PHOENIX — Officials in the Southwest are exploring a potential multi-state arrangement that could shift additional Colorado River supplies to Arizona, as San Diego County considers selling some of the river water rights it holds. The offer stems from a surplus generated by San Diego’s coastal desalination plant, and could represent the first large-scale interstate trade of Colorado River rights if the details are finalized and approved.
San Diego’s desalination facility, which removes salt and other minerals from ocean water to produce potable water, has produced more water than the county currently needs. That excess capacity is the foundation for the proposed deal: by relying more on desalinated seawater and drawing less from the Colorado River, San Diego would be positioned to make some of its river allocation available to other states. Officials involved in early discussions describe the concept as a way to reallocate existing entitlements rather than creating new supply.
A small boat cuts across a Colorado River reservoir beneath exposed canyon walls, highlighting lower water levels amid drought and proposed water-sharing talks for Arizona.
The prospect of a sale comes as the Colorado River system and its major reservoirs sit at historically low elevations. Lake Powell and Lake Mead in particular are close to levels officials have identified as critical, raising the prospect of mandatory curtailments and shortages that would affect millions of users across the Basin. Proponents of the San Diego proposal argue that shifting use patterns now could provide relief to lower-basin states facing immediate pressures from prolonged drought and declining reservoir storage.
Aerial view of a Colorado River reservoir with exposed shoreline and reduced water, illustrating the urgency behind proposals to send more river water to Arizona.
Federal and state leaders have framed the emerging agreement as a test of regional cooperation. "This [Memorandum of Understanding] is a game changer for the entire Southwest United States, laying a strong foundation for the kind of collaboration and partnership that's going to carry us into the future," said Sen. Alex Padilla. A California congressman added that the arrangement demonstrates the ability of government entities to work together: "This is a demonstration that federal and local agencies, working together, can deliver results for California and the nation," said Rep. Ken Calvert.
San Diego officials say the proposed transaction could also help consumers in the county by stabilizing rates. Water rates in the San Diego area are among the highest nationally, officials note, and shifting some demand from river supplies to desalinated seawater could ease upward pressure on those costs for local ratepayers. How much of an impact the sale would have on rates, and how savings — if any — would be passed along to individual customers, has not been specified in the ongoing discussions.
Key elements of the proposed transfer remain open. Parties involved in early-stage negotiations have not finalized how much water would change hands, how long any transfers would last, or what price would be attached to the rights. Legal, regulatory and logistical issues will also need to be resolved before any agreement can move forward; for now, state and local officials describe the work as part of a memorandum of understanding and as a series of cooperative talks rather than a finished contract.
As the talks continue, the basic contours of the proposal are clear: by deploying desalinated seawater to meet a greater share of its needs, San Diego could free up a portion of its Colorado River allocation for sale to Arizona and Nevada. Supporters say the approach could be a template for cross-jurisdictional cooperation on the river, while the parties involved emphasize that the precise terms remain subject to further negotiation and approval. The water system’s declining levels and the prospect of shortages keep the discussions framed as a near-term response to an ongoing drought, with outcomes depending on the completion of detailed agreements and regulatory clearances.