Two separate initiatives in Arizona and California detail how local water authorities are responding to federal proposals to reduce Colorado River water deliveries, which are driven by prolonged drought and declining reservoir levels.
Cave Creek, Arizona: Backup Plans for CAP Water
Cave Creek, Arizona, a town of approximately 5,000 residents, relies on the Colorado River for 95% of its water supply via the Central Arizona Project (CAP). The federal government has proposed significant cuts to CAP water deliveries by January 2027.
"Cave Creek officials have developed a short-term backup plan involving water exchanges with the cities of Phoenix, Peoria, and Surprise."
Under this arrangement, those cities will use groundwater, leaving CAP water in the canal for Cave Creek. The town is also planning an interconnect with Phoenix’s water system.
Longer-term solutions under consideration include importing water from the Harquahala aquifer, purchasing water from farms or tribes, wastewater recycling, and desalination. Town officials have noted that the cost of these alternatives presents a challenge. Regional officials are cooperating with the stated goal of protecting the Phoenix area’s economic reputation.
San Diego County: Exchange of Desalinated Water for River Supplies
In California, the San Diego County Water Authority has proposed exchanging its Colorado River water stored in Lake Mead for desalinated water produced in San Diego. This exchange would leave more river water in Lake Mead for other users.
San Diego receives approximately eight inches of rain annually and is at the end of the Colorado River delivery system. Its current water surplus is attributed to water recycling, conservation programs, and the Claude "Bud" Lewis Carlsbad Desalination Plant. The plant, operational since 2015, produces approximately 50 million gallons of potable water per day, supplying 7-10% of the region’s water.
The proposed exchange requires approval from the U.S. Department of the Interior. The Southern Nevada Water Authority, the Central Arizona Project, and other agencies have signed a memorandum of understanding to explore purchasing San Diego’s desalinated water.
Statements- Meena Westford, director of imported water at the San Diego County Water Authority, stated that water managers aim to demonstrate a new way to manage the Colorado River system.
- Patrick McDonough, senior attorney with San Diego Coastkeeper, stated that desalination is energy-intensive and expensive, and that conservation and recycling are more effective.
- John Entsminger, general manager of the Southern Nevada Water Authority, stated that Las Vegas does not need the water this year but is willing to invest in projects that leave water in Lake Mead for the entire system's benefit.
- Desalinated water costs five to ten times more than river water.
- Critics argue the Carlsbad plant’s output represents a small fraction of total Colorado River basin supplies.
- The plant has contributed to higher local water bills.
Background on Regional Water Conditions
The western megadrought has reduced water levels in Lake Mead and Lake Powell, the two largest U.S. reservoirs, threatening hydropower generation at Hoover Dam. The Rocky Mountains experienced their hottest and driest winter on record. Federal forecasts indicate water levels at Hoover Dam could drop low enough to shut down turbines, a condition referred to as "deadpool."
Next Steps
Interstate water transfer rules are expected to be finalized by the end of the year.