With desert cities like Phoenix and Tucson bracing for their allotments of Colorado River water to be slashed dramatically, San Diego County’s water agency could for the first time sell some of its water to other states by drawing on its ample supplies from the nation’s largest desalination plant.
The San Diego County Water Authority’s board unanimously approved an initial agreement last week to consider selling some of its water to Arizona and Nevada, where cities that depend on the over-tapped Colorado River are expected to face substantial cuts in water supplies.
General Manager Dan Denham said the agreement, if approved by other agencies, could clear the way for the first-ever interstate transfers of Colorado River water starting next year.
“It’s just a different way of managing water in the West,” Denham said. “I think it has to happen now, and it has to happen because of the situation on the river.”
The Colorado River provides water for farms, cities and tribal communities across seven states and northern Mexico. Its reservoirs have declined dramatically over the last 25 years as drought compounded by climate change has shrunk the river flow.
Negotiators for the seven states, despite extensive talks, remain at odds on the water cutbacks each should accept to prevent reservoirs from declining further.
Officials at San Diego County Water Authority plan to consider selling water across state lines by letting agencies in Arizona and Nevada purchase some of its Colorado River supplies. The revenue generated, the San Diego County agency says, would be used to reduce costs for its ratepayers.
The agreement — technically a memorandum of understanding — first would need to be approved by the Metropolitan Water District of Southern California, the federal government and agencies in Arizona and Nevada. Then, various water agencies would need to negotiate the details.
The San Diego County Water Authority serves as a wholesaler, delivering water to 22 cities and other agencies that serve 3.3 million people.
The authority is in a position to sell a portion of the region’s water because it has invested heavily in securing additional water supplies from the Claude “Bud” Lewis Carlsbad Desalination Plant, which since 2015 has been drawing in seawater and churning out a portion of the area’s drinking water. The authority secured additional water through a 2003 agriculture-to-urban transfer deal. These and other investments have brought San Diego County plentiful water — though as a result, the region also has some of the most expensive water in the state.
The Water Authority purchases water from the Carlsbad desalination plant under a 30-year agreement. But the plant is currently operating at less than full capacity, Denham said, and its output could be increased to provide a larger share of the region’s water if agencies in other states bought some of the Water Authority’s Colorado River water. Essentially, it’s too expensive to run the plant at full capacity at this time given the availability of other more economical supplies, but out-of-state money could make it worth the agency’s while.
Conservation efforts have also reduced the water needs of many of the cities that the Water Authority serves. And in the next few years, the area will also start recycling wastewater at new facilities, including San Diego’s Pure Water project as well as other recycling projects in Oceanside and eastern San Diego County.
If other states and agencies sign on, Denham said the Water Authority is prepared to sell up to 10,000 acre-feet of water starting next year. That’s nearly 5% of the Las Vegas area’s current water use.
In future years, he said, that could increase to 25,000 acre-feet or more. And with additional investment in upgrades, the Carlsbad desalination plant could be expanded to transform more seawater into drinking water, thereby freeing up additional water to be traded to cities that need it.
“It’s in everyone’s best interest to make this work,” Denham said.
Gov. Gavin Newsom has supported the idea, telling governors of the other six states in a recent letter that California would welcome joint investments in water recycling and desalination.
Denham said Scott Cameron, the Trump administration’s acting head of the U.S. Bureau of Reclamation, has also supported the idea.
The board of the Metropolitan Water District has yet to vote on the proposed agreement.
“I believe these kinds of concepts are what we need to do in regards to thinking about water resources, not from political boundaries, but as a region,” said Shivaji Deshmukh, the district’s general manager.
If the San Diego County Water Authority eventually reaches deals with other agencies, the amount of water sold will be small compared to the gaping water shortfall that is pushing reservoir levels lower along the Colorado River. But Denham said if it works, this approach could be a first step in showing that deals between states can help ease the water shortages.
