🚰 Desalinated seawater could ease pressure on the Colorado River

• San Diego is negotiating with Arizona and Nevada to sell water from North America's largest desalination plant.
• The agreement could supply roughly 500,000 people with drinking water annually.
• San Diego has reduced its water imports from 95 percent to 10 percent over three decades.

As the Colorado River declines, the states of Arizona and Nevada are looking for new water sources. The solution may be the ocean off the California coast. Both states are negotiating with the San Diego County Water Authority to gain access to fresh water from the desalination plant in Carlsbad, which is the largest in North America.

How the agreement works

No water is physically transported between the states. Instead, it is about exchanging rights to different water sources. Arizona and Nevada would finance a portion of the 56,000 acre-feet of water the desalination plant produces each year. In exchange, the states would gain access to San Diego's share of the Colorado River. The agreement could supply around 500,000 people with water.

John Entsminger, general manager of the Southern Nevada Water Authority, plans to sign an initial agreement together with Arizona's water authority.

San Diego built its own independence

During a drought that ended in 1992, San Diego lost a third of its water allocation. At the time, the city imported nearly all of its water. Over the following three decades, the water authority invested billions of dollars to become self-sufficient. It raised a dam wall to double storage capacity, built the desalination plant, and acquired rights to conserved water from a farming district.

The result is that San Diego reduced its water imports from 95 percent to 10 percent. At the same time, residents of the city have cut their water consumption by nearly 50 percent over the past quarter century. This has given the city a water surplus that can now be sold on.

More projects underway

Nevada and Arizona are also partnering with the Metropolitan Water District of Southern California to build a facility in Los Angeles County. It will be able to treat up to 165,000 acre-feet of wastewater per year, enough for a city of 1.5 million residents. Utah has expressed interest in investing in more desalination plants along the Pacific coast.

In Santa Monica Bay, the Las Virgenes Municipal Water District and the company OceanWell are testing a new technology. Pods the size of school buses are lowered more than 1,200 feet below the ocean surface to desalinate water directly on the seabed. The technology reduces both costs and environmental impact compared with desalination on land.

San Diego also recycles wastewater under the name Pure Water San Diego. The recycled water is already being used by local breweries, including AleSmith Brewing Co., which has used it in a lager called Re:Beer.

Arizona's water consumers have already cut their consumption by nearly a third.

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