Water recycling could ease shrinking of Colorado River, new report finds
Researchers say they have identified a crucial solution for states to prevent continued strain on the Colorado River basin for their water needs.
Water recycling can significantly lessen the burden on the Colorado River Basin, but just 26% of treated municipal wastewater is reused across the seven states that depend on the overdrawn river, according to an analysis by the University of California Los Angeles released on Wednesday.
In recent years, persistent drought in the West has reduced water levels in the Colorado River, Lake Mead and Lake Powell -- the two largest reservoirs in the country -- to record-low levels. The river is over-allocated by up to 4 million acre-feet a year, said Mark Gold, director of water scarcity solutions at the Natural Resources Defense Council.
As global warming continues, finding ways to conserve the water in the Colorado River Basin will be essential to ensuring enough supply for residents who rely on it, researchers said. Recycling 40% of wastewater could make a "dramatic difference" in water supplies, Noah Garrison, a water researcher at UCLA’s Institute of the Environment and Sustainability and author of the new report, said.
"We’re facing a hotter, drier future, and we need to pursue water recycling aggressively if we’re going to ensure a sustainable, resilient water supply for the Colorado Basin," Garrison said in a statement.
Currently, Arizona and Nevada recycle more than half of their wastewater, the researchers found. But the other Colorado River Basin states -- California, Colorado, Utah, New Mexico and Wyoming -- lag far behind. Colorado recycles less than 3.6% of municipal wastewater, while Wyoming recycles less than 3.3%, and Utah recycles less than 1%, the report found.
"This is a striking divide," Gold said, adding that federal and state intervention will be necessary to increase wastewater reuse on a large scale.
Up to 40 million people in seven U.S. states -- as well as parts of northern Mexico -- rely on the Colorado River for their water needs, according to the U.S. Bureau of Reclamation. More than half of the Colorado River's total annual water flow is being used to irrigate farmland, a study published in Communications Earth & Environment last year found.
The researchers analyzed data from 2022 from publicly owned treatment centers across the river basin that process more than 1 million gallons per day. But there is currently a "data desert," or a lack of basic tracking on wastewater reuse, which has proved to be a significant barrier to increasing wastewater reuse, the hydrology experts said. Researchers were forced to call treatment plants across the seven states individually, in the absence of a consistent reporting system.
No federal standards for wastewater reuse currently exist.
"It’s almost shocking how little information is available on how much water is being recycled or what recycled water is being used for," Garrison said in a statement.
In 2023, the Biden administration reached a landmark deal with states dependent on the Colorado River to conserve water, requiring the three lower basin states -- California, Nevada and Arizona -- to conserve an unprecedented 3 million-acre-feet of water through 2026.
The Bureau of Reclamation is currently negotiating new Colorado River post-2026 operating guidelines.
State reductions can be less difficult with expanded water recycling, which can offset river demands, Gold said.
But widespread water recycling likely cannot be achieved without major federal and state investments, Gold added.
The researchers identified concrete policy recommendations for both the federal government and basin states. They have called on the U.S. Environmental Protection Agency to develop model state reuse ordinances, work with states to set reuse targets and create standardized reporting protocols for wastewater treatment facilities.
"Water reuse won’t solve the Colorado River crisis alone," Garrison said. "But it’s one of the few solutions available today that can be rapidly scaled and sustained over the long-term."
