Desalination – A Solution to Dwindling Water Supply?

Oct. 7, 2022

Desalination is often considered as an important option for augmenting Arizona’s water supply. WRRC Director Sharon Megdal has recently been consulted for news stories from NPR and ABC regarding desalination projects. In response to worsening shortage conditions and new funding for water projects, there have been renewed discussions about resuming operations at the inactive Yuma Desalting Plant and constructing two new plants along the Mexican Sea of Cortez. However, desalination comes with significant costs and environmental impacts, as Megdal pointed out. In 2020, the Binational Study of Water Desalination Opportunities in the Sea of Cortez estimated that the costs of desalinated water could reach $2,200 per acre-foot, compared to the $270 per acre-foot cost of Colorado River water. Megdal observed that for every gallon desalinated, “you’ll get a half gallon of good quality water, and then a half gallon of brine to dispose,” which could impact nearby ecosystems. During the construction of the Yuma plant, brine runoff created the Cienega de Santa Clara, a 15,000-acre-foot wetland in Mexico that is now home to endangered marine life and migratory birds. However, the plant has remained idle for 30 years. Resuming operations could disrupt that wetland ecosystem with an influx of heavily salted water. Megdal suggests that desalination should still be a part of the “portfolio” for water augmentation, but to create a more resilient water future, diversification of water resources and desalination tradeoffs should be considered as well.

Image: Yuma Desalting Plant, Bureau of Reclamation