Ian James
The Desert Sun
NASA researchers have studied the aquifer beneath the Coachella Valley and concluded that while flows of imported water have helped boost groundwater levels in places, much of the aquifer has continued to decline.
Scientists with NASA’s Jet Propulsion Laboratory analyzed trends in the measurements of groundwater levels in wells between 1960 and 2013.
They found that inflows of water from the Colorado River have helped raise the water table in areas near groundwater replenishment ponds in Palm Springs and La Quinta, but that the aquifer’s levels have been falling across the middle of the valley, in places from Thousand Palms to Indio, Palm Desert, Rancho Mirage, and Indian Wells – areas that are farther away from the ponds.
The study was published online last week by the journal Water Resources Management. The scientific findings fit with the results of The Desert Sun’s analyses of groundwater data in 2013 and 2015, which showed significant long-term declines in water levels in much of the valley even as imported water has helped partially counteract that trend. The study points to a need for the Coachella Valley’s people, businesses and water managers to better safeguard the aquifer to preserve water supplies for the future.
Hydrologists Brian F. Thomas and Jay Famiglietti used data for more than 300 wells to compare trends in different decades.
During the 1980s, for instance, the area received large allocations of surface water, and as a result groundwater levels rebounded around Palm Springs. In the 2000s, the valley received little water and the aquifer’s levels predominantly declined.
For decades, water has been heavily pumped from wells across the desert to sustain growing cities, farms, more than 100 golf courses and lush resorts with acres of grass and artificial lakes.
Since the 1970s, the Coachella Valley’s water agencies have been using water from the Colorado River Aqueduct to help recharge the aquifer near Palm Springs. The water has come in exchange for the local water districts’ allotted amounts from the canals and pipelines of the State Water Project, which ends in Lake Perris and doesn’t reach the valley.
During the past decade, water from the Colorado River has also been routed through the Coachella branch of the All-American Canal to a series of ponds in La Quinta, pushing up groundwater levels there.
Despite those efforts, average groundwater levels are approximately 19 meters, or 62 feet, lower than in 1960, the scientists said in the study. They noted that during periods when large amounts of surface water have flowed into the area, groundwater levels have risen. But during drier times, such as the 2000s or the current drought, “unsustainable groundwater practices in the region resulted in groundwater declines.”
The changes in groundwater levels over time, they said, “fail to exhibit characteristics of a resilient management strategy.”
“The scenario of continued unsustainable groundwater use in a region that relies heavily on groundwater resources to meet water demands has important implications for the region,” the researchers said, “especially given the uncertainty in future climate changes and the likelihood of increased droughts… and the uncertainty of future allocations from the Colorado River.”
In short, Thomas said, the findings point to a need for people to use and manage water differently in the Coachella Valley.
“They need to conserve water,” Thomas said in a telephone interview. He said he thinks the Coachella Valley also should manage the aquifer as the area’s primary water source and not rely so heavily on outside sources of surface water as it has in the past.
The Colorado River provides water for more than 35 million people across the West and irrigates vast stretches of farmland from the Rocky Mountains to Mexico. But its flows have been shrinking during a historic drought that’s now in its 16th year. Global warming is projected to put additional strains on the over-tapped river by shrinking the snows in the mountains and unleashing more severe droughts.
Flows of water to Southern California through the State Water Project have also dwindled during the drought.
Thomas said the trend in the 2000s, when groundwater levels were declining across the Coachella Valley, is similar to the situation now.
“And I think that’s really the future of the Coachella Valley,” he said. “When you look at the uncertainty of climate in the Southwestern U.S. and the uncertainty of surface water allocations coming out of the Colorado River basin, I think the reality of the situation for the Coachella Valley is what they saw in the 2000s. … It was depletion throughout the valley.”
The study focused on “sustainable groundwater management” and didn’t deal with the question of how much water remains in the aquifer – something experts aren’t sure of because it hasn’t been studied in detail.
Water agencies have calculated the cumulative overdraft since the 1970s at more than 5.3 million acre-feet of water. That's enough to fill more than 2.6 million Olympic swimming pools, with each acre-foot equivalent to 325,851 gallons.
As groundwater levels have declined, there have been costs. Pumping from deeper underground requires more electricity, and in some areas new wells have been drilled.
A study by the U.S. Geological Survey last year found that as groundwater pumping has led to declines in portions of the aquifer, the ground sank from between 9 inches to 2 feet from 1995 to 2010 in parts of Indian Wells, La Quinta and Palm Desert. That has caused damage in other parts of the Coachella Valley over the years, cracking the foundations of some homes and damaging swimming pools, roads and other infrastructure.
The USGS found that the Coachella Valley Water District's efforts to recharge the aquifer are having a positive effect near the groundwater replenishment ponds in La Quinta.
“We have to give credit to the water agencies. They’re actually employing very smart strategies,” Thomas said. “It’s obviously having a positive impact on groundwater resources. It’s just that (the impacts) are not extensive when you look at the entire aquifer system as a whole.”
CVWD General Manager Jim Barrett said when contacted about the research that he had just learned of the study and couldn’t comment on the findings.
John Powell, Jr., president of the CVWD board, has said the agency is evaluating potential sites for new groundwater replenishment ponds in the middle of the valley in order to reduce pressures on the aquifer in that area.
The long-term declines in the aquifer fit with a larger trend of groundwater depletion in much of California, and in various parts of the world.
Famiglietti, a UC Irvine professor and senior water scientist at NASA's Jet Propulsion Laboratory, recently co-authored another study that found more than half of the world’s largest aquifers are declining, and more than a third of them are being rapidly depleted.
Thomas, a postdoctoral researcher at the California Institute of Technology, said he thinks that for the Coachella Valley, improving the water picture starts with coming up with ways to use less.
“If it were up to me, people would not have lawns in Palm Springs,” Thomas said. “Lawns, that’s something that is not necessary in a desert environment. And that’s just one of the things that’s key to a conservation strategy.”
In the acknowledgments in their study, the scientists credited The Desert Sun’s coverage “for alerting us about the growing concern over groundwater overdraft in the valley.”
Thomas spoke about his research last year to an audience at UC Riverside’s Palm Desert campus.
"There's no easy answer,” he said during the event. “Everybody has to give up a piece of their water use to get to sustainability."