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Drought: How one Orange County water district drilled down to become self-sustaining

They call it “redwood tea.”

More than 100,000 years ago, a forest of redwood trees grew along Southern California’s then unspoiled coast. Today, on a wedge-shaped strip of land along the 405 freeway, next to a CarMax dealership, two massive wells pull water from 1,000 feet beneath the city of Costa Mesa — an aquifer from ground where those redwoods once grew.

The water that is brought to the surface is clear but with a light amber tinge, much like weakly brewed tea.

That water is 12,000 years old, untouched by pesticides or forever chemicals or other contaminants too often found now in aquifers closer to the surface. It’s safe to drink straight from the ground, but decaying matter from the buried, prehistoric redwood forest gives the water its trademark color. So Mesa Water District, the agency with the freeway-adjacent wells, has invested some $40 million into a system that pumps, purifies and stores that “redwood tea” until it’s ready to go out to 110,000 thirsty residents.

Thanks to that process, Mesa Water is celebrating 10 years as the only agency in Orange County (and one of only a small number in California) to get 100% of its supply from local groundwater. That change has slashed the district’s carbon footprint in half and is helping to insulate residents from more draconian water restrictions others in the west are facing — and from the fear that outside water sources might one day dry up entirely.

With the Southwest facing its worst drought in 1,200 years, Tim Godwin, who focuses on sustainable groundwater management for the Department of Water Resources, a state agency that helps manage water supplies throughout California, said most water districts in the state are looking to become as self-sustaining as possible.

Most water districts in California import some or all of their water from Northern California, the Colorado River, or some combination of the two. But imported water costs about twice as much, on average, as local groundwater. It also takes a lot more energy to bring water from those sources to people’s homes, meaning more carbon goes into an already warming atmosphere.

And as is becoming clear during the current drought — which has left the Colorado River and its crucial reservoirs at historic lows — future drought conditions are likely to mean more restrictions and interruptions on imported water.

Not every water district is like Mesa, fortunate enough to be sitting on two layers of underground aquifers. Still, experts say some water districts in California and throughout the country could pivot to greater reliance on local groundwater supplies. And even if they aren’t as geologically blessed, experts say there are lessons to be learned from the bold — and potentially costly — moves Mesa Water took to become water independent.

“There are a lot of local options,” said Paul Shoenberger, general manager of Mesa Water District. “But they do cost money. So you have to have leaders with the vision and political fortitude to get it done.”

Looking local

Half a century ago, Mesa Water, like many others in Southern California, relied on imported water. But in the late 1970s, as California experienced what was then its driest period on record, Shoenberger said the Mesa Water board set a goal to become more self reliant. And that’s been their goal ever since.

Mesa — which serves residents in Costa Mesa, a sliver of Newport Beach and unincorporated Orange County around John Wayne Airport — is one of 19 cities and districts in north and central Orange County that’s lucky enough to sit on top of a massive groundwater basin fed by the Santa Ana River.

More than 500 groundwater basins have been identified throughout California, Godwin noted. But while places such as the San Joaquin Valley have used so much of their underground supply that the ground surface is literally sinking, Godwin said Orange County Water District has served as a model for effective groundwater management.

Orange County Water District controls how much water Mesa and other districts can pump annually, regulating the flow through a complex system of diverted river water, recycled water, captured storm water and imported water in a way that keeps the underground aquifer replenished. Thanks to that careful management, three in four Orange County residents, including Mesa customers, now get around 77% of their supplies from that clear-water aquifer some 600 feet underground without any reports of the ground sinking or other negative side effects.

Still, Shoenberger said his district’s goal — water independence — prompted the board to look for ways to replace the 23% of its supply that, for a time, was imported. So, in the early 2000s, the agency decided to look below — about 400 feet under the upper aquifer — to an “amber zone” of water that hydrogeologic studies had identified as far back as the 1950s.

The phenomenon of groundwater basins being layered on top of each other isn’t uncommon in California, Godwin said. But, sometimes, the water in those deeper aquifers is too salty or otherwise is impractical to be tapped.

That wasn’t the case for Mesa’s amber zone.

It took about six months for crews to drill two wells 1,000 feet under the district’s Mesa Water Reliability Facility along the 405 freeway. The water those wells reached is safe to drink and incredibly soft, which is great for plumbing and avoiding water spots. But there is a pesky amber color to deal with. So crews built out a small plant where the water passes through sand and charcoal filters before it’s pushed through nano-filtration membranes. The water molecules are small enough to get through the filter while the molecules from the organic matter — which imbues the water with its amber color — are not.

The process of pulling the water up through the 1,000-foot well, filtering out the redwood particulates, and sending the clean product into the facility’s 1 million gallon storage tank takes about an hour. Mesa doesn’t need to tap that secondary aquifer during the winter months, Shoenberger said. But they’ve been using the system for about eight or nine months each year for the past decade, with the ability now to supply up to half of their water from the amber aquifer if needed.

The entire project costs about $40 million. That’s a lot of money, particularly for a relatively small water district like Mesa. And while local groundwater costs about half as much as imported water, Shoenberger said his district will be just shy of breaking even on this project once capital expenses, debt financing and other costs are weighed against price savings. (Mesa can’t sell any excess water from the secondary aquifer, by the way, since they don’t own the water rights. Local ordinances confer only the rights to pump water used by the agency’s own customers.)

But while future price hikes on imported water could mean big local savings down the road, Shoenberger said the focus of this project was to create a clean, reliable supply for customers, not to lower costs. And. he added, they’ve managed to do just that while boosting customer rates only incrementally over the years, with Mesa viewed as one of the state’s most financially efficient districts on a per capita basis.

Looking forward

As experts raise flags about what the Colorado River might look like in 20 years, Shoenberger said hydrologists estimate that Mesa’s amber aquifer has enough water to meet local demands for at least 200 years — and possibly up to 500 years. That estimate, he added, factors in state housing goals that might drive up the local population by 30%.

Godwin said he squirms a bit whenever someone talks about projections hundreds of years out, because so much can change during that time. But if the deeper aquifer is carefully managed, as Orange County’s primary basin has been, Godwin believes it could serve as an example to other agencies that might use similar sources to come closer to water independence without causing secondary problems.

Mesa also isn’t taking its water supplies for granted, Shoenberger said. Even though its system has made the district much less susceptible to restrictions in times of drought over the past decade, residents still must follow state water-use rules, including current restrictions that limit outdoor watering. And Mesa staff has only increased its consumer messaging around being “water wise,” offering rebates and incentives for residents to reduce their water use.

As a result, Mesa Water users have done a better job than most of their neighbors at cutting back during droughts, reducing water use by nearly 29% from May 2020 to May 2022.

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