During the hottest days of the year, sun glimmers off of an aqueduct as it moves water from the shrinking Colorado River to millions of residents in the sprawling cities of Southern California. In one of the nation’s most populous regions, many cities import a large portion of their drinking water from faraway rivers through this aqueduct and a network of dams and diversions.

But climate change means a lot less could be available going forward. Over the past two decades, the worst drought in 1,200 years has driven the Colorado River into extreme shortages, forcing officials across the American Southwest to confront hard realities and make tough calls about the future.

This has meant some cities are having to look for new sources of water more isolated from weather swings. And cities dependent on the Colorado River are eyeing water that’s dumped down the drain.

“We really kind of refer to this as our third aqueduct,” says John Bednarski, an interim assistant general manager at the Metropolitan Water District of Southern California — a powerful agency, as the largest wholesale provider of water in the nation and owner of the Colorado River Aqueduct.

The “third aqueduct” Bednarski is referring to is not another man-made appendage stretching to the Colorado River Basin or into Northern California but rather a project that’s designed to stay local — and sustainable: Pure Water Southern California would recycle wastewater, treat it and produce 150 million gallons of water each day, accounting for about 10 percent of the agency’s local water demands, according to Bednarski. “So it’s going to be a major contributor,” he says.

At the same time, the agency has seen new models predicting climate change will reduce stream flows from not only the Colorado River but also sources in Northern California.

“The reality of climate change has really sunk in,” he says. “We’re looking at it now as a reality.”

Other cities are watching too, and for similar reasons.

The L.A. Department of Water and Power is pursuing a similar recycling project. And in 2022, 26 cities and wholesale water providers that pull from the Colorado River wrote a memorandum of understanding committing to focusing on water recycling and reuse. The signatories, including Metropolitan, often point to Las Vegas as a model for recycling wastewater to reduce its total Colorado River use and increase the amount of water available for use. Nevada has long faced scarcity; of all the states, it receives the smallest share of the river: just 1.8 percent of all the water rights.

By treating and reusing nearly all of its indoor water, the Las Vegas water purveyor effectively uses the same water over and over, expanding its supply. Now Las Vegas officials, along with Arizona water managers, are looking to the Pure Water project to further shore up supplies on the Colorado River. Their thinking: If Metropolitan can reduce its Colorado River use, its unused water could flow to Nevada and Arizona, providing a needed boost in an era when there is little to spare. 

In that way, water recycling projects in one area can have consequences across watersheds. 

The Las Vegas water district and agencies in Arizona have made financial investments in the early planning phases of the Pure Water project. Bednarski says his agency plans to release a draft environmental review this year and bring it before a board vote in January 2026. The board will have to weigh the benefits of the recycling project against its significant $8 billion price tag.

Despite the hefty bill, Mark Gold, a director with the Natural Resources Defense Council who sits on Metropolitan’s board, says the project comes with “extraordinary” environmental benefits — namely, increased water security. The drought, he says, “shattered” the myth of unlimited water. But he notes that rates need to be affordable, and he sees a need for federal investment in these projects.

“The days of relying on 60 to 90 percent of our water coming from more than 300 miles away have to end,” he says. “It’s just too vulnerable. That’s the transformation we’re starting to see in Los Angeles, and these same sorts of discussions are occurring elsewhere in the Southwest.”

The program serves two purposes: It stores drinking water for use and buffers the aquifer against contamination from the ocean. When the aquifer is empty, salt water can flow in and pollute it.

Decades ago, the district realized it could not serve all its customers with local supplies while it kept the aquifer full to guard from the sea. With climate change on the horizon, it did not want to stake all of its security on imported water. It needed to find an alternative supply, says Mehul Patel, executive director of operations for the district’s groundwater program. “That’s when we started really investing and investigating the use of highly treated recycled wastewater,” he says. 

The groundwater replenishment system came online in 2008, and the district boasts that it has produced more than 450 billion gallons of water since then. But at the time, Patel acknowledges, it was a hard sell convincing the board and customers that it was needed, safe and worth the cost. 

Then there is the ick factor of recycling sewage. Concerns had torpedoed past projects, and the district worked early to get endorsements from medical professionals that the project would be safe. “That was a big game-changer in terms of getting more public acceptance and not having any public sentiment that would kill the project,” he says. “That was the number-one huge thing.”

But even with public buy-in and the water purification technology available to reclaim effluent to drinking water standards, there are still technical details that have to be worked out. Gold says he still has questions about how agencies dispose of contaminants filtered from the wastewater.

What to do with leftover brine after wastewater is treated “becomes the bigger environmental issue than the public health component and opposition because it’s ‘toilet-to-tap,’” he says.

For years, Metropolitan has been working to engage the public in the process, but the final pitch will not come until next year when the project goes before its board, which will be weighing several costly projects, including a tunnel and reservoir in northern California for its imported water. 

“There’s several really big decisions that our board has to make so it’s going to be a challenging sell,” he said. “But we’re optimistic. … We’re trying to come up with ways to jump start the program — like start smaller and make it scalable.”

And given the project’s regional impact, the agency is also looking for funding on the federal and state level, as well as from Colorado River agencies in Arizona and Nevada “We’re going to push all the buttons and pull all the levers we can to bring in external sources of funding,” he said.

Scrolling image credits: First set of images appears courtesy of the Metropolitan Water District of Southern California. The second and third sets appear courtesy of the Orange County Water District.