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.

1880 First flood control plan for the Sacramento Valley developed by State Engineer William Hammond Hall.

1884 Federal Circuit Court decision in Woodruff v. North Bloomfield requires termination of hydraulic mining debris discharges into California rivers.

1886 California Supreme Court decision in Lux v. Haggin reaffirms legal preeminence of riparian rights, upheld again 40 years later.

1892 Conservationist John Muir founds Sierra Club.

1901 First California deliveries from the Colorado River made to farmland in the Imperial Valley.

1902 U.S. Bureau of Reclamation established by the Reclamation Act of 1902.

1905 First bond issue for the city of Los Angeles’ Owens Valley project; second bond issue in 1907 approved for actual construction.

Colorado River flooding diverts the river into Imperial Valley, forming the Salton Sea.

1908 City of San Francisco’s filings for Hetch Hetchy project approved.

1911 California State Reclamation Board established.

1913 Los Angeles Aqueduct begins service.

1920 Col. Robert B. Marshall of the U.S. Geological Survey proposes statewide plan for water conveyance and storage.

1922 Colorado River Compact appropriates 7.5 million acre-feet per year to each of the river’s two basins.

1923 Hetch Hetchy Valley flooded to produce water supply for San Francisco despite years of protest by John Muir and other conservationists. East Bay Municipal Utility District formed.

1928 Congress passes Boulder Canyon Act, authorizing construction of Boulder (Hoover) Dam and other Colorado River facilities.

Federal government assumes most costs of the Sacramento Valley Flood Control System with passage of the Rivers and Harbors Act.

California Constitution amended to require that all water use be “reasonable and beneficial.”

St. Francis Dam collapses, flooding the Santa Clarita Valley, killing more than 450 people.

Worst drought of the 20th century begins; ends in 1934, establishing benchmark for water project storage and transfer capacity of all major water projects.

1931 State Water Plan published, outlining utilization of water resources on a statewide basis.

County of Origin Law passed, guaranteeing counties the right to reclaim water from an exporter if it is needed in the area of origin.

1933 Central Valley Project (CVP) Act passed.

1934 Construction starts on All-American Canal in the Imperial Valley (first deliveries in 1941) and on Parker Dam on the Colorado River.

1937 Rivers and Harbors Act authorizes construction of initial CVP features by U.S. Army Corps of Engineers.

1940 MWD of Southern California’s Colorado River Aqueduct completed; first deliveries in 1941.

1944 Mexican-U.S. Treaty guarantees Mexico 1.5 million acre-feet per year from Colorado River.

1951 State authorizes the Feather River Project Act (later to become the State Water Project).

First deliveries from Shasta Dam to the San Joaquin Valley.

1955 Flood in the Sacramento Valley kills 38 people.

1957 California Water Plan published.

1959 Delta Protection Act resolves some issues of legal boundaries, salinity control and water export.

1960 Burns-Porter Act ratified by voters; $1.75 million bond issue to assist statewide water development.

1963 Arizona v. California lawsuit decided by U.S. Supreme Court, allocating 2.8 million acre-feet of Colorado River water per year to Arizona.

1964 Partially completed Oroville Dam helps save Sacramento Valley from flooding.

1966 Construction begins on New Melones Dam on the Stanislaus River after 20 years of controversy over the reservoir’s size and environmental impacts; completed in 1978.

1967 State Legislature creates State Water Resources Control Board to enforce water quality and water rights

1968 Congress authorizes Central Arizona Project to deliver 1.5 million acre-feet of Colorado River water a year to Arizona.

Congress passes Wild and Scenic Rivers Act.

1970 Passage of the National Environmental Quality Act, California Environmental Quality Act  and California Endangered Species Act.

1972 California Legislature passes Wild and Scenic Rivers Act preserving the north coast’s remaining free-flowing rivers from development.

Federal Clean Water Act (CWA) passed.

1973 First SWP deliveries to Southern California.

1974 Congress passes Safe Drinking Water Act.

1978 State Board issues Water Rights Decision 1485 setting Delta water quality standards.

1980 State-designated wild and scenic rivers placed under federal Act’s protection.

1982 Proposition 9, the Peripheral Canal package, overwhelmingly defeated in statewide vote.

Reclamation Reform Act raises from 160 acres to 960 acres the amount of land a farmer can own and still receive low-cost federal water.

1983 California Supreme Court in National Audubon Society v. Superior Court rules that the public trust doctrine applies to Los Angeles’ diversion from tributary streams of Mono Lake.

Dead and deformed waterfowl discovered at Kesterson Reservoir, pointing to problems of selenium-tainted agricultural drainage water.

1986 Ruling by State Court of Appeals (Racanelli Decision) directs State Board to consider all beneficial uses, including instream needs, of Delta water when setting water quality standards.

Passage of Safe Drinking Water and Toxic Enforcement Act (Proposition 65) prohibiting discharge of toxic chemicals into state waters.

Coordinated Operation Agreement for CVP and SWP operations in the Delta signed.

1987 State Board’s Bay-Delta proceedings begin to revise D-1485 water quality standards.

1989 In a separate challenge to Los Angeles’ Mono Basin water rights, an appellate court holds that fish are a public trust resource in California Trout v. State Water Resources Control Board.

MWD and Imperial Irrigation District agree that MWD will pay for agricultural water conservation projects and receive the water conserved.

1991 MOU signed to implement urban water conservation programs.

Inyo County and Los Angeles agree to jointly manage Owens Valley water, ending 19 years of litigation.

West Coast’s first municipal sea water desalination plant opens on Catalina Island.

1992 Congress approves landmark CVP Improvement Act.

1993 Federal court rules in Natural Resource Defense Council v. Patterson that the CVP must conform to state law requiring release of flows for fishery preservation below dams.

Arizona’s CAP declared complete by the federal government.

1994 State Board amends Los Angeles’ water rights licenses to Mono Lake.

Bay-Delta Accord sets interim Delta water quality.

CALFED Bay-Delta Program planning initiated.

1995 State Board adopts new water quality plan for the Delta and begins hearings on water rights.

1997 New Year’s storms cause state’s second most devastating flood of the century.

SWP’s Santa Barbara Aqueduct completed.

1999 Sacramento splittail minnow and spring-run Chinook salmon added to federal endangered species list.

2000 CALFED Record of Decision signed by state and federal agencies.

2001  Klamath Project irrigation water crisis.

2002 Voters approve Proposition 50, a $3.44 billion bond issue to fund improvements in water quality and reliability.

2003 Interior Secretary orders California’s Colorado River allocation limited to 4.4 million acre-feet; water users sign Quantification Settlement Agreement.

Paterno v. State of California ruling by Third Appellate District Court determined the state of California liable for potentially hundreds of millions of dollars because state accepted levee without any measures to ensure it met design standards and then failed in 1986 flood.

SWP contractors, DWR and environmental groups settle lawsuit over the Monterey Amendment.

U.S. Fish and Wildlife Service removes Sacramento splittail from federal ESA list of threatened species.

2004 State Board initiates review of 1995 Water Quality Control Plan.

Congress approves long-awaited legislation to re-authorize CALFED.

2005 Scientific surveys of the Delta and Suisun Marsh reveal ongoing, sweeping population crash of native pelagic fish.

Legislation directs DWR to evaluate the future of the Delta.

2006 Coalition of fishing groups sue DWR, alleging the agency never obtained proper legal authority to take endangered fish while exporting water.

Legal settlement among a coalition of environmental and fishing groups, the U.S. Departments of the Interior and Commerce and the Friant Water Users Authority ending an 18 year legal battle over claims to release water from Friant Dam to maintain a live stream for fish to the Merced River.

2007 SWP pumping operations shut down to protect endangered Delta Smelt (Wanger Decision).

DWR estimates that Delta levees are vulnerable to massive failure if major earthquake occurs.

Seven Colorado River states agree to new drought rules and shortage criteria.

Delta Vision Blue Ribbon Task Force releases plan. Other Delta planning processes continue.

2008 DWR initiates the Bay Delta Conservation Plan (BDCP) EIS/EIR.

Governor declares statewide drought after second dry/critical year.

Public Policy institute of California issues report saying a peripheral canal is best Delta conveyance for meeting co-equal goals of healthy Delta ecosystem and water supply reliability.

State Reclamation Board is renamed Central Valley Flood Protection Board.

2009 U.S. District Judge Oliver Wanger rules federal government did not analyze impact of Delta Smelt protection rules on water exporters. Gov. Schwarzenegger signs a comprehensive water package designed to achieve the co-equal goals.

San Joaquin River Restoration Act passed by Congress.

USGS report finds that about 60 million acre-feet of groundwater has been lost in the San Joaquin Valley since 1961.

2010 Judge Wanger rules the federal government failed to consider impacts to water users when it restricted pumping from Delta to protect Chinook spring-run salmon and other fish.

Final Klamath Basin Restoration Agreement and the Klamath Hydroelectric settlement Agreement were signed. The implementation was contingent on authorizing legislation, funding and environmental review.

2012 Central Valley Flood Protection Plan adopted by state flood board; California becomes the first state in the nation to legislatively recognize the human right to water.

2013 Delta Plan is adopted by the Delta Stewardship Council.

2014 Sustainable Groundwater Management Act (SGMA) is signed into law; California voters approve a $7.5 billion Proposition 1 water bond, which includes $2.7 billion for the Water Storage Investment Program.

2015 Amid deepening drought, Gov. Jerry Brown announces first statewide water conservation mandates aimed at urban areas.

2017 Mandatory evacuations are ordered for more than 180,000 people in Northern California after a spillway collapse at Oroville Dam.

2018 The State Water Board adopts standards to establish instream seasonal unimpaired flows on the San Joaquin, Stanislaus, Tuolumne and Merced rivers as part of the Bay-Delta Water Quality Control Plan.

2019 Gov. Gavin Newsom downsizes his predecessors’ plan for twin Delta tunnels to a single tunnel; Safe and Affordable Drinking Water Fund enacted to provide financial support for communities lacking access to safe drinking water; the seven Colorado River states agree to a set of drought contingency plans that augment the 2007 interim guidelines.

2020 A deal is struck between California, Oregon, PacifiCorp and the Karuk and Yurok tribes to remove four dams on the Klamath River; the COVID-19 pandemic highlights the need for water availability for hand-washing and affordability for people who lost jobs.

2021 Gov. Newsom declares a state of emergency for drought.

2022 Gov. Newsom announces a statewide water-supply strategy for “Adapting to a Hotter, Drier Future” prioritizing actions to capture, recycle, de-salt and conserve more water.

2023 An extremely wet winter brings dramatic end to the drought, and floods more than 90,000 acres of farmland in the Tulare Lake Basin, temporarily bringing back Tulare Lake; to protect beleaguered chinook salmon populations, regulators shut down the commercial fishery and keep it closed for the two subsequent years; work begins to demolish four dams on the Klamath River, including three in California, as part of the nation’s largest dam removal and salmon habitat restoration effort.

2024 As SGMA turns 10, water users begin facing the impacts of stricter groundwater rules, particularly in the San Joaquin Valley; Proposition 4 adds an additional $75 million to the Water Storage Investment Program.

2025 President Donald Trump issues executive order directing federal agencies to “immediately take actions to override existing activities that unduly burden efforts to maximize water deliveries” in California; State Water Board begins hearings on DWR’s water rights petition for the Delta Conveyance Project, which continue into 2026; Gov. Newsom signs Senate Bill 72, which requires DWR to identify 9 million acre-feet of additional water supply by 2040 to offset losses anticipated as the climate continues to warm; State Water Board unveils the California Water Accounting, Tracking and Reporting System (CalWATRS), significantly improving the online availability of California water rights records.

2026 The package of rules guiding operations of the Colorado River, including the 2007 interim guidelines and the 2019 drought contingency plans, expire; the proposed Sites Reservoir gets federal approval to move forward; State Water Board holds hearings on its update to the Bay-Delta Water Quality Control Plan, including its voluntary agreement pathway for water users.