Desalination: Should California use the ocean to quench its thirst?

A beach in Carlsbad, San Diego County, which has the nation's largest desalination plant. (Photo: Sherry V Smith, via Shutterstock)

As the state’s water supplies continue to dwindle during this drought, it’s always worth weighing the pros and cons of desalinization to meet the state’s water needs

Groundwater keeps shrinking, reservoirs keep drying. Is it time for California to use desalinization to increase its depleted water supplies?

Here we are again: California is enduring another punishing drought, this one only a few years after the last one ended, which was the most severe drought in the state’s nearly 500 years of recorded history. Low winter snowpack combined with scorching summer temperatures and the driest winter months in 100 years have severely impacted the state’s water supply. Lake Oroville, an important reservoir in Butte County, had sunk to 49% of capacity by July 1. Lake Shasta was at 39% capacity. Those are only two of many depleted reservoirs in the state’s water storage system. Every one of California’s 58 counties is under a drought emergency proclamation. As analysts know, drought drives California policy. So what has changed since the last drought?

A lot but not enough.

In 2014, the state passed the sweeping Sustainable Groundwater Management Act. Previously, California had no statewide policy either regulating or monitoring groundwater usage. Groundwater provides an estimated 30% of California’s water supply, yet no permits were required to drop a new well on private land, and there were no requirements for reporting how much water was withdrawn. Farmers rely on groundwater to grow crops during drought years when surface water is scarce, and without recharge, water tables keep sinking, causing subsidence, reducing supplies to utilize during the next drought, and drying shallower aquifers that support residences. By limiting how new wells get drilled on private land, the law aims to protect California’s groundwater from rampant over-pumping and lack of recharge and make sure it’s available during drought and non-drought years.

In 2018, Assembly Bill 1668 and Senate Bill 606 required local water suppliers and state agencies to establish long-term efficiency standards and water shortage contingency plans. In 2017, Californians used 90 gallons of water, on average, per day. Aimed at increasing water conservation by reducing and governing local use, this legislation set a standard limit of 55 daily gallons per person, with the amount set to reduce incrementally after January 1, 2025.

By 2027, fines will be imposed on local water suppliers who fail to meet standards during both drought and non-drought years.

Parts of greater Los Angeles are developing projects to collect rainwater and runoff from neighborhoods and parks and turn it into drinking water. Treating “wastewater” as usable water too precious to waste is wise long-term strategy, especially across the grand scale of large metro areas, and in conjunction with water conservation measures, water recycling, and lawn removal. That’s another excellent development: Los Angeles homeowners can receive financial incentives to convert their thirsty lawns into water-efficient, drought-tolerate landscapes.

Multiplied across thousands of lawns, such measures can save a lot of water for people, rather than grass, to drink.

The thing is, drought may drive policy, but droughts end, and people return to old habits in the gray areas and neglected spaces that policy has yet to change.

Even as some urbanites remove their lawns, many others keep watering theirs. Farmers still raise dairy cows in parched parts of the San Joaquin Valley where there’s scarce water or natural grass. And some of the benchmarks for achieving the Sustainable Groundwater Management Act’s groundwater sustainability goals are set two decades ahead of the law’s 2014 enactment, so its actual implementation leaves room for further over-extraction. During the current drought, private landowners keep drilling new wells and pushing others deeper while it’s still legal, chasing the disappearing water in what some describe as a frenzy. What’s changed since the last drought is the idea that California can go on like this forever.

The old way of doing things must be seen as over. As Gov. Jerry Brown said in 2015: “We’re in a new era. The idea of your nice little green grass getting lots of water every day — that’s going to be a thing of the past.”

In 2022, what’s already changed is the landscape: shifts in rain and snow patterns, and the timing of sensitive temperature changes, threaten the very system the state relies on. The way California’s water supply has worked in the past is no longer working, and it may soon stop working at all.

How California gets water
California gets part of its water from the massive Colorado River system, which also supplies Colorado, Utah, Wyoming, Nevada, Arizona, New Mexico, and Mexico. That system is failing. This June, the U.S. Department of Interior proposed cutting 2 to 4 million acre-feet from those customers, which is a historic, arguably unbearable, reduction. High level goals have shifted from delivering water to keeping the entire Colorado System from crashing.

The other part of California’s water collection and storage system works by capturing river and other surface water in reservoirs and transporting it to communities and farms. The wetter north has always watered the drier south, but it’s the Sierra Nevada snowpack, running through the state’s middle, that is the system’s keystone. In the simplest terms, a lot of California experiences a wet winter and dry summer. Most of the states’ snow and rain arrives between November and April. As spring starts to warm, the rains cease and the mountain snow melts, swelling creeks and rivers with freshwater, and recharging wetlands and aquifers. Dams now capture that runoff in reservoirs, which supplies the state through a network of canals. Climate change has changed this system dramatically.

Less rain fell in 2021 than in previous years. In fact, that was the second driest California winter on record. Snowpack was also lighter. Less snow means less water to fill reservoirs. The temperature also impacted supply.

Warmer temperatures in April and May melted snow at a faster rate in vital Sierra Nevada watersheds, including the Sacramento, American, and Feather rivers, and runoff evaporated more quickly.

Now here we are.

If the climate has changed enough that the terrestrial system California relies on no longer provides enough water, then logic dictates that the state must look beyond its borders, be it at other imported water, or to desalinizing the ocean that it abuts.

Fixing the state’s long-term water shortages has to involve reducing water use, creating efficiencies, and recycling. But it cannot depend entirely on those measures. Here’s why: The drought started in 2020, an emergency was declared in July 2021, and Californians have only reduced their water usage by 2%. The goal is 15%. In fact, this April, water use has actually increased by upwards of 26% in certain parts of southern California! A recent Pacific Institute study concluded that a combination of improved efficiencies and current technologies could reduce California’s urban water use by 48%, so why hasn’t that happened? Change happens so slowly, and it seems we’ve run out of time. Solutions that address the supply must explore ways to expand it, and desalinization seems like one obvious drought-proof solution. A severe drought is certainly a constructive time to weigh the pros and cons of desalinization once again.

The state of desalinization in California
The idea is an old one: California is perched beside a huge body of water, so why not take the salt out of the ocean and drink it? Framed that way, desalinization seems like a no-brainer: If the land won’t produce enough freshwater, then the ocean can make up the difference. Of course, it’s not that simple.

To be clear, California already has 11 operating desalinization plants of varying sizes and around 10 more pending approval.

The Claude Bud Lewis Carlsbad Desalination Plant in Carlsbad is the largest desal plant in the country. It went online in 2015 and cost approximately $1 billion dollars. In Santa Barbara, the smaller Charles E. Meyer Desalination Plant renders three million gallons of drinking water each day, sating 30 % of the city’s demand. There is a contentious proposal for a large plant on the Monterey Peninsula, but the Sand City Coastal Desalination Plant has been processing brackish water in Monterey County since 2010. The Southern California Edison facility produces about 200,000 gallons a day on Catalina Island. But the physical process of desalinating sea water is not only complicated, it’s complicated ecologically and politically, and that makes it contentious.

This May, the California Coastal Commission unanimously rejected the proposed $1.4 billion dollar Huntington Beach Desalination Plant for environmental reasons. Set on a low-lying coastal site, the Commission was concerned that the facility’s location exposed it to rising sea levels, and that its process for converting 50 million gallons of drinking water per day would harm marine life in 100 billion gallons of seawater each year. The plant’s aim was to reduce Orange Country’s dependence on imported water. Gov. Newsom supported the plant, calling desal “more tools in the tool kit,” but critics argued that the water the plant would produce would be too expensive for low-income consumers and never produce enough water to significantly move the county toward greater water independence.

So who do you believe?

A severe drought is a constructive time to weigh the pros and cons of desalinization once again.

The pros and cons

1) Costs
To many critics, desalination is prohibitively expensive. There’s the cost of building the facility, then there are the ongoing operational costs. The Pacific Institute’s research shows that seawater desalination costs nearly four times more than water importation, and five times as much as capturing and processing rainwater. Certain costs have come down, but measured against other available options, water conservation and capture still seem much more practical that expensive desal.

2) Water volume
For all of desal’s promise, it doesn’t produce that much clean water. The nation’s largest plant only provides 10% of San Diego County’s water. Due to the nature of the process, only around half of the saltwater that a facility draws in can be made potable—half. And because the potable water that facilities do produce is more expensive than other available water, getting cheaper water elsewhere still resembles the preferable option. That’s the free market.

“If you look at existing and planned ocean desal in the state,” Stanford law professor Leon Szeptycki said in 2016, “it’s a small fraction of the state’s overall water demand. It adds up to just over 600,000 acre-feet (740 million cubic meters) a year, compared to overall freshwater withdrawals of something like 34 million acre-feet (41,938 million cubic meters) a year.” That isn’t enough to truly offset California’s ongoing drought troubles.

3) Ecological damage
When desal plants draw in seawater, they kill millions of marine organisms in the course of a year. Then, once the process physically separates the salt from the water, the dense byproduct must be disposed of, and historically, that concentrated brine has been discharged into the ocean. Because the byproduct is heavier than seawater, it doesn’t simply mix back in. It sinks, damaging the marine ecosystem it comes in contact with. One solution is to blend the byproduct back into the seawater using sprayers or special pipes to disperse the water over greater areas more effectively. That is also expensive.

4) Carbon footprint
Pumping enormous volumes of water from the ocean through pipes requires large amounts of energy. And pushing that water through the membranes to remove the salt also requires large amounts of energy. Some estimates state that seawater desalination uses up to three times more electricity than various water recycling technologies. Critics argue that importing water from the Colorado River Aqueduct, recycling local wastewater, and instituting local efficiencies are far more energy-efficient options for a thirsty state in the throws of climate change. As states like California work hard to reduce greenhouse gas emissions and their reliance on fossil fuels, using this much power to produce clean water seems to take the state backwards, not forward.

Newsom is already preparing to counter potential summer blackouts by purchasing power from gas-fired plants, complicating the state’s clean energy goals. Desal plants emit large amounts of greenhouse gases. Then there’s the fluctuating cost of energy in California. Energy prices often increase during droughts, due to reduced hydrological power. The turbines can’t spin if there isn’t enough water, and lack of water is what we’re trying to solve in the first place.

Where do you go from there?
“We always backslide after a drought,” Jeffrey Mount, a senior fellow at the Public Policy Institute of California, told The Los Angeles Times in June, “but we backslide to a level which isn’t as high as it was before the drought, and that’s how we make progress in conservation.”

But how much more time does California have to make such slow, incremental progress?

The current drought is the state’s second extreme drought in a single decade, and the State of California calls that historic situation “a symptom of a warming climate.” Drought drives California policy, but with climate change driving drought, it’s time to speed up and diversify the way the state both conserves water and sources it.

Ultimately, when you view the desal process’ large carbon footprint through the wide-angle lens of climate change, the cost benefit analysis makes it look like an unattractive means to supplying the state. Maybe scientists can devise ways to offset some of the current drawbacks, such as drawing water from deeper waters rather than along the shore, and maybe certain operational costs will come down, but the idea of finding renewable sources of energy to power smaller plants seems difficult, considering that bigger plants have greater economies of scale.

Desal won’t save California from its thirst, because too many factors conspire to keep it from contributing more than a relatively small volume to the state’s total water needs, but as part of a diverse portfolio of conservation approaches, recycling, waste and stormwater capture, and other efficiencies, desal may still help—especially in coastal communities that don’t receive water from the State Water Project. Because frankly, it remains unclear how long northern California and the Colorado River can supply the rest of the state. It certainly seems unwise to bank on them for much longer. Maybe it’s finally time to dip more of the proverbial straw into the ocean that has helped define the Golden State’s image, economy, and recreation. Or maybe it’s time to stop looking for more resources to exploit at great cost and find ways to maximize the resources we have and minimize our footprint.

Avoiding that is what got us into this mess in the first place.

Editor’s Note: Corrects portion of San Diego water to 10%, 28th graf.

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