The largest U.S. desalination plant is located in Tampa Bay, Florida, and is co-located with a power plant. Image: Natural Resources Defense Council (NRDC)

Desalination is the process of removing salt from saltwater through reverse-osmosis, a process where saltwater is forced through tiny membranes that filter out salt and minerals, thereby creating freshwater.

Currently, 19 desalination plants (that plan to generate 85-145 billion gallons of water each year) are proposed along the coast of California. Nine of these proposals are located in Los Angeles, Orange, and San Diego counties.

The Problems
Many of the proposed desalination plants involve co-location with the same aging coastal power plants that utilize the outdated once-through cooling technology.

Co-located facilities are designed to pump the used cooling water from power plants into the desalination plant. While at first blush this might seem like a positive reuse of intake cooling water, it may actually prolong the use of harmful once-through cooling technology by providing outdated coastal power plants an argument against making the federally required upgrades to newer cooling technologies.

Desalination plants also discharge a concentrated by-product, which raises additional environmental concerns. For instance, this brine effluent may create localized spots along the coast that are too salty for sea life to live or induce stress on organisms that already live in these areas.

Heal the Bay’s Position
Rushing into desalination without sufficiently considering its environmental impacts may worsen already significant environmental problems along California’s coast. For these reasons, Heal the Bay believes that alternative sources of fresh water, including water conservation and reuse, should be utilized before considering desalination, which is also energy-intensive and fairly expensive.