Rain brings little relief to California’s depleted groundwater
The powerful storms that clobbered California for weeks in December and January dropped trillions of gallons of water, flooding many communities and farms. But throughout the state, the rains have done little to nourish the underground supplies that are critical sources of California’s drinking water.
Thousands of people in the San Joaquin Valley have seen their wells go dry after years of prolonged drought and overpumping of aquifers. And a two-week deluge—or even a wet winter—will not bring them relief.
Even in January, as California’s rivers flooded thousands of acres, state officials received reports of more than 30 well outages, adding to more than 5,000 dry residential wells reported statewide in the past decade.
“Just one wet year is nowhere near large enough to refill the amount of groundwater storage that we’ve lost, say, over the last 10 years or more,” said Jeanine Jones, a drought manager with the state Department of Water Resources.
Groundwater is among California’s most precious natural resources, providing about 40% of the water consumed in most years. It is an inexpensive, local source in a state where many cities rely on imported water and rural towns have no other sources. And its importance is magnified in dry years, when reservoirs fed by rivers are depleted.
The San Joaquin Valley’s groundwater reserves have been relentlessly pumped by farmers for decades. Tens of millions of acre-feet have been pumped from the ground, causing the water table to steadily drop and thousands of wells to go dry.
A handful of communities, largely home to low-income Latino residents, have run out of water, forcing people to use bottled water for everything. The true scope of the problem, in fact, may be underestimated, since many dewatered wells are unreported.
“There’s so much political pressure to maintain the status quo, and to continue pumping, because it’s tied up with economic profits. And the end result is community members who can’t rely on their wells for safe water,” said Tien Tran, a policy advocate with the group Community Water Center, which advocates for water equity.
Almost a decade ago, California enacted a law that is supposed to protect groundwater reserves from overpumping. The Sustainable Groundwater Management Act requires local groundwater agencies to halt long-term depletion and achieve sustainability, defined by specific criteria. But the deadlines are almost 20 years away, and basins are still being overdrafted.
Compelled in part by state law, and often supported by millions in state funds, some farmers and other land managers have dug large recharge basins to capture stormwater and allow it to sink. Cities design similar projects, and in recent months alone, they’ve put tens of thousands of acre-feet of water into underground storage.
While not enough on their own to reverse overdraft, these programs could serve as models for scaling up recharge efforts statewide.
UC Davis professor of civil and environmental engineering Jay Lund said, while he endorses groundwater recharge projects, there is a better way to lessen the Central Valley’s water woes.
“We have to reduce demand,” he said.
The problem is that farmers are still pumping water out of the ground faster than it’s going back in.
Experts have predicted that the state groundwater law could eventually force as many as 750,000 acres of farmland out of production, permanently easing demands on the state’s water supply.
The groundwater plans that the state rejected last year were revised and resubmitted in July, and the state is expected to announce their next round of San Joaquin Valley assessments within two months.
Water equity activists who have studied the revised plans say they’re not impressed by the changes made.
“We still found that these plans are not taking adequate steps to protect drinking water users in the basins,” said Nataly Escobeda Garcia, policy coordinator for water programs with the NGO Leadership Counsel for Justice and Accountability. “We anticipate that numerous domestic wells and public water systems will still be at risk of dewatering.”
With or without human intervention, water sinks into the Earth. Natural, or passive, recharge is the process by which hundreds of millions of acre-feet of water have accumulated in California’s shallow basins and deep aquifers. Recent research from NASA found that as much as 4 million acre-feet yearly may seep beneath the Central Valley.
But this doesn’t necessarily make a big difference. While the water can generate quick spurts of rebound of the water table, these post-rain gains—at least in the San Joaquin Valley—tend to be erased, plus some, by subsequent dry spells and continued pumping.
The result is a one-step-up-two-steps-down trajectory of groundwater decline.
“Overall water levels have been dropping, and until it’s reversed, we’re going to keep getting dry wells,” Fogg said.
Active recharge programs generated about 6.5 million acre-feet in the San Joaquin Valley alone in 2017, according to a report by the Public Policy Institute of California.
“We have lots of active recharge already,” said Ellen Hanak, vice-president and director of the institute’s Water Policy Center. “The question is, with (the groundwater law), can we up our game?”
Paul Gosselin, the Department of Water Resources’ deputy director of sustainable groundwater management, said 42 recharge projects underway with $68 million in state support could add 117,000 acre-feet of water storage to the state’s aquifers—a big step toward meeting the governor’s half-million acre-foot goal. He said the department has $250 million available to support more recharge work.
Changing climate makes this work all the more urgent. The state’s system of capturing and storing water in reservoirs was designed in part around snowpack in the Sierra Nevada. But as the climate warms, mountain snowpack is becoming scarcer. It is melting faster and earlier, and more precipitation is falling as rain in the first place.
California’s existing reservoirs don’t have the capacity to store so much liquid water at once, but its aquifers do.
“Groundwater recharge will be a good way to compensate for that change,” Hanak said. But, she said, “there is a major time constraint—you’ve got to be able to get that water out there fast, because it’s coming down fast.”
In 2018, Los Angeles County voters passed Measure W, which created a new tax on the owners of impermeable surfaces that direct water into storm drains leading to the ocean. Each year since its introduction, the tax has generated about $280 million in funds for use in supporting stormwater projects.
Since October, the county has captured more than 143,000 acre feet of stormwater in reservoirs and groundwater basins, according to Lisette Guzman, a public information officer with Los Angeles County Public Works. That’s enough water, she said, to support more than a million residents for a year.
Lund says the physical limitations of moving and handling surface water mean groundwater recharge projects cannot fix most of the state’s well problems.
“No matter how much (recharge) you do, you aren’t going to get more than 15% of the groundwater overdraft in the San Joaquin Valley,” Lund said. “That’s good, and you should do as much as you can economically, but you still have 80, 90% of the problem left.”
Gosselin, at the state water agency, is more optimistic, citing the new research, laws, funding and priorities in managing groundwater.
In the novel, East of Eden, John Steinbeck described Californians’ tendency to forget about wet times when it’s dry and drought when it rained. But Gosselin said growers and water agencies are now planning ahead, rain or shine, to capture and store water in the ground.
“We need resiliency from climate change,” he said, “…and I don’t think people are going to forget about either right now,” he said.