The San Diego Story

The Carlsbad Seawater Desalination Project was conceived well before the current drought gripped California. In fact, the historic plant – the largest in the nation – is part of a strategic vision by the San Diego County Water Authority that has its roots in the drought of 1987-92.

Since that time, the Water Authority has become a national leader in developing new water supplies and making the most of every drop through innovative conservation programs and resources. The desalination project is one of the major components of its plan to diversify the region’s water supply portfolio.

Meeting Long-Term Water Needs

A safe, reliable water supply is crucial for the vitality of the San Diego region’s $220 billion economy and quality of life for 3.3 million residents. To maximize the reliability of those supplies, for more than two decades the Water Authority has been executing a long-term strategy to diversify its water sources, make major investments in the region’s water delivery and storage system, and improve water use efficiency.

In 1991, the San Diego region was 95 percent reliant on a single supplier of imported water – the Metropolitan Water District of Southern California. This made the region extremely vulnerable to water supply shortages. That year, an ongoing drought forced MWD to cut deliveries to the San Diego region by 31 percent.

As a result of that crisis, the Water Authority’s Board of Directors approved a strategy to aggressively diversify the region’s water supply portfolio by developing new local and imported water supplies. This strategy already is enhancing regional supply reliability. Today, the Water Authority gets only about half of its water from MWD.

The Water Authority is working with its 24 member agencies to develop local resources such as groundwater, recycled water, seawater desalination, and conservation. By 2020, local water supplies are projected to meet more than a quarter of the region’s water demand.



Total = 578 TAF


Total = 518 TAF

Projected 2020

Total = 537 TAF

Estimated 2035

Total = 632 TAF

TAF = Thousand Acre-Feet

pie_yellowMetropolitan Water District
pie_blueImperial Irrigation District Transfer
pie_redAll American & Coachella Canal Lining
pie_pinkRecycled Water
pie_orangeSeawater Desalination
pie_aquaLocal Surface Water
pie_purplePotable Reuse (Includes conceptual and planned projects)
pie_green     San Luis Rey Water Transfer

Water-use efficiency as a way of life

Conservation has been a key component of the Water Authority’s supply diversification strategy from the start, and urban per capita potable water use in San Diego County declined nearly 40 percent from 1990 to 2015, even before the state imposed emergency water-use targets. The Water Authority works with its member agencies and other partners to offer programs that improve water-use efficiency for residential, commercial and agricultural users, and promote conservation as a way of life.

Water conservation-and-transfer agreements

The Water Authority also has secured new imported water supplies through a historic 45- to 75-year water conservation-and-transfer agreement with the Imperial Irrigation District. The deal, reached in 2003, will provide 200,000 acre-feet annually by 2021. In addition, the Water Authority has a separate 110-year agreement to receive Colorado River water conserved by lining sections of the Coachella and All-American Canals. These projects provide 80,000 acre-feet of water to the region annually. Together, the conservation and transfer agreements are projected to provide about half of the region’s water supply in 2020.

Major capital improvements

The Water Authority also is in the final stages of executing a $2.8 billion Capital Improvement Program to improve regional water delivery and storage capacity. The program comprises dozens of projects, including new reservoirs, pipelines, pump stations and a regional water treatment facility. A cornerstone element of the program was raising San Vicente Dam in East County by 117 feet to provide 152,100 acre-feet of additional local storage. Completed in 2014, it was the largest single increase in water storage in county history.

Advancing potable water reuse & recycling

The Water Authority has been advancing water recycling and reuse by promoting scientific analysis and guidance from technical advisory panels, securing money to study related issues, conducting polling to measure public support, and sponsoring state legislation to speed the adoption of regulations for potable reuse. In 2015, recycled water production in the San Diego region was on par with the supplies derived from local groundwater and surface water combined. And in 2035, projections show that water recycling combined with potable reuse will meet nearly a quarter of the region’s demand.