By Edward Ring
In debates over water policy in California, a common argument is that if only we managed the systems we’ve already got, there would be plenty of water for everyone. Agricultural and urban use would not have to be rationed, taxpayers and ratepayers would not have to be unnecessarily burdened, and we wouldn’t have to wait years (ok, decades) for new water projects to navigate the gauntlet of bureaucracy and litigation.
This is a compelling argument, and perhaps we should just let the delta pumps run a bit more while engaging in ultra cost-effective projects, such as dredging the delta and constructing innovative new ways to safely withdraw millions of acre feet from the delta during winter storms. But if Californians want to achieve permanent water abundance, how we manage the Sacramento-San Joaquin Delta should not be our only option, but instead be the centerpiece in a much broader vision.
We can keep the San Joaquin Valley verdant with farms and orchards, and we can rehydrate our coastal megacities. We can daylight our urban creeks and rewild downtown sections of the Los Angeles River. We can create so much water abundance that completing the restoration of Mono Lake’s historical shoreline and demolishing the O’Shaughnessy Dam to restore the Hetch Hetchy Valley will have an inconsequential impact on water availability in Los Angeles and San Francisco. We can do it all.
To make this grand bargain, figuring out how to take the “big gulp” and store an additional 3-5 million acre feet per year from the Sacramento-San Joaquin watershed is the biggest single opportunity. Optimizing our capacity to harvest urban runoff and recycling 100 percent of urban wastewater is likely to contribute another 2-3 million acre feet per year. Which brings us to the potential of large-scale desalination plants to offer another major source of fresh water. It is reasonable to assume desalination plants on the California coast could deliver 1 million acre feet per year of fresh water to our coastal cities.
An example of this is found in Israel, where in 2025 a network of desalination plants along the Mediterranean Sea delivered 650,000 acre feet of fresh water. By 2027, with the addition of new plants currently nearing completion, the annual total will rise to 730,000 acre feet. And the environmental impact is minimal. The salt water comes in via underwater pipes that are large diameter to reduce the intake velocity, with screens and nets to filter out debris and organisms. The brine that is discharged from these desalination plants has roughly twice the concentration of salt as the ocean, and it is released under pressure in areas with currents so it is rapidly dissipated. Chemicals used during the desalination process are removed from this effluent before it is released back into the Mediterranean Sea. The Environmental Assessments performed by Israel’s Ministry of Environmental Protection monitors these desalination plants and has concluded their environmental impact is negligible.
In California, with far more available coastline and a far more robust offshore current, the environmental impact would be even less.
As for the energy required for desalination, it is important to keep two things in mind. First, we should assume that California is within 10-20 years of having abundant, affordable, surplus electricity. This could already be the case if we would quit shutting down a natural gas power plant every time another 100 MW solar/battery farm gets built. But whether it’s today, or a decade or so from now, electricity is going to be cheap and plentiful again. Server farms with inside-the-meter SMRs will be selling power to the grid. Improvements in the price and performance of batteries are going to turn electricity produced by intermittent sources into competitively priced baseload power. EVs are going to store and sell power to the grid when they’re not actually being driven. All we have to do in order to have cheap energy in all of its forms is to quit shutting down conventional sources faster than new sources are developed.
Second, however, desalination doesn’t require very much power. Even using today’s technology, it only takes 3,500 gigawatt-hours (GWh) for seawater desalination plants to produce one million acre feet of fresh water. Californians consumed nearly 300,000 GWh in 2024, with the state’s official goal to produce 500,000 GWh per year by 2045. We could easily exceed that total before that if we’d just retrofit our natural gas power plants and let them generate baseload power (90 percent uptime) instead of only turning them on to cover peak demand (25 percent uptime). Either way, allocating barely one percent of California’s electricity supply in exchange for one million acre feet of fresh water per year is not an unsustainable burden.
Finally, there is the cost of desalination plants. The current cost – in California, where capital projects cost twice as much, or more, than what they cost in other states and nations – is around $1.0 billion for 50,000 acre feet per year of capacity. The financing cost for this based on a 30 year, 4 percent construction bond would be $1,157 per acre foot. If with federal assistance that rate was lowered to 2 percent, the financing cost would drop to $893 per acre foot.
What about the cost for electricity?
At a consumption of 3,500 kilowatt-hours per acre foot, if desalination plants were to negotiate a wholesale price for electricity – which is consistent with rates the State Water Project pays to power their pumps – then even at $0.08/kWh that would only add $280 to the price per acre foot. Other operating costs for desalination do not add significantly to these totals. Desalinated water can be sold at rates that municipalities in Southern California are already paying, and it is conceivable that in time, as the technology continues to improve, the prices will come down further.
The unavoidable question is this: How do we pay for new water supply infrastructure? Even if costs for desalination are becoming competitive with many other solutions, we still have to find the billions of dollars it’s going to take to build these plants. We can begin to answer that question by acknowledging that conservation has a price, too. The cost to implement the state legislature’s next stage of urban water rationing is estimated at $7 billion to save 400,000 acre feet per year. That is roughly equal to the cost to construct seawater desalination plants able to produce 400,000 acre feet of fresh water per year. We can start right there.
And then there are the tens of billions the state is wasting on subsidized housing, when a deregulated private sector could build homes at affordable prices, generating tax revenue instead of consuming tax revenue. Perhaps additional billions would be set free if our politicians would build large congregate shelters that cost-effectively offer both safety and counseling, instead of subsidizing the homeless industrial complex.
To continue would be to stray from the main point: Desalinated seawater is a sustainable solution that can compete with other sources of urban freshwater at a price ratepayers can afford. Large scale seawater desalination is no longer a water supply option that should be dismissed in favor of other options, but rather should be part of a comprehensive state strategy to create permanent and drought proof water abundance.
