How a Carlsbad desalination plant could help Arizona and Nevada

In early June 2026, federal and regional water agencies signed a memorandum of understanding to explore interstate water exchanges that may use desalinated ocean water. Parties to the agreement include the U.S. Bureau of Reclamation, the San Diego County Water Authority, the Metropolitan Water District of Southern California, the Southern Nevada Water Authority, and Arizona water agencies, which will study legal, operational and funding issues.

The Claude "Bud" Lewis Carlsbad Desalination Plant, which began commercial operations in 2015, can produce more than 50 million gallons of drinking water per day and serves about 400,000 people in the region. On a typical day the plant draws roughly 100 million gallons of seawater and uses energy recovery devices that reduce the plant’s net electricity use; brine is returned to the ocean after dilution.

The MOU is expressly nonbinding and does not alter existing water rights or current contracts; it creates a collaborative process to identify pilot projects, legal pathways and potential federal funding. The signatories noted that further environmental review, governance approvals and legislative actions would be required before any water could be moved across state lines.

If an exchange pilot goes forward, San Diego’s desalinated supply could allow the Water Authority to keep more of its Colorado River allocation in storage, while Arizona and Nevada could receive desalinated water through negotiated arrangements. Nevertheless, the agreement itself does not compel transfers and any implementation will be subject to the results of studies and formal board or legislative approvals. Stakeholders will continue public outreach.