The dream of hyper-abundant water can come true, soon.
W e are told that water scarcity in the arid American West is inevitable and that the great water projects of the past century were the product of misguided hubris. Environmentalists call for Westerners to shrink their agricultural sector and ration their urban water use and, increasingly, demolish the dams and reservoirs that enabled a civilization they have now declared is unsustainable.
They are wrong. In the far West, California’s chronic water scarcity — as well as many of the threats to aquatic ecosystems in that state — are caused by mismanagement. There is plenty of water. Year after year, clouds packed with moisture blow in from the Pacific and dump rain and snow on California’s coastal mountains, then cross the Central Valley and dump even more onto the peaks of the Sierra Nevada Range. In an average year, nearly 200 million acre-feet of water pours onto California’s in-state watersheds. But thanks to the state’s failure to invest in new water-supply infrastructure, and thanks to burdensome environmentalist regulations that are dogmatic and counterproductive, much of this abundance is squandered.
Merely contradicting the narrative of water scarcity does not do justice to the opportunity inherent in California’s geography. With smart investments and reformed policies, Californians can keep all their irrigated farmland productive and expand their cities without resorting to water rationing. But if they tap the waters of the Pacific Ocean by building desalination plants — both onshore and offshore — along portions of their more than 800-mile-long coastline, Californians can move from achieving water abundance to achieving water hyper-abundance.
Imagine “water farms” off the Southern California coast desalinating 4 million acre-feet of water every year. With this much additional fresh water, combined with wastewater recycling and runoff capture, Southern California’s 25 million people wouldn’t need to import water from aqueducts. Some of these aqueducts would stay operational as backups, but water security in the arid megacities of Los Angeles and San Diego would no longer depend on how much rain falls in any given year in California’s far north.
These same water farms could operate off California’s central coast, delivering an additional 1 million acre-feet per year to the 7.5 million people living in the San Francisco Bay Area. And in similar fashion, combined with runoff capture and wastewater recycling, this region too would no longer need to import water via aqueducts.
With abundant surplus water, greater Los Angeles could be turned into a garden city. The Los Angeles River and every stream feeding into it could spring to life thanks to year-round flows, with much of the water percolating into local aquifers for reuse. Storage reservoirs surrounding Los Angeles, along with those located on the mountain perimeters of all of California’s coastal cities, could be kept full, in a permanently ideal state for groundwater recharge, fire fighting, and recreation. Far less restricted outdoor water use would nurture the urban forest, mitigate the urban heat island, and lower the region’s “vapor pressure deficit,” those dry air conditions that increase wildfire risk. And, of course, household water use would no longer need to be rationed.
The dream of urban water abundance extends well beyond the cities where it may be achieved. The Hetch Hetchy Aqueduct feeding San Francisco could be deactivated, and the O’Shaughnessy Dam could be demolished. John Muir’s nightmare would come to an end, as the currently inundated Hetch Hetchy Valley, twin to the majestic Yosemite Valley, could be restored to its primeval glory. At the same time, the Los Angeles Aqueduct could also be deactivated. Not only would this allow farming and habitat to be restored in the Owens Valley, from which the Los Angeles Aqueduct diverts water. It would also allow the headwaters of the Owens River to flow in sufficient volume into Mono Lake to refill that lake to its natural level, ensuring that its unique ecosystem will be revitalized and will remain a vital link in the Pacific Flyway for migratory waterfowl.
Urban self-sufficiency in water would also benefit a manmade ecosystem, the sprawling Salton Sea, a 350-square-mile artificial lake that was created by accident just over a century ago when, for nearly two years, the Colorado River was accidentally diverted into what had been a dry basin below sea level. Southern California cities currently receive around 1 million acre-feet of water per year from the Colorado Aqueduct. This water could be returned to farmers in the Imperial Valley, who for years drained their irrigation runoff into the Salton Sea to prevent it from drying up. Many other factors challenge the survival of the Salton Sea as an ecosystem and tourist destination, and any restored volume of irrigation runoff would have to be better treated than in previous decades. But without more water, the Salton Sea is doomed.
Reducing urban reliance on Colorado River water will not only allow more water to be reserved for Imperial Valley farmers and to refill the Salton Sea, but also some of that million acre-feet per year can be left in the Colorado River to benefit downstream ecosystems or to help other Colorado Basin states to meet their own water requirements.
Unlike other states in the American Southwest, California is uniquely able to dramatically increase its water supply through a variety of projects for which there ought to be a consensus as powerful as the one that drove the first great era of water infrastructure construction. The State Water Project in the 1950s and 1960s created the magnificent system of reservoirs and aqueducts that have sustained the state’s farms and cities for the past 70 years. The scope of what could be accomplished today is transformative. Even without desalination, Californians have the opportunity to add 10 million acre-feet per year to their water supply. (California’s farmers now use about 30 million acre-feet every year, and California’s cities use about 8 million acre-feet every year.) The addition of 10 million acre-feet can be done through the projects described in more detail in a previous article, from forest thinning to increase runoff to restructured delta-pumping rules.
Contrary to conventional environmentalist wisdom, options to restore wetlands and aquatic habitat in the Sacramento-San Joaquin Delta are enhanced, not undermined, by this much additional water. For example, increased dredging allows more water to be retained in reservoirs because flood currents can move at higher volumes through dredged channels. And it also creates deeper channels where the water is cooler, which helps migrating salmon. More surface storage means there is a bigger stock of water to allocate between releases for farm irrigation and ecosystem maintenance. Better, safer ways to remove water from the delta during winter storms, along with better runoff capture from the Sierra tributaries, help with groundwater recharge. And all this extra water permits farmers the option to resume flood irrigation, which helps desalinate cropland and recharge aquifers.
If 10 million acre-feet per year of additional water through conventional projects were supplemented by another 5 million acre-feet from desalination at a massive scale, California would achieve a level of water abundance that would make projects environmentalists dream of move from fantasy to reality. Restoring Hetch Hetchy Valley, refilling Mono Lake, and saving the Salton Sea would be only the beginning. Restoring wetlands, saving the delta, and greening our cities would all become politically achievable, because they would not have to come at the cost of reduced farming or urban rationing. It’s a failure of imagination to close our eyes to the environmental upside of hyper-abundant water through an ambitious but perfectly feasible 21st-century version of the State Water Project.
The viability of massive-scale desalination has already been proven. Primarily via conventional land-based reverse osmosis filtration, worldwide desalination capacity now exceeds 30 million acre-feet per year, which is about 1 percent of total worldwide freshwater diversions, and an impressive 7 percent of worldwide municipal water consumption. Desalination at scale is already cost-competitive, with many water-supply options that we take for granted. Worldwide capacity is projected to double over the next seven years.
The energy cost of desalination remains a major objection to its adoption, but that objection relies on obsolete assumptions. The energy required using current reverse osmosis technology — where salt water is pumped through a filtration membrane, with the fresh water collected on the downstream side of the membrane, and the saltier brine continuously removed from the upstream side of the membrane — has dropped by a factor of ten in the past 50 years. Advances in pump efficiency, membrane design, and energy-recovery designs have all led to tremendous energy savings.
To put this into perspective, using existing technology (about 3,500 kilowatt-hours per acre-foot) to extract 5 million acre-feet of fresh water from the ocean would consume roughly 17,500 gigawatt-hours. This is equivalent to the output of the Diablo Canyon nuclear power plant, or 6.3 percent of the 281,140 gigawatt-hours consumed in California in 2023. While that may still seem significant, it should be viewed in the context of California’s plan to electrify most of its economy by 2045. California’s state legislature intends to double the state’s electrical consumption, to well over 500,000 gigawatt-hours per year. Compared to that aspiration, allocating up to 17,500 of those gigawatt-hours for desalination is small potatoes. Energy consumption is not a reason to deny Californians millions of acre-feet of desalinated fresh water.
Another argument against desalination is that the brine, that saltier water that is left over when fresh water is extracted from seawater, constitutes a threat to marine ecosystems. Desalination brine is typically twice as salty as seawater, i.e., for every acre-foot of freshwater extracted from seawater, there is an acre-foot of water left over that is twice as salty. But the impact of brine on ocean ecosystems can be overstated. While prolonged discharge of brine in one location has the potential to degrade ocean habitat, conventional desalination plants are designed to release the brine under pressure from multiple points underwater to disperse the brine and dilute its impact.
Moreover, we also have the benefit of the California Current. One of the biggest ocean currents in the world, the California Current moves nearly 300 billion acre-feet past the coastline every year. As a result, even if 5 million acre-feet of brine were discharged into the ocean off the California coast every year, the ratio of ocean to brine would still be only 60,000 to 1. The dispersion capacity of the California Current ensures that any responsible design to release brine into the waters off California will be quickly diluted to negligible levels at any conceivable scale.
While land-based desalination plants using reverse osmosis technology have the potential to deliver millions of acre-feet of freshwater from the ocean into the aquifers and reservoirs of California’s coastal cities, there are new technologies to desalinate that may disrupt what is already a thriving worldwide industry. The concept of deep-water desalination has been around for decades, but only in recent years has the enabling technology been available, thanks to innovations pioneered for the offshore oil and gas industry.
A California-based company, OceanWell, aims to take advantage of these to use deep-water desalination to dramatically reduce the energy cost, the environmental impact, and the financial cost of large-scale desalination.
OceanWell’s design relies on performing desalination at a depth of around 1,300 feet, where they intend to tether pods to the sea floor. Production-sized pods will measure roughly 40 feet long and 25 feet in diameter. Ocean water will enter the pod, where fresh water will pass through a filtration membrane, while a circulating pump on the saltwater side of the membrane creates a cross flow that expels the brine back into the ocean. The fresh water that collects inside the pod on the other side of the membrane will feed a subsea pump and pipeline to shore that is shared by several pods.
While this description excludes countless relevant details, it is important to highlight the reasons this design has such disruptive potential. It lies in the fact that as the subsea pump pushes the fresh water up through the underwater pipe to an onshore collection facility, it creates lower pressure on the fresh water side of each pod’s interior. On the seawater side of the membrane, undersea pressure at 1,300 feet is about 600 PSI, but on the freshwater side of the membrane, the pressure inside the pod is lowered by the subsea pump to around 250 PSI. This is enough to pull fresh water through the membrane at a rate the company predicts will be one million gallons per day per pod.
The expected energy savings are based on a simple but fundamental difference between deep-water desalination and onshore desalination: When the membrane performs the desalination process underwater, only the fresh water has to be pumped, whereas in an onshore desalination plant, ocean water, including the eventual brine that is 50 percent of the volume, has to be pumped up from the ocean intakes and pushed through the filtration membranes. OceanWell estimates that their energy cost will be approximately 2,250 kilowatt-hours per acre-foot of fresh water, roughly a third less than the energy required by today’s commercial onshore desalination plants.
The environmental impact of deepwater desalination ought to be less, too. The brine is less concentrated and is released from dozens of distributed pods that are deep underwater. The potential for underwater biota such as plankton or fish larvae to get trapped in the membranes is reduced not only from prescreening and cross-flow circulation pumps around the membranes, but also because the membranes perform under lower intake pressure than conventional desalination plants, and also, crucially, because the amount of marine life at a depth of 1,300 feet is far less than at or near the surface where typical land-based desalination intakes are located.
Moreover, OceanWell’s approach, using mass-produced pods that form underwater “water farms,” could dramatically lower the price of desalinated water. While the company’s current production cost estimates are proprietary and in any case still dependent on testing results and future variables such as materials costs that are uncertain, imagine if the installed cost for each production pod was $5 million, and for each pod in a large water farm, there was an equivalent additional cost for subsea pumps, pipelines, onshore facilities, and so on. This means that a 50-pod water farm, producing 50 million gallons per day of fresh water, would cost $500 million. Compared with traditional desalination plants, this is barely one-third as much — the proposed Huntington Beach desalination plant was projected to cost $1.4 billion dollars to deliver the same quantity of fresh water. But until we know how much these pods and other systems are really going to cost, this is speculative.
Other desalination technologies are being developed that also show promise. Scientists at MIT have prototyped a desalination system that uses thermal energy from sunlight to distill fresh water from ocean water or brackish water. Another MIT team has developed a traditional reverse osmosis system that runs on photovoltaic electricity, using a pump that adjusts its speed and operating times to the amount of solar power available. By introducing this flexibility, the need for batteries is eliminated, greatly reducing system cost. These potentially low-cost, off-grid systems could find niches on islands, or remote inland regions where only brackish water is available.
It is to be hoped that California’s regulatory agencies don’t treat OceanWell’s proposals with the same obstructionist zealotry with which they delayed, then killed, the desalination plant proposed for Huntington Beach. With any luck, OceanWell’s systems may prove to be leapfrog technologies that silence even the most confirmed skeptics of desalination. But while California dithers and delays any project that might yield even an incrementally increased supply of water — or any other essential — much less facilitate the achievement of abundance or hyper-abundance, Texas is stepping up.
True to the old cliché that everything comes big in Texas, the state’s Water Development Board has recommended construction of dozens of seawater and brackish water desalination plants over the next decade. The largest, located near the Port of Corpus Christi, is proposed to deliver 100 million gallons per day, with a follow-on possibility to expand capacity to 450 million gallons per day, which would amount to a staggering 500,000 acre-feet per year from one desalination complex.
If plans for desalination in Texas reflect the kind of ambition California could use, the projected capital costs exemplify a building environment that Californians currently can only dream of. The major proposed desalination plants in Texas come at a total project budget that amounts to $12,000 construction cost per acre-foot of annual capacity. This is reverse osmosis desalination, conventional technology, delivered at one-third the cost it would incur if built in California. Texas also has far less expensive electricity, which would make operating costs for desalination plants far lower as well.
Nevertheless, despite paralyzing bureaucracy and endless litigation in California, the state is still the center of desalination innovation in the United States if not the entire world. OceanWell’s emerging desalination technology is evidence of this, but that only scratches the surface. The technology innovators in California’s Silicon Valley who invented the integrated circuit, commercialized the internet, built massive data centers, and who are now are rolling out artificial intelligence, are going to engineer electricity abundance. Facing the necessity to add dozens of terawatt-hours to California’s electricity capacity, they will design and build the systems to produce that energy, and they will use their influence to ensure that the state legislature doesn’t get in their way. Abundance is becoming a bipartisan mantra, and when it comes to electricity, tech billionaires will make it happen.
Ultimately, and to state the obvious, the possibility of abundant water through investments in proven water supply infrastructure and commonsense reforms to water policy is a political choice. But the possibility of hyper-abundance, also a political choice, holds out the promise of a grand bargain that unites environmentalists with California’s businesses and households. With a hyper-abundance of water, realized through adding large-scale desalination to California’s upgraded mix of water-supply options, the state’s farms can thrive, the cities will not have to ration water, and the state’s ecosystems can be not just saved, but enhanced.
It is only a small stretch to imagine walking in cool groves of Sequoia redwoods along the wild Tuolumne River as it meanders again along the floor of the revivified Hetch Hetchy Valley, and know that water farms off the California coast were the missing link that made it all possible.