Arizona officials are evaluating two international desalination proposals that could help the state offset looming cuts to its Colorado River allotment. Both projects would pull seawater from the Sea of Cortez, desalinate it, and keep the fresh water in Mexico in exchange for Arizona receiving a larger share of the river.
Proposals from EPCOR and Acciona
Canadian firm EPCOR Water Innovation Partners and Spanish company Acciona have each submitted a plan to the Arizona Water Infrastructure Financing Authority (WIFA). EPCOR’s design calls for a plant twice the size of the world’s largest existing desalination facility, capable of drawing 1.2 billion gallons of seawater daily and producing about 446 million gallons of fresh water. The plant could be sited off the coast of San Felipe or near a geothermal power plant close to the U.S.–Mexico border in Baja California.
Acciona’s proposal is smaller, targeting up to 312 million gallons per day. The company suggests locating the plant somewhere along the north or eastern coast of the Sea of Cortez in the Mexican state of Sonora. Both firms intend to power the plants primarily with renewable sources—geothermal energy from the Cerro Prieto plant near Mexicali and supplemental solar generation.
How the “paper water” exchange works
Under the arrangement, the desalinated water would remain in Mexico, while Arizona would earn the right to draw additional water from the Colorado River by taking a portion of Mexico’s allocated share. This concept mirrors a water‑swap effort currently pursued by the San Diego County Water Authority, which is negotiating to purchase desalinated water from its Carlsbad plant.
Arizona’s legislature allocated $1 billion to WIFA in 2022 to jump‑start projects that could augment the state’s water supply. Ben Alteneder, assistant director for external affairs at WIFA, said the proposals are still conceptual and no construction has begun. He noted that Arizona will be among the first states to face deep cuts under a federal plan that requires a 3 million‑acre‑foot reduction in Colorado River use by 2036.
Environmental and political considerations
Both proposals avoid a contentious issue that derailed a prior $5.5 billion desalination plan with Israeli firm IDE Technologies, which would have shipped treated water 200 miles from Sonora to Phoenix. That plan was rejected after Sonora Governor Alfonso Durazo warned that the state would be left with the waste brine.
Environmentalists also raise concerns about the Sea of Cortez, a UNESCO‑designated marine area home to hundreds of fish and plant species. Mexico’s President Claudia Sheinbaum, a climate scientist, emphasized the need for studies on how to handle the salty brine by‑product.
International agreement requirements
Any water‑swap would require a new “Minute” agreement between the United States and Mexico, building on Minute 323 signed in 2017, which allows Mexico to store river water in Lake Mead. The International Boundary and Water Commission (IBWC) and its Mexican counterpart CILA would negotiate the terms. IBWC spokesperson Frank Fisher said it is too early to predict when talks might begin.
Both EPCOR and Acciona declined to comment further on the projects.
Original reporting: Voice of San Diego — read the source article.
