OCWD was created in 1933 by an act of the California Legislature when Orange County was known more for agriculture than as a business and industrial hub.

At that time, it is estimated that Orange County’s groundwater basin provided about 145,000 acre-feet (179 million cubic meters) of water a year, of which 87 percent was used for agriculture. Today, annual water usage has increased to 350,000 acre-feet (432 million cubic meters) a year, but less than two percent is used for agriculture. The groundwater basin has been able to meet this tremendous increase in water demand because of OCWD’s prudent investment in capital facilities and innovative groundwater management programs.

OCWD’s record is a testament to its commitment to provide Orange County with a reliable supply of high quality water at the lowest reasonable cost in an environmentally responsible manner. Its board of directors and staff take great pride in the fact that OCWD is recognized worldwide for its leadership and innovation in groundwater management, and for projects like the Groundwater Replenishment System and its predecessor Water Factory 21. That leadership will prove important to Orange County as the demand increases statewide for water resources, capital funding and water rights.

Below is a timeline which features important milestones in the District’s more than 80-year history. For additional information, please read the District Act (PDF). For an in-depth look into its tradition of innovation, download A History of Orange County Water District (PDF format, 7,85 mb). 

  • Pre-1700s

    Native Americans were good stewards of the environment. They often settled close to flowing water.

    Prior to European contact, the Native Americans who occupied today’s Orange County lived lightly on the land. Communities, both on the coastline and inland—like the Acjachemen, Payómkawichum and Tongva tribes—worked with seasonal cycles and consumed available flora and fauna. Water sources, such as rainfall, as well as lakes, wetlands, rivers, and streams, met their water needs.

  • 1769-1875

    Californians have been arguing over who has the rights to water since the days of the early settlers.

    As early as 1769, the Spanish diverted water to supply missions, towns and ranches. Disputes over water rights among settlers began soon after. By 1810, laws were enacted to decide who had the right to use various water sources. The California Gold Rush, in the mid-1800s, attracted fortune seekers from all over the world. Local communities throughout California formed municipalities and water departments to meet the water demands of this growing population.  

  • Late 1800s

    Water management was difficult for the pioneers of early Orange County. In response, different agencies began to form.

    The first water district created in the Orange County area was the Serrano Irrigation District in 1876. Landowners north and south of the Santa Ana River continued to fight over water rights as they had done since the river was first used for irrigation in 1810. An 1880 court decision mandated that money must be devoted to the proper development and use of the main water supply. Later, in 1889, the county of Orange was formally established

  • Early 1900s

    Southern California was booming, but most freshwater sources were located in other parts of the state.

    By 1920, Orange County had nine incorporated cities and a rapidly growing population. That same year, the U.S. Geological Survey proposed a statewide plan to transport and store water. In 1928, the Metropolitan Water District of Southern California (MWD) was created to bring water into the region from the Colorado River, and later from Northern California. In 1931, the California State Water Plan became the first comprehensive outline for the use of water resources statewide.

  • 1933

    The Orange County Water District was founded to protect and manage the Orange County Groundwater Basin.

    A significant drought lasted from 1928–1934. During that time, the Orange County Groundwater Basin was overpumped due to the drought and the county’s expanding population. To make sure this didn’t happen again, and to ensure a reliable supply of water, the California State Legislature formed the Orange County Water District (OCWD; the District) on June 14, 1933. 

  • 1938

    An epic flood left a path of destruction, hastening flood control and water conservation.

    The Santa Ana River burst its banks and flooded most of Orange County with up to 4 feet (1.2 meters) of water, damaging more than 68,000 acres (27,520 hectares; 275.2 square kilometers) of land and taking 34 lives. As a flood control measure, the U.S. Army Corps of Engineers (Corps) completed construction of Prado Dam in 1941. More than 50 years later, OCWD reached an agreement with the Corps to capture stormwater behind the dam to use as a supply of additional water.

  • 1954

    Exploding population growth required more imported water. OCWD began charging users for groundwater.

    In 1949, OCWD purchased imported water from MWD to refill the Orange County Groundwater Basin for the first time. Over the next 10 years, the population of Orange County doubled. In order to purchase larger amounts of imported water, a funding source, in addition to property taxes, was required. In 1954, groundwater users in the District agreed to register their wells and pay a pumping fee called the Replenishment Assessment (RA) to bring in additional revenue. 

  • 1965

    Fighting seawater intrusion along the coast became critical to keep the ocean from contaminating drinking water.

    As more and more saltwater from the Pacific Ocean began seeping into the Orange County Groundwater Basin, injecting freshwater to stop basin contamination was required. In 1965, OCWD injected imported water into the groundwater basin at the Alamitos Seawater Barrier for the first time. To this day, the barrier helps protect against seawater intrusion along the border of Los Angeles and Orange counties. 

  • 1969

    OCWD expanded its managerial reach and effectiveness. Water rates and basin levels were formalized.

    A stipulated judgment gave OCWD an annual 42,000 acre-foot (13.7 billion U.S. gallons; 51.8 million cubic meters) of adjudicated water rights of Santa Ana River flow. Also, two programs were created to assist OCWD in managing the groundwater basin. The Basin Production Percentage (BPP), which determines how much water will be pumped from the basin each year, and the Basin Equity Assessment (BEA), which is a surcharge for exceeding the BPP pumping limits, were instituted.

  • 1975

    Recycling and purifying wastewater became a reality in Orange County.

    As imported water supplies became less available, another source of water was needed to fight seawater intrusion. In April 1975, OCWD unveiled Water Factory 21 (WF 21). This facility took treated wastewater from the Orange County Sanitation District (OCSD), blended it with deep well water and injected it into the basin at the Talbert Seawater Barrier. In 1977, WF 21 was the first in the world to use reverse osmosis to purify wastewater to drinking water standards. WF 21 received the first permit ever issued for direct injection of unblended purified wastewater into a seawater intrusion barrier in 1991. 

  • 1990s

    In collaboration with the Orange County Sanitation District, OCWD expanded water reuse efforts.

    In the mid-1990s, OCWD needed to expand Water Factory 21 and address continued problems with seawater intrusion. More water was needed to inject into the Talbert Seawater Barrier. At the same time, OCSD faced the challenge of having to build a second ocean outfall pipe to discharge treated wastewater into the Pacific Ocean. Both districts collaborated to build a state-of-the-art advanced water purification facility to resolve these challenges. The project took 13 years and $481 million to complete. 

  • 2008

    GWRS: The world’s largest advanced water purification plant to supplement drinking water supplies began operation.

    OCWD and OCSD partnered and constructed the Groundwater Replenishment System (GWRS), a 70 million U.S. gallon (265,000 cubic meters) per day advanced water purification facility for potable reuse, which began operating in January 2008. Water from this plant prevents seawater intrusion and replenishes the Orange County Groundwater Basin to supplement drinking water supplies.  

  • 2009

    New OCWD Laboratory Opened.

    The Advanced Water Quality Assurance Laboratory opened to handle over 400,000 analyses of nearly 20,000 water samples each year. It replaced a 35-year-old building and trailers that OCWD had outgrown.

    In 2018, it was renamed the Philip L. Anthony Water Quality Laboratory honoring the longest-serving board member and champion of building the lab.

  • 2015

    Increasing the GWRS output capacity to serve future needs.

    The GWRS was further expanded to produce an additional 30 million U.S. gallons (113,600 cubic meters) per day and now produces 100 million U.S. gallons (nearly 379,000 cubic meters) per day. That is enough water for about 850,000 people. This $143 million initial expansion of the GWRS created new water supplies to serve north and central Orange County. In addition, the expansion further reduced the amount of wastewater discharged into the Pacific Ocean, helping to preserve Orange County’s vibrant coast.

  • 2016

    Children's Water Education Festival celebrates 20 years of environmental education.
    The nation’s largest water education festival, the Children’s Water Education Festival, is a free field trip for Orange County’s third, fourth and fifth grade students to educate them about local water issues and help them understand how they can protect water supplies and the environment. Since inception 20 years ago, the Festival has educated more than 135,000 students. 

  • 2017

    Bottling advanced purified water for the first time in the Western Hemisphere.

    OCWD, with the Orange County Sanitation District, was the first to bottle advanced purified water in the Western Hemisphere. With it, the two agencies started a bottled water tour to educate the greater California public that advanced purified water is clean, reliable and tastes good. Tasting advanced purified water and learning about the process are major factors in gaining the public's approval for future water reuse projects.

  • 2018

    GWRS sets Guinness World Records™ title. 

    The Groundwater Replenishment System set the GUINNESS WORLD RECORDS™ title for the most wastewater recycled to drinking water in 24 hours. The official amount was 100,000,008 gallons. The achievement was a collaboration between the Orange County Water District and Orange County Sanitation District. For the 24-hour period leading up to the announcement and during the official declaration, the future of water, the accomplishments of advanced water purification, and the potential for global water reliability became a major focus around the world.

  • 2019

    OCWD Tackled PFAS.


    Orange County Water District’s Philip L. Anthony Water Quality Laboratory was the first public agency laboratory in California to achieve state certification to analyze for per- and polyfluoroalkyl substances (PFAS) in drinking water.


    OCWD launched the nation’s largest pilot program to test various treatment options for PFAS, a family of man-made heat and water-resistant chemicals found in numerous everyday consumer products that have infiltrated groundwater supplies over several decades.