basin than is replaced from all sources – such as rainfall, irrigation water, streams fed by mountain runoff and intentional recharge. [See also Hydrologic Cycle.]

While many of its individual aquifers are not overdrafted, California as a whole uses more groundwater than is replaced.

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Aquapedia background August 30, 2016

Owens Lake

Owens Lake is a dry lake at the terminus of the Owens River just west of Death Valley and on the eastern side of the Sierra Nevada. For at least 800,000 years, the lake had a continuous flow of water, until 1913 when the Los Angeles Department of Water and Power (LADWP) completed the 233-mile Los Angeles Aqueduct to supplement the budding metropolis’ increasing water demands.

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Aquapedia background February 11, 2014 California Water Map Layperson's Guide to California Water

Pacific Flyway

Sacramento National Wildlife RefugeThe Pacific Flyway is one of four major North American migration routes for birds, especially waterbirds, and stretches from Alaska in the north to Patagonia in South America.

Each year, birds follow ancestral patterns as they travel the flyway on their annual north-south migration. Along the way, they need stopover sites such as wetlands with suitable habitat and food supplies. In California, 95 percent of historic wetlands have been lost, yet the Central Valley hosts some of the world’s largest populations of wintering birds. 

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Aquapedia background August 30, 2016

Lake Havasu & Parker Dam

Lake Havasu is a reservoir on the Colorado River that supplies water to the Colorado River Aqueduct and Central Arizona Project. It is located at the California/Arizona border, approximately 150 miles southeast of Las Vegas, Nevada and 30 miles southeast of Needles, California.

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  • Layperson's Guide to the Colorado River
Aquapedia background September 8, 2016

Parts-per Notation

For both small and large concentrations, parts-per notation is a very convenient way to communicate numbers that would ordinarily have many zeros (either before or after a decimal point). For example, 3 ppt (parts per trillion) is much cleaner than reporting 0.000000000003. Additionally, it is important to distinguish what units are being described. Is it 3 particles per trillion particles? 3 grams per trillion grams? In other words, parts-per notation offers a unit-less ratio, and in scientific literature the true units are either directly stated or implied from context.

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Aquapedia background February 11, 2014

Pelagic Fish

Pelagic fish are those that live near the water’s surface rather than on the bottom. In California, pelagic fish species include the Delta smelt, longfin smelt, striped bass and salmon.

In California, the fate of pelagic fish has been closely tied to the use of the water that supports them.

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Aquapedia background August 15, 2016

Percolation

Movement of water down through the soil toward the water table.

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Aquapedia background August 15, 2016

Permeability

Capability of soil or rock to transmit water.

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Aquapedia background February 11, 2014

Fred T. Perris

Fred T. Perris (1837-1916) became the chief engineer and superintendent of construction of the California Southern Railway. A civil engineer, he also played a role in surveying and taking water measurements in San Bernardino and Los Angeles counties. The Lake Perris State Recreation Area and the city of Perris are named after him.

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Lake Perris

The State Water Project facility Lake Perris, below the San Bernardino Mountains, stores water for Inland Empire cities such as San Bernardino and Riverside. [See also Santa Ana River.]

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Pesticide Contamination

Pesticides find their way into creeks, rivers and the oceans, threatening aquatic life and the safety of drinking water.

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Pit River

The Pit River is the longest tributary of the Sacramento River and largest river in northeast California. It connects to the Sacramento River at Shasta Lake and has headwaters at the confluence of its two tributaries – the North and South Forks.

  • Read the California Department of Fish and Game's 2008 Pit River Summary Report
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Point Source vs. Nonpoint Source Pollution

Point Source Pollution

Point sources release pollutants from discrete conveyances, such as a discharge pipe, and are regulated by federal and state agencies. The main point source dischargers are factories and sewage treatment plants, which release treated wastewater.

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  • Layperson's Guide to California Wastewater
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Carley V. Porter

Carley V. Porter (1906-1972) was the longtime chairman of the California Legislature’s Assembly Committee on Water who has two historical and important water laws named after him. He was a Democrat from Compton in Los Angeles County and a teacher before being elected to the Assembly.

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Potable Water

Photo of drinking water filling a glass over the kitchen sink. Potable water, also known as drinking water, comes from surface and ground sources and is treated to levels that that meet state and federal standards for consumption.

Water from natural sources is treated for microorganisms, bacteria, toxic chemicals, viruses and fecal matter. Drinking raw, untreated water can cause gastrointestinal problems such as diarrhea, vomiting or fever.

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John Wesley Powell

John Wesley Powell (1834-1902) was historic and heroic for being first to lead an expedition down the Colorado River in 1869. A major who lost an arm in the Civil War Battle of Shiloh, he was an explorer, geologist, geographer and ethnologist.

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Lake Powell and Glen Canyon Dam

Image shows Glen Canyon Dam with Lake Powell in the background.The construction of Glen Canyon Dam in 1964 created Lake Powell. Both are located in north-central Arizona near the Utah border. Lake Powell acts as a holding tank for outflow from the Colorado River Upper Basin States: Colorado, New Mexico, Utah and Wyoming.

The water stored in Lake Powell is used for recreation, power generation and delivering water to the Lower Basin states of California, Arizona, and Nevada. 

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Aquapedia background August 30, 2016 Seven Oaks Dam

Prado Dam

Prado Dam in Southern CaliforniaPrado Dam – built in 1941 in response to the Santa Ana River’s flood-prone past – separates the river into its upper and lower watersheds. After the devastation of the deadly Los Angeles Flood of 1938 that impacted much of Southern California, it became evident that flood protection was woefully inadequate, prompting the U.S. Army Corps of Engineers to construct Prado Dam.

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  • Layperson's Guide to Flood Management
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Prescriptive Rights

Prescriptive Rights are water use rights gained illicitly that evolve into a title. Typically this occurs with rights to chronically overdrafted groundwater basins gained through trespass or unauthorized use.

In California, the California Supreme Court developed the doctrine of prescriptive rights in 1949.

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Aquapedia background February 11, 2014 Layperson's Guide to Water Rights Law Layperson's Guide to California Water

Public Trust Doctrine

Rooted in Roman law, the public trust doctrine recognizes the public right to many natural resources including “the air, running water, the sea and its shore.”

The doctrine requires the sovereign, or state, to hold in trust designated resources for the benefit of the people. Traditionally, the public trust applied to commerce and fishing in navigable waters, but its uses were expanded in California in 1971 to include fish, wildlife, habitat and recreation.

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Pueblo Water Rights

In addition to riparian and appropriative water rights, there are two other types of surface water rights in California: pueblo rights and federal reserved rights.

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Q

Overview February 11, 2014

Q

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Quagga mussel

Quagga musselsA troublesome invasive species is the quagga mussel, a tiny freshwater mollusk that attaches itself to water utility infrastructure and reproduces at a rapid rate, causing damage to pipes and pumps.

First found in the Great Lakes in 1988 (dumped with ballast water from overseas ships), the quagga mussel along with the zebra mussel are native to the rivers and lakes of eastern Europe and western Asia, including the Black, Caspian and Azov Seas and the Dneiper River drainage of Ukraine and Ponto-Caspian Sea.  

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Aquapedia background February 11, 2014 Colorado River Basin Map Layperson's Guide to the Colorado River Basin

Quantification Settlement Agreement

The Quantification Settlement Agreement (QSA), signed in 2003, defined the rights to a portion of Colorado River water for the San Diego County Water Authority, Coachella Valley Water District, Imperial Irrigation District and the Metropolitan Water District of Southern California.

The QSA responded to California consistently using more than its annual Colorado River entitlement of 4.4 million acre-feet. Additionally, the water needs of six other Colorado River Basin states had grown, making the river’s shared use increasingly crucial.

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R

Overview February 11, 2014

R

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Reclamation

Draining land to ‘reclaim’ it for use in agriculture, wildlife habitat or development.

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Recharge

Generally, “recharge” describes the flow to groundwater storage from precipitation, irrigation, spreading basins and other sources of water.

Artificial recharge is the purposeful addition of surface water to a groundwater basin by human activity.  

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Aquapedia background February 11, 2014 Layperson's Guide to Water Recycling Colorado River Shortages Drive Major Advances in Recycled Sewage Water Use

Recycled Water

Image shows samples of cleaned wastewater before and after reverse osmosis filtration at the Pure Water Southern California Demonstration Plant in Carson.All water is naturally recycled and reused as part of the hydrologic cycle. Recycled water is also produced by purifying wastewater for safe use in drinking (potable) water and for non-potable uses such as irrigation.

Recycling wastewater provides a new, costly but renewable water resource that can bolster local water supplies, save energy and reduce the amount of sewage treatment plant effluent emptied into rivers and oceans.

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Red Bluff Fish Passage Improvement Project and Diversion Dam

The Red Bluff Diversion Dam, its gates raised since 2011 to allow fish passage, spans the Sacramento River two miles southeast of Red Bluff on the Sacramento River in Tehama County. It is owned by the Bureau of Reclamation and operated and maintained by the Tehama-Colusa Canal Authority.

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Regional Water Quality Control Boards in California

There are nine regional water quality control boards statewide.

The nine Regional Boards are semi-autonomous and are comprised of seven part-time Board members appointed by the Governor and confirmed by the Senate. Regional boundaries are based on watersheds and water quality requirements are based on the unique differences in climate, topography, geology and hydrology for each watershed. Each Regional Board makes critical water quality decisions for its region, including setting standards, issuing waste discharge requirements, determining compliance with those requirements, and taking appropriate enforcement actions.

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Marc Reisner

Marc Reisner (1948-2000), an environmental writer who became a celebrity in the water world, was the author of Cadillac Desert: The American West and Its Disappearing Water (1986), a best-seller about Western water history and politics and a full-blown critique of 20th century water development, especially in California and the West. “Based on 10 years of research, Cadillac Desert is a stunning expose and a dramatic, provocative history of the creation of an Eden — an Eden that may be only a mirage,” according to the book’s back flap.

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Remote Sensing

Remote sensing technology brings greater information and detail about things such as levee integrity, microclimate conditions in a farm field and the depth of the Sierra Nevada snowpack. If not from satellite cameras, the imagery is often relayed through high-flying aircraft.

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Riparian Rights

Surface water is water found in rivers, lakes, streams, and ponds. There are a limited number of instances in which water in a defined underground channel is classified as surface water. There are several types of water rights that apply to surface water.

A landowner whose property borders a river has a right to use water from that river on his land. This is called riparian rights.

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Ronald B. Robie

Ronald B. Robie, an associate justice on the California Court of Appeal, Third Appellate District, has made his mark on state water issues during a career in public service that has spanned all three branches of government.

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Theodore “Teddy” Roosevelt

Theodore “Teddy” Roosevelt (1858-1919) was the 26th president of the United States who established the U.S. Bureau of Reclamation and created the U.S. Forest Service.

During his term of office from 1901-1909, he is credited for his efforts on conservation, increasing the number of national forests, protecting land for the public and promoting irrigation projects. For Roosevelt, water was instrumental to developing the Western states.

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Runoff

Snowmelt and runoff near the California Department of Water Resources snow survey site in the Sierra Nevada east of Sacramento.Runoff is the water that is pulled by gravity across land’s surface, replenishing groundwater and surface water as it percolates into an aquifer or moves into a river, stream or watershed.

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Russian River

The Russian River is one of the major northern streams that drain the sparsely populated, forested coastal area that stretches from San Francisco to the Oregon border.

Other North Coast waterways include the Klamath, Trinity, Eel and Smith [see also North Coast Rivers]. These rivers and their tributaries flow west to the Pacific Ocean and account for about 40 percent of the state’s total runoff.

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S

Overview February 11, 2014

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Sacramento River

California’s largest river, the Sacramento, provides 31 percent of the state’s surface water runoff. 

Once called “the Nile of the West,” the Sacramento River drains the inland slopes of the Klamath Mountains, the Cascade Range, the Coast Ranges and the western slopes of the northern Sierra Nevada. The river stretches some 384 miles from its headwaters near Mount Shasta to the Sacramento-San Joaquin Delta.

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Aquapedia background February 11, 2014 Layperson's Guide to the Delta Sacramento-San Joaquin Delta Map

Sacramento-San Joaquin Delta

The Sacramento-San Joaquin Delta is California’s most crucial water and ecological resource. It is the largest freshwater tidal estuary of its kind on the west coast of the Americas, providing important habitat for birds on the Pacific Flyway and for fish that live in or pass through the Delta. It also the hub of California’s two largest surface water delivery projects, the State Water Project and the federal Central Valley Project. The Delta provides a portion of the drinking water for 27 million Californians and irrigation water for large portions of the state’s $50 billion agricultural industry.

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Sacramento-San Joaquin Delta and Salinity

The Sacramento-San Joaquin Delta always has been at the mercy of river flows and brackish tides.

Before human intervention, salty ocean water from the San Francisco Bay flooded the vast Delta marshes during dry summers when mountain runoff ebbed. Then, during winter, heavy runoff from the mountains repelled sea water intrusion.

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Sacramento-San Joaquin Delta Canal/Tunnel Proposals

The Sacramento-San Joaquin Delta has been the hub of California’s water system for more than 50 years and along the way water experts have struggled to balance the many competing demands placed on the estuary—the largest freshwater tidal estuary on the West Coast.

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Sacramento-San Joaquin Delta Chronology

1772 First recorded sighting of the Bay Delta by Spanish explorers.

1849 Settlers begin farming in the Delta.

1861 Reclamation District Act authorized, allowing drainage of Delta lands and construction of sturdier flood control levees.

1879 The striped bass is brought by rail from the East Coast to the Delta.

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Sacramento-San Joaquin Delta Cross Channel

The 6,000-foot Delta Cross Channel diverts water from the Sacramento River into a branch of the Mokelumne River, where it follows natural channels for about 50 miles to the Jones Pumping Plant intake channel. Located near the State Water Project’s Harvey O.

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Sacramento-San Joaquin Delta Fish and Wildlife

The Sacramento-San Joaquin Delta supports more than 55 fish species and more than 750 plant and wildlife species.

Over times, the home of these species-the Sacramento-San Joaquin Delta ecosystem-has been impacted for many decades by human activities, such as gold mining, flood protection and land reclamation. Along the way, more than 200 exotic species have been intentionally or accidentally introduced.

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Sacramento-San Joaquin Delta Inflow Outflow

The fresh water inflow and outflow of the Sacramento-San Joaquin Delta is critical to its vitality and survival.

Freshwater flows from the Delta meets saltwater from the ocean near Suisun Marsh located to the east of San Francisco Bay. Suisun Marsh and adjoining bays are the brackish transition between fresh and salt water. But the location of that transition is not fixed.

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Sacramento-San Joaquin Delta Land Use and Boundaries

The Sacramento-San Joaquin Delta includes approximately 500,000 acres of waterways, levees and farmed lands extending over portions of six counties: Alameda, Contra Costa, Sacramento, San Joaquin, Solano and Yolo.

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Sacramento-San Joaquin Delta Levees

Roughly 1,115 miles of levees protect farms, cities, schools and people in and around the Sacramento-San Joaquin Delta, a crucial conduit for California’s overall water supply. But the Delta’s levees are vulnerable to failure due to floods, earthquakes and rising sea levels brought about by climate change. A widespread failure could imperil the state’s water supply.

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Sacramento-San Joaquin Delta Litigation

For more than 30 years, the Sacramento-San Joaquin Delta has been embroiled in continuing controversy over the struggle to restore the faltering ecosystem while maintaining its role as the hub of the state’s water supply.

Lawsuits and counter lawsuits have been filed, while environmentalists and water users continue to clash over  the amount of water that can be safely exported from the region.

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Sacramento-San Joaquin Delta Proposals

There are multiple proposals for the Sacramento-San Joaquin Delta underway, though a decision on the future of the Delta is still far from a foregone conclusion.

Unlike past planning efforts that focused primarily on water resource issues and the ecosystem, some current efforts to revitalize the Sacramento-San Joaquin Delta include:

  • land use planning
  • recreation
  • flood management and energy
  • rail and transportation infrastructure

How— or if—all these competing demands can be accommodated is an open question.

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Sacramento-San Joaquin Delta Water Distribution

The majority of people, farms and businesses in California depend on water transported through the Sacramento-San Joaquin Delta.

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Aquapedia background February 11, 2014 California Water Map Layperson's Guide to California Water

Safe Drinking Water Act

The federal Safe Drinking Water Act sets standards for drinking water quality in the United States.

Launched in 1974 and administered by the U.S. Environmental Protection Agency, the Safe Drinking Water Act oversees states, communities, and water suppliers who implement the drinking water standards at the local level.

The act’s regulations apply to every public water system in the United States but do not include private wells serving less than 25 people.

According to the EPA, there are more than 160,000 public water systems in the United States.

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Safe Yield

Landowners in California are entitled to pump and use a reasonable amount of groundwater from a basin underlying their land. When there is insufficient water to meet demand, property owners are expected to extract the safe yield—the rate at which groundwater can be withdrawn without causing long-term decline of water levels.

If the amount of groundwater withdrawn exceeds the safe yield amounts, the well can go dry.

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Salination

Process by which salts accumulate in soil.

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Salinity

Excess salinity poses a growing threat to food production, drinking water quality and public health. Salts increase the cost of urban drinking water and wastewater treatment, which are paid for by residents and businesses. Increasing salinity is likely the largest long-term chronic water quality impairment to surface and groundwater in California’s Central Valley.

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Salton Sea

As part of the historic Colorado River Delta, the Salton Sea regularly filled and dried for thousands of years due to its elevation of 237 feet below sea level.

The most recent version of the Salton Sea was formed in 1905 when the Colorado River broke through a series of dikes and flooded the seabed for two years, creating California’s largest inland body of water. The Salton Sea, which is saltier than the Pacific Ocean, includes 130 miles of shoreline and is larger than Lake Tahoe. 

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San Felipe Division

California’s central coast is home to the San Felipe Division of the federal Central Valley Project. Authorized in the 1960s and completed in 1988, San Felipe Division includes a 5.3-mile-long tunnel (the Pacheco Tunnel), pumping plant and other conduits.

It transports water west from the Central Valley’s San Luis Reservoir near Los Banos to supply Santa Clara and the high-tech Santa Clara Valley as well as parts of Santa Cruz, Monterey and San Benito counties.

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San Francisco Bay

San Francisco Bay and the inter-connected Sacramento-San Joaquin Delta form the largest estuary on the Pacific West Coast.

The estuary is shaped by water flows from two directions.

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San Joaquin River and San Joaquin River Restoration Program

San Joaquin RiverFlowing 366 miles from the Sierra Nevada to Suisun Bay, the San Joaquin River provides irrigation water to thousands of acres of San Joaquin Valley farms and drinking water to some of the valley’s cities. It also is the focal point for one of the nation’s most ambitious river restoration projects to revive salmon populations.

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San Joaquin Valley

Located in the middle of California, the San Joaquin Valley is bracketed on both sides by mountain ranges. Long and flat, the valley’s hot, dry summers are followed by cool, foggy winters that make it one of the most productive agricultural regions in the world.

The valley stretches from across mid-California between coastal ranges in west and the Sierras on the east. The region includes large cities such as Fresno and Bakersfield, national parks such as Yosemite and Kings, millions of people, and fertile farmland.

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San Luis Drain

The San Luis Drain centers on the controversial idea of funneling agriculture drainage water for discharge in the Sacramento-San Joaquin Delta.

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Aquapedia background February 11, 2014 Dams Layperson's Guide to the Central Valley Project Layperson's Guide to the State Water Project

San Luis Reservoir

The San Luis Reservoir is the nation’s largest off-stream reservoir, serving as a key water facility for both the State Water Project (SWP) and the federal Central Valley Project (CVP).

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Santa Ana River

Southern California’s Santa Ana River is the largest watershed drain­age south of the Sierra and is located largely in a highly urbanized, highly regulated setting.

At about 100 miles long and with more than 50 tributaries, the Santa Ana spans parts of San Bernardino, Riverside and Orange counties as it drains 2,840 square miles of land.

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Saturated Zone

Area below the water table in which the soil is completely saturated with groundwater.

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Anne J. Schneider

Anne J. Schneider (1947-2010) is acknowledged as one of the first women to become well-known and well-respected in the field of California and Western water law. “Anne was an amazing person — an accomplished college athlete, mountain climber, skier, marathon runner, velodrome and long-distance cyclist; a devoted mother; a dedicated conservationist,” said Justice Ronald B. Robie in the Inaugural Anne J. Schneider Memorial Lecture in May 2012.

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Seawater Intrusion

Seawater intrusion can harm groundwater quality in a variety of places, both coastal and inland, throughout California.

Along the coast, seawater intrusion into aquifers is connected to overdrafting of groundwater. Additionally, in the interior, groundwater pumping can draw up salty water from ancient seawater isolated in subsurface sediments.

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Selenium

Element that naturally occurs in soils and bioaccumulates in the food chain.

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Septic Systems

In rural areas with widely dispersed houses, reliance upon a centralized sewer system is not practical compared to individual wastewater treatment methods. These on-site management facilities – or septic systems – are more commonplace given their simpler structure, efficiency and easy maintenance.

  • Read California's Septic System Guidelines
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Aquapedia background August 30, 2016 Layperson's Guide to Flood Management Dams

Seven Oaks Dam

Image shows Seven Oaks Dam in the San Bernardino Mountains. Completed in 1999, the Seven Oaks Dam is a 550-feet-high earthen dam on the Santa Ana River.

Its construction at the base of the San Bernardino Mountains was a major component of the Santa Ana River Mainstem Project, costing $464 million and meant to protect the more than 2 million citizens of Orange, Riverside and San Bernardino counties from flooding. To accomplish this, the dam releases only 7,000 cubic feet per second (cfs) of the 85,000 cfs flowing into it, giving it 350-year flood protection. The rest of this flood control project consisted of raising the already existing Prado Dam downstream and building additional channels.

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  • Layperson's Guide to Flood Management
Aquapedia background February 11, 2014 Dams Layperson's Guide to the Central Valley Project California Water Map

Shasta Dam

Image shows Shasta Dam from a distance, with the reservoir largely filled.Shasta Dam forms California’s largest storage reservoir, Shasta Lake, which can hold about 4.5 million acre-feet.

As the keystone of the federal Central Valley Project, Shasta stands among the world’s largest dams. Construction on the dam began in 1938 and was completed in 1945, with flood control as the highest priority.

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Aquapedia background February 11, 2014 California Water Map Layperson's Guide to California Water

Sierra Nevada

The Sierra NevadaStretching 450 miles long and up to 50 miles wide, the Sierra Nevada makes up more than a quarter of California’s land area and forms its largest watersheds, providing more than half of the state’s developed water supply to residents, agriculture and other businesses.*

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Silverwood Lake

A part of the State Water Project, Silverwood Lake is in the San Bernardino Mountains in Southern California. The reservoir stores water for Inland Empire cities such as San Bernardino and Riverside. The water is conveyed from the A.D. Edmonston Pumping Plant via the East Branch Aqueduct.

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Sinkholes

Sinkholes are caused by erosion of rocks beneath soil’s surface. Groundwater dissolves soft rocks such as gypsum, salt and limestone, leaving gaps in the originally solid structure. This is exacerbated when water is acidic from contact with carbon dioxide or acid rain. Even humidity can play a major role in destabilizing water underground. 

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Bernice Frederic “B.F.” “Bernie” Sisk

Bernice Frederic “B.F.” “Bernie” Sisk (1910-1995) represented the San Joaquin Valley in the U.S. Congress for nearly a quarter of a century from 1955-1978.

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Sites Reservoir

Location for the proposed Sites ReservoirThe proposed Sites Reservoir would be an off-river storage basin on the west side of the Sacramento Valley, about 78 miles northwest of Sacramento. It would capture stormwater flows from the Sacramento River for release in dry years for fish and wildlife, farms, communities and businesses.

The water would be held in a 14,000-acre basin of grasslands surrounded by the rolling eastern foothills of the Coast Range. Known as Antelope Valley, the sparsely populated area in Glenn and Colusa counties is used for livestock grazing.

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Robert A. Skinner

Robert A. Skinner (1895-1986) was the Metropolitan Water District of Southern California general manager from 1962-1967. An engineer, he was instrumental in negotiating the district’s contract with the California Department of Water Resources for delivery of water from Northern California. Both Lake Skinner and a treatment plant in southwestern Riverside County were named in his honor.

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Skinner Fish Facility

The John E. Skinner Delta Fish Protective Facility east of San Francisco Bay is a State Water Project facility that works to protect fish in the Sacramento-San Joaquin Delta.

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Sloughs

Sloughs (pronounced “slews”) are shallow lakes or swamps. Generally they serve as backwaters – or a stagnant part of a river – and are consequently located at edges of rivers where a stream or other canal once flowed. 

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Lester A. Snow

Lester SnowLester A. Snow, the mastermind behind countless water resources management projects, has been involved in water issues in two states, both the public and private sectors and on regional, state and federal levels of government.

In a timeline of his career, Snow served from 1988-1995 as the general manager of the San Diego County Water Authority after leaving the Arizona Department of Water Resources. From 1995-1999, he was the executive director of the CALFED Bay-Delta Program, which included a team of both federal and state agencies.

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Springs

Springs are where groundwater becomes surface water, acting as openings where subsurface water can discharge onto the ground or directly into other water bodies. They can also be considered the consequence of an overflowing aquifer. As a result, springs often serve as headwaters to streams.

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South Bay Aqueduct

The South Bay Aqueduct, the first conveyance facility built for the State Water Project, supplies water to Alameda and Santa Clara counties.

To do so, the South Bay Aqueduct relies on 40 miles of pipes and canals to transport the water from the Sacramento-San Joaquin Delta.

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Stanislaus River

The Stanislaus River empties into the San Joaquin River from the east along with the Merced and Tuolumne rivers. Although some agricultural drainage flows into these rivers in their lower reaches, the water quality is relatively good in each of the three tributaries.

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State Liability, Flood Protection and the Paterno Decision

Liability for levee failure in California took a new turn after a court ruling found the state liable for hundreds of millions of dollars from the 1986 Linda Levee collapse in Yuba County. The levee failure killed two people and destroyed or damaged about 3,000 homes.

The collapse also had long-term legal ramifications.

The Paterno Decision

California’s Supreme Court found that, “when a public entity operates a flood management system built by someone else, it accepts liability as if it had planned and built the system itself.”

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Aquapedia background February 11, 2014 California Water Map Layperson's Guide to the State Water Project

State Water Project

The State Water Project is an aquatic lifeline for California because of its vital role in bringing water to cities and farms. Without it, California would never have developed into the economic powerhouse it is.

The Project diverts water from the Feather River to the Central Valley, South Bay Area and Southern California. Its key feature is the 444-mile-long California Aqueduct seen along Interstate 5.

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Ron Stork

Ron Stork, the award-winning policy director of the Friends of the River, joined the statewide California river conservation group in 1987 as its associate conservation director. Previously he was executive director of the Merced Canyon Committee, where he directed the successful effort to obtain the National Wild and Scenic River designation for the Merced River.

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Stormwater

For all the benefits of precipitation, stormwater also brings with it many challenges.

In urban areas, after long dry periods rainwater runoff can contain heavy accumulations of pollutants that have built up over time. For example, a rainbow like shine on a roadway puddle can indicate the presence of oil or gasoline. Stormwater does not go into the sewer. Instead, pollutants can be flushed into waterways with detrimental effects on the environment and water quality.

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Subsidence

Sinking of land(s) due to compaction, oxidation of peat soils, and/or wind erosion, can occur when groundwater is overdrafted.

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Subsurface Drainage

System of underground pipes to remove excess water accumulating below the soil surface that will not naturally percolate out of the root zone.

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Rita Schmidt Sudman

Rita Schmidt Sudman, who led the Water Education Foundation as executive director for more than 30 years, is widely recognized for her work since the 1980s as a journalist and communicator who developed programs to foster public understanding of water issues and for her work with stakeholders to find solutions. A former radio and television reporter and producer, she oversaw the development of print and digital publications, public television programs, poster maps, tours, press briefings and a school program.

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Aquapedia background February 11, 2014 Sacramento-San Joaquin Delta Map Layperson's Guide to the Delta

Suisun Marsh

Suisun MarshSuisun Marsh is where fresh water from the Sacramento-San Joaquin Delta mixes with salt water from San Francisco Bay. The 116,000-acre marsh is the largest contiguous brackish-water wetland in California and perhaps the entire western coast of North America, providing food and habitat for thousands of migratory birds on the Pacific Flyway and many species of plants, fish and wildlife.

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Surface Water

The story of California’s surface water— water that remains on the earth’s surface, in rivers, streams, lakes, reservoirs or oceans—is one that reflects the state’s geographic complexity.

About 75 percent of California’s surface water supply originates in the northern third of the state, but around 80 percent of water demand occurs in the southern two-thirds of the state. And the demand for water is highest during the dry summer months when there is little natural precipitation or snowmelt.

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Surface Water Treatment

A tremendous amount of time and technology is expended to make surface water safe to drink. Surface water undergoes many processes before it reaches a consumer’s tap.

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Aquapedia background May 17, 2016 Layperson's Guide to Groundwater California Groundwater Map

Sustainable Groundwater Management Act (SGMA)

A man watches as a groundwater pump pours water onto a field in Northern California.A new era of groundwater management began in 2014 with the passage of the Sustainable Groundwater Management Act (SGMA), which aims for local and regional agencies to develop and implement sustainable groundwater management plans with the state as the backstop.

SGMA defines “sustainable groundwater management” as the “management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results.”

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Sustainability

People fish along the McCloud RiverSustainability is defined as that which “meets the needs of the present without compromising the ability of future generations to meet their own needs.” In California, several efforts have been undertaken in recent years to address the sustainability and resilience of the state’s vital water resources.

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T

Overview February 11, 2014

T

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Aquapedia background February 11, 2014 Lakes Unwelcome Visitors Layperson's Guide to Climate Change and Water Resources

Lake Tahoe

Lake Tahoe is one of the world’s most beautiful yet vulnerable lakes. Renowned for its remarkable clarity, Tahoe straddles the Nevada-California border, stretching 22 miles long and 12 miles wide in a granitic bowl high in the Sierra Nevada.

Tahoe sits 6,225 feet above sea level. Its deepest point is 1,645 feet, making it the second-deepest lake in the nation, after Oregon’s Crater Lake, and the tenth deepest in the world.

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Tailwater

Excess surface water from land under cultivation, or water below a dam or hydropower development.

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John R. Teerink

John R. Teerink (1921-1992) was the director of the California Department of Water Resources (DWR) from 1973-1975 during Governor Ronald Reagan’s administration.He had various lead roles in the implementation of the State Water Project during his 29-year career at DWR. He progressed through the ranks as junior engineer, assistant chief engineer and then deputy director until his appointment to head the department.

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Tehama-Colusa and Corning Canals

The Tehama-Colusa and Corning canals receive water from the Red Bluff Diversion Dam.

That water is then used to irrigate the west side of the Sacramento Valley as part of the federal Central Valley Project.

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Tidal Excursions

Mixing of waters caused by daily tidal movements in and out of an estuary.

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Transpiration

Process by which plants release water vapor to the atmosphere through the pores of their leaves.

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Tributaries

A tributary of the Feather River.A tributary is a river or stream that enters a larger body of water, especially a lake or river. The receiving water into which a tributary feeds is called the “mainstem,” and the point where they come together is referred to as the “confluence.”

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Trihalomethanes (THMs)

Trihalomethanes are the most common type of “disinfection byproduct,” which is a substance created from the treatment of water with organic matter.

How They Form

Chlorine is the most popular water disinfectant, used widely since the beginning of the 20th century to kill viruses and microorganisms in water. It has had a major role in significantly reducing global instances of cholera and typhoid given its effectiveness and relatively low cost. 

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Aquapedia background February 11, 2014 Dams Shasta Dam

Trinity Dam and Trinity River

Though seemingly a long-way from California’s Central Valley, the Trinity Dam helps supply irrigation water for Valley farmers and for hydropower production.

Constructed in the far northwest of California in the 1950s, Trinity Dam and Lewiston Dam, just downstream, increased the storage capacity of the federal Central Valley Project by more than 2.5 million acre-feet.

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Truckee River

From it headwaters high in California’s Sierra Nevada, the Truckee River flows into and through Lake Tahoe, continuing down the Truckee River canyon to the Reno metropolitan area and then across miles of Nevada high desert before flowing into Pyramid Lake, 40 miles northeast of Reno.

The river’s 145-mile course takes it from alpine forests to high desert sagebrush. (The portion of the Truckee that begins in California in the Sierra Nevada and flows into Lake Tahoe is called the Upper Truckee River.)

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Aquapedia background February 11, 2014 California Water Map Layperson's Guide to Groundwater

Tulare Lake Basin

Image shows flooded crop fields in Tulare Lake Basin in 2023Until the early 1900s, Central California’s Tulare Lake appeared every winter as the southernmost rivers flowing out of the Sierra Nevada filled the dry lakebed with rainfall and melted snow.

In the spring, the shallow lake near Visalia could cover as much as 790 square miles or four times the surface area of Lake Tahoe. However, by the end of the hot San Joaquin Valley summer, the giant lake – once the largest freshwater body west of the Mississippi River – could disappear primarily due to evaporation.

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Tuolumne River

The Tuolumne River is one of the major tributaries draining the western Sierra Nevada.

Beginning high in the mountains of Yosemite at 13,000 feet, the Tuolumne River forms at Mt. Lyell, flows through Tuolumne Meadows, and cascades through canyons including the Grand Canyon of the Tuolumne , as it descends 150 miles into the San Joaquin Valley. There, the Tuolumne empties into the San Joaquin River. The water helps irrigate the agriculturally-rich region, particularly Stanislaus County. The dam at Don Pedro Reservoir near Turlock is also used to generate electricity.

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U

Overview February 11, 2014

U

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Aquapedia background August 15, 2016

Unsaturated Zone

Subsurface zone, usually starting at the land surface and ending at the water table that includes both water and air in spaces between rocks.

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Aquapedia background February 11, 2014 Layperson's Guide to Water Conservation

Urban Conservation

Despite droughts, recession and natural disasters, California’s urban population continues to grow.

This population growth means increasing demand for water by urban areas—home to most of California’s population [see also Agricultural Conservation]. As of 2021, three of the nation’s 10 most populated cities are in California.

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V

Overview January 2, 2016

V

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Henry J. Vaux Jr.

Henry J. Vaux Jr. is the professor of resource economics, emeritus, of the University of California, Berkeley, and the University of California, Riverside.

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Volatilization

Process by which a substance is passed off as vapor or through evaporation.

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W

Overview February 11, 2014

W

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Hiram W. Wadsworth

Hiram W. Wadsworth (1862-1939) is known as the father of Metropolitan Water District of Southern California. As the mayor of Pasadena, he called for a regional partnership of municipalities to bring water to Southern California. After initiating the Colorado River Aqueduct Association and being elected its president, he directed the campaign from 1924-1929 that led to the establishment of the district. The pumping plant at Diamond Valley Lake, located 90 miles southeast of Los Angeles in Riverside County, was named the Hiram W. Wadsworth Pumping/Hydro-generating Facility in his honor.

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Judge Wanger Rulings

Federal Judge Oliver Wanger overturned a federal scientific study that aimed to protect Delta smelt in the Sacramento-San Joaquin Delta.

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William E. “Bill” Warne

William E. “Bill” Warne (1905-1996) had a career for the record books that prominently featured water issues at state, federal and international levels.

He served under Governor Edmund G. “Pat” Brown as the second director of the state Department of Water Resources (DWR) from 1961-1967 along with also being the first Resources Agency secretary from 1961-1963 at the beginning of the construction of the California State Water Project.

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Aquapedia background February 11, 2014 Layperson's Guide to California Wastewater

Wastewater Treatment Process in California

Wastewater management in California centers on the collection, conveyance, treatment, reuse and disposal of wastewater. This process is conducted largely by public agencies, though there are also private systems in places where a publicly owned treatment plant is not feasible.

In California, wastewater treatment takes place through 100,000 miles of sanitary sewer lines and at more than 900 wastewater treatment plants that manage the roughly 4 billion gallons of wastewater generated in the state each day.

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Aquapedia background February 11, 2014 Layperson's Guide to Water Conservation Water Conservation Tips Up Close and Personal: Water Use at Home

Water Conservation

Water conservation has become a way of life throughout the West with a growing recognition that water supply is not unlimited.

Drought is the most common motivator of increased water conservation. However, the gradual drying of the West due to climate change means the amount of fresh water available for drinking, irrigation, industry and other uses must be used as efficiently as possible.

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Water Diversions

Withdrawal of water from a water body, some of which might be returned downstream after use.

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Aquapedia background February 11, 2014 Layperson's Guide to Water Marketing

Water Marketing

Water marketing is the transfer or sale of water or water rights from one user to another, typically from an agricultural to an urban water agency, often without investing in new infrastructure

Most exchanges involve a transfer of the resource itself, not a transfer of the right to use the water.

Reallocating the available water on a supply-and-demand basis is viewed by proponents as the best financial, political and environmental means of accommodating an increase in population.

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Water Master

Individual or committee charged with overall management of a groundwater basin.

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Aquapedia background February 11, 2014 Layperson's Guide to California Water California Water Map

Water Quality

California’s nearly 40 million residents all depend on clean water to thrive, as do the fish and wildlife and industries such as agriculture, food processing and electronics that help power the world’s fourth-largest economy.

Rivers and other surface waters, however, can carry a host of pollutants, both natural and manufactured, that can contaminate drinking water, harm wildlife and livestock and damage crops.

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Water Recycling and Title 22

Cambria Sustainable Water Facility, which recycles wastewater into an eventual drinking-water source. Title 22 of California’s Code of Regulations refers to state guidelines for how treated and recycled water is discharged and used.

State discharge standards for recycled water and its reuse are regulated by the 1969 Porter-Cologne Water Quality Control Act and the State Water Resources Control Board’s 2019 Water Recycling Policy.

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Aquapedia background February 11, 2014 Layperson's Guide to Water Rights Law

Water Rights in California

California’s growth has closely paralleled an evolving and complex system of water rights.

After California became a state in 1850, it followed the practice of Eastern states and adopted riparian rights based on ownership of land bordering a waterway. The riparian property owner has the right to use that water, a right that cannot be transferred apart from the land.

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Aquapedia background February 4, 2014

Water Rights Terms

Adjudicate -To determine rights by a lawsuit in court.

Appropriative Right – A right based on physical control of water and since 1914 in relation to surface water, a state-issued permit or license for its beneficial use. Appropriative water rights in California are divided into pre-1914 and post-1914 rights, depending on whether they were initiated after the December 19, 1914 effective date of the Water Commission Act of 1913. Post-1914 rights can only be initiated by filing an application and obtaining a permit from the state. The program is now administered by the State Water Resources Control Board. 

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Aquapedia background February 11, 2014 California Water Map Layperson's Guide to California Water

Water Supply in California

SnowmeltCalifornia’s “Mediterranean” climate, characterized by warm, dry summers and mild winters, is considered one of its great attractions, but it also can be unpredictable with flooding followed by drought and few years of “normal” precipitation.  [See also Hydrologic Cycle].

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Aquapedia background February 11, 2014

Water Treatment

Finding and maintaining a clean water supply for drinking and other uses has been a constant challenge throughout human history.

Today, significant technological developments in water treatment, including monitoring and assessment, help ensure a drinking water supply of high quality in California and the West.

The source of water and its initial condition prior to being treated usually determines the water treatment process. [See also Water Recycling.]

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Aquapedia background February 6, 2017

Water Use Efficiency

The message is oft-repeated that water must be conserved and used as wisely as possible.

The California Water Code calls water use efficiency “the efficient management of water resources for beneficial uses, preventing waste, or accomplishing additional benefits with the same amount of water.”

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Water Year

California’s water year begins on October 1st, the beginning of the rainy season, and ends on September 30th of the following year.

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Aquapedia background February 11, 2014 California Water Map Layperson's Guide to California Water

Watershed

A watershed is the land area that drains snowmelt and rain into a network of lakes, streams, rivers and other waterways. It typically is identified by the largest draining watercourse within the system. In California, for example, the Sacramento River Basin is the state’s largest watershed.

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Weather

The atmospheric condition at any given time or place, measured by wind, temperature, humidity, atmospheric pressure, cloudiness and precipitation. Weather changes from hour to hour, day to day, and season to season. Climate in a narrow sense is usually defined as the average weather, during a period of time ranging from months to thousands or millions of years.

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Aquapedia background February 11, 2014

West Branch Aqueduct

The West Branch Aqueduct supplies water for Los Angeles and other Southern California cities.

The West Branch is one of two State Water Project aqueducts serving Southern California.

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Aquapedia background February 11, 2014 Sacramento-San Joaquin Delta Map Layperson's Guide to the Delta

Wetlands

Sacramento National Wildlife RefugeWetlands are among the world’s most important and hardest-working ecosystems, rivaling rainforests and coral reefs in productivity. 

They produce high oxygen levels, filter water pollutants, sequester carbon, reduce flooding and erosion and recharge groundwater.

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Aquapedia background February 14, 2014

Frank Elwin “F.E.” Weymouth

Frank Elwin “F.E.” Weymouth (1874-1941) was Metropolitan Water District of Southern California’s first general manager and chief engineer, serving from 1929-1941. The Colorado River Aqueduct and initial distribution system were constructed during his tenure. Metropolitan’s first treatment plant at La Verne in Los Angeles County was named the F.E. Weymouth Treatment Plant in his honor.

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Aquapedia background August 30, 2016

Whiskeytown Lake

Whiskeytown Lake, a major reservoir in the foothills of the Klamath Mountains nine miles west of Redding, was built at the site of one of Shasta County’s first Gold Rush communities. Whiskeytown, originally called Whiskey Creek Diggings, was founded in 1849 and named in reference to a whiskey barrel rolling off a citizen’s pack mule; it may also refer to miners drinking a barrel per day. 

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X

Overview September 8, 2016

X

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Xeriscaping

From the Greek “xeros” and Middle Dutch “scap,” xeriscape was coined in 1978 and literally translates to “dry scene.”  Xeriscaping, by extension, is making an environment which can tolerate dryness. This involves installing drought-resistant and slow-growing plants to reduce water use.

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Y

Overview February 11, 2014

Y

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Aquapedia background February 11, 2014 Layperson's Guide to Flood Management

Yolo Bypass

Yolo Bypass occupies a historic floodplain between Davis and Sacramento, California. The Yolo Bypass is part of a larger engineered system developed on the Sacramento River to provide bypass flood areas, which act as catch basins to deter flooding in communities such as Sacramento and West Sacramento.

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Aquapedia background February 11, 2014 The Lower Yuba Accord: From Controversy to Consensus How Volunteer ‘Streamkeepers’ Influence Water Policy Across the West SPOTLIGHT: Putah Creek, Yuba River and environmental water for fish

Yuba Accord and Yuba River

The Yuba Accord is a landmark multi-agency agreement that balances the interests of environmental groups, agriculture, water agencies and hydroelectric operators relying on water from the Yuba River north of Sacramento. A tributary of the Feather River, the Yuba is the fourth-largest river in the Sacramento River watershed.

Pieced together after two decades of lawsuits, the Yuba Accord allows for freshwater flows to support native fish while also providing water for hydropower, transfers and irrigation.

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Z

Overview September 8, 2016

Z

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Aquapedia background September 8, 2016

Zooplankton

Examples of zooplanktonZooplankton, which are floating aquatic microorganisms too small and weak to swim against currents, are are important food sources for many fish species in the Delta such as salmon, sturgeon and Delta smelt.

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