By John — Desalination News
Over a decade after it opened, the Carlsbad Desalination Plant remains the largest seawater desalination facility in the Western Hemisphere — and a case study in both the promise and the price of turning ocean water into drinking water. Built at a cost of roughly $1 billion under a public-private partnership between Poseidon Water and the San Diego County Water Authority, the plant has produced around 50 million gallons of fresh water a day since opening in December 2015, supplying about 10 percent of San Diego County’s total demand.
The appeal is straightforward: unlike imported river water, Carlsbad’s supply doesn’t depend on rainfall, snowpack or allocations from the Colorado River, giving the region a source of drinking water that keeps flowing through drought. That resilience comes at a price, though. Water from the plant has been estimated to cost well over twice as much as water imported from other sources, and the facility draws roughly 35 megawatts of electricity to run its reverse osmosis system — a significant ongoing bill layered on top of the initial billion-dollar build, one that has occasionally spilled into disputes over who pays when output falls short.
Environmental concerns have proven just as persistent as the cost debate. Drawing in large volumes of seawater risks trapping and killing fish and other marine life at the intake screens, while the concentrated brine left over from the process is discharged back into the ocean; Carlsbad’s own intake and discharge system has since been redesigned to reduce that impact. The same marine-life concerns were central to California regulators’ 2022 rejection of a similarly sized, $1.4 billion plant proposed for Huntington Beach.
Carlsbad’s backers argue the plant has already proven its worth by giving San Diego a drought-proof supply that isn’t at the mercy of statewide water politics — an argument that has gained ground as other California communities revisit desalination amid deepening drought. Critics counter that the same billions could have gone further on water recycling and conservation. A decade in, the debate that greeted the plant’s approval hasn’t gone away — it has simply moved from whether Carlsbad should be built to whether it should be the model for the next one.
(Source: The Economic Times)