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Environment and Natural Resources

Water

California’s water system is complex. This complexity can be seen in how the system is structured—with multiple sources of water that are interconnected in various ways. It is also evident in how the system is financed—using a variety of sources at the local, state, and federal level to meet the needs of urban and agricultural water users and the environment. This web page provides some "quick reference" tables and graphics that illustrate some key elements of California's water system.


On this page:

HISTORY AND MANAGEMENT


Selected Events in State Water Policy History—Timeline

Selected Events in State Water Policy--A Timeline

 

Many Entities Are Involved in Water Management

Responsibilities

Water Supply

Water Quality

Flood Control

State Agencies

Department of Water Resources

X

X

State Water Resources Control Board

X

X

California Public Utilities Commission

X

X

Colorado River Board

X

Delta Stewardship Council

X

X

X

Department of Pesticide Regulation

X

Department of Toxic Substances Control

X

Department of Conservation

X

Office of Environmental Health Hazard Assessment

X

Federal Agencies

Bureau of Reclamation

X

X

Army Corps of Engineers

X

X

Environmental Protection Agency

X

Geological Survey

X

X

Other Entities

Cities and counties

X

X

X

Special districts

X

X

X

Tribal governments

X

X

X

Private water companies

X

For more information, please see our publication California’s Water: An LAO Primer

California's Water System Moves Water, Mainly from North to South

California's Water System Moves Water, Mainly from North to South

For more information, please see our publication Achieving State Goals for the Sacramento-San Joaquin Delta

Types of Water Systems in California

  • Public Water System: Provides water for human consumption and (1) has 15 or more service connections or (2) regularly serves at least 25 individuals daily at least 60 days out of the year. Water quality is generally regulated by the State Water Resources Control Board (SWRCB), although in 29 counties SWRCB has delegated authority to regulate smaller systems with between 15 and 200 connections to county environmental health departments.
  • Community Water System: Public water system that (1) serves at least 15 service connections used by yearlong residents or (2) regularly serves at least 25 yearlong residents. Roughly 2,900 across the state, serving about 39 million people.
  • Noncommunity Water System: Public water system that (1) regularly serves 25 or more of the same persons for more than 6 months but fewer than 12 months per year (referred to as “nontransient”), such as a school, or (2) does not regularly serve at least 25 of the same persons over 6 months of the year (referred to as “transient”), such as a rest stop or campground. Roughly 1,500 nontransient systems and 3,000 transient systems across the state.
  • Tribal Water System: Public water system that is located on tribal land and serves a federally recognized tribe. Regulated under tribal sovereign authority in partnership with the U.S. Environmental Protection Agency, not SWRCB.
  • State Small Water System: Provides water for human consumption with between 5 and 14 service connections and does not regularly serve drinking water to more than an average of 25 individuals daily for more than 60 days out of the year. Water quality is overseen by county health officers. Roughly 1,500 across the state.
  • Domestic Well: Groundwater well used to supply water for the domestic needs of an individual residence or a water system that has no more than four service connections. Water quality not regularly monitored by the state or local governments. At least 350,000 across the state, providing water for between 1.5 million and 2.5 million Californians.

For more information, please see our publication Expanding Access to Safe and Affordable Drinking Water in California—A Status Update.


PRECIPITATION AND WATER USE


California's Precipitation is Highly Variable

California's Precipitation is Highly Variable

 

Water Supply Versus Demand

Water Supply Versus Demand

Use of Water Changes Significantly From Wet to Dry Years

Use of Water Changes Significantly From Wet to Dry Years

For more information, please see our publication California’s Water: An LAO Primer


FLOODS


Exposure to 500-Year Flood by Region

Exposure to 500-Year Flood by Region

 

Illustration of Key Flood Infrastructure Components

Illustration of Key Flood Infrastructure Components

 

For more information, please see our publication Managing Floods in California


GROUNDWATER


Implementation Timeline for Major Sustainable Groundwater Management Act (SGMA) Requirements

Implementation Timeline for Major Sustainable Groundwater Management Act (SGMA) Requirements

STATE BOND FUNDING

Water-Related General Obligation Bonds

1970-2018 (In Millions)

Year

Proposition Number

Title

Amount Authorized

1970

1

Clean Water Bond Law of 1970

$250

1974

2

Clean Water Bond Law of 1974

250

1976

3

California Safe Drinking Water Bond Law of 1976

175

1978

2

Clean Water and Water Conservation Bond Law of 1978

375

1982

4

Lake Tahoe Acquisitions Bond Act

85

1984

2

California Safe Drinking Water Bond Law of 1984

75

1984

28

Clean Water Bond Law of 1984

325

1984

19

Fish and Wildlife Habitat Enhancement of 1984

85

1986

55

California Safe Drinking Water Bond Law of 1986

100

1986

44

Water Conservation and Water Quality Bond Law of 1986

150

1988

8

California Safe Drinking Water Bond Law of 1986

75

1988

70

California Wildlife, Coastal, and Park Land Conservation Act

776

1988

83

Clean Water and Water Reclamation Bond Law of 1988

65

1988

82

Water Conservation Bond Law of 1988

60

1996

204

Safe, Clean Reliable Water Supply Act

995

2000

13

Safe Drinking Water, Clean Water, Watershed Protection, and Flood Protection Act

1,970

2000

12

Safe Neighborhood Parks, Clean Water, Clean Air, and Coastal Protection Bond act of 2000

2,100

2002

40

California Clean Water, Clean Air, Safe Neighborhood Parks, and Coastal Protection Act of 2002

2,600

2002

50

Water Security ,Clean Drinking Water, Coastal and Beach Protection Act of 2002

3,440

2006

1E

Disaster Preparedness and Flood Protection Bond Act of 2006

4,090

2006

84

Safe Drinking Water, Water Quality and Supply, Flood Control, River and Coastal Protection Bond Act of 2006

5,388

2014

1

Water Quality, Supply, and Infrastructure Improvement Act of 2014

7,120a

2018

68

Drought, Water, Parks, Climate, Coastal Protection, and Outdoor Access for All Act of 2018

4,100

Total

$34,649

aProposition 1 also repurposed a total of $425 million from Proposition 84, Proposition 1E, Proposition 50, Proposition 13, Proposition 204, and Proposition 44.

For more information, please see the California Natural Resources Agency's bond accountability webpage.


Last Updated: December 2021