ALBUQUERQUE, N.M. -- For about a mile, a steady stream of water flows down Bear Canyon before finally petering out in the sand near a golf course. The arroyo is not supposed to be wet this time of year; the spring snowmelt does not usually occur until later in the season. But under a new demonstration program, local water managers are diverting water from the Rio Grande and sending it down the arroyo, where it seeps through the riverbed into the aquifer 500 feet below.
If all goes according to plan, the water percolating underground will provide a sort of water savings account for the city of Albuquerque to draw upon during times of drought.
"You put a little in each year, and then one year, when there isn't enough water in the river, you can take it out of the aquifer," said Stephanie Moore, manager of the Bear Canyon Recharge Demonstration Project, this week while standing along the banks of the arroyo.
The new $400 million project to tap the water will eventually supply up to 90 percent of the Albuquerque metropolitan area's drinking water needs.
"It could be very important for us," added John Stomp, manager of the water resources program for the Albuquerque-Bernalillo County Water Utility Authority.
The move toward artificial aquifer recharge signifies a shift in thinking about water supplies in the West. Just a few decades ago, "people thought they were sitting on a huge lake, and that we'd never run out of water," Moore said. Then, after hydrologists found that overpumping was depleting aquifers, water managers began to look to surface waters like the Rio Grande to supplement dwindling resources.
The Bear Canyon water comes from the San Juan-Chama Project, which pipes water from the Colorado River Basin across the Continental Divide to the Rio Grande Basin. Moore, a hydrologist with the consulting firm Daniel B. Stephens & Associates, which is overseeing the project for the water utility authority, said flows from the San Juan-Chama project currently provide more water than is needed for immediate use, so the extra water is routed to the aquifer.
"We have more water to divert than we have demand for," she said.
While the Bear Canyon project is a first for New Mexico, the artificial aquifer recharge concept is gaining momentum across the country. Utilities and water managers from Florida to California are increasingly relying on recharged aquifers to help maintain water supplies during periods of drought.
"The trend has picked up," said Moore, who worked as a hydrologist for the U.S. Geological Survey before joining Daniel B. Stephens & Associates.
In some places, such as Florida, aquifers are routinely recharged in the winter, then tapped in the summer when water demand exceeds supply. But in other areas, geologic constraints and the need for long-term storage have led water managers to view aquifer recharges and withdrawals as a last resort.
In Nevada, for instance, there are restraints on how much water one can draw from an aquifer in a given year without causing subsidence of the ground above, said J.C. Davis, a spokesman for the Southern Nevada Water Authority, which serves the Las Vegas metropolitan area. The authority has stored an estimated 350,000 acre-feet in the aquifer underlying the city.
"It's a good long-term resource. We view it as a savings account -- we'll use it as we encounter specific needs," Davis said.
Nevada is augmenting its in-state aquifer storage with a water "bank" in neighboring Arizona, as well. Under a deal signed in 2004, Nevada pays Arizona $330 million to store up to 1.25 million acre-feet of water from the Colorado River for its northern neighbor (Land Letter, Dec. 9, 2004). Nevada can take up to 40,000 acre-feet of the water each year as long as the Lower Colorado River Basin is not facing a shortage.
In Albuquerque, water officials hope the Bear Canyon pilot project, which is funded by a grant from the state of New Mexico, will demonstrate that infiltrated water from the Rio Grande can recharge the overpumped Middle Rio Grande Basin aquifer and effectively store water for use in times of drought.
According to the monitoring data, the project sank about 750 acre-feet of Rio Grande water into the aquifer during its second run, from Dec. 11, 2008, to this week. The project's first run funneled about 400 acre-feet into the aquifer.
Cities typically store water in reservoirs, but in arid states like New Mexico, 10 to 15 percent of that water is lost to evaporation, Moore noted. Storing some of the water underground reduces that loss to about 3 percent, and shields it from the vagaries of the elements.
"Surface water is renewable [because of snowmelt], but it's highly variable and affected by drought and climate change," unlike water stored underground, Moore said.
But whether the water can be withdrawn in places like New Mexico has yet to be determined. A withdrawal permit is still under review by the New Mexico State Engineer John D'Antonio, who regulates water use in the state. He will likely make his determination after reviewing a report summarizing the data culled from the Bear Canyon project's monitoring wells over the past two seasons.
Moore acknowledged that the project's outcomes remain uncertain. "They're risking their water," she said of the Albuquerque-Bernalillo County Water Utility Authority. "There's a chance they won't be able to take it back out."
But Stomp, the utility manager, remains optimistic.
"Bear Canyon has been a tremendous success," he said. "I can't imagine that he wouldn't allow it. I think it makes really good sense for New Mexico to do this."
Stomp is also thinking about future potential aquifer recharge sites in other areas of the city, including a former gravel pit that could potentially store up to 30,000 acre-feet of river water. There, however, water would be injected into the aquifer via wells instead of being filtrated through a streambed.
"We're going to have to continue to come up with innovative ideas if we're doing to address these huge water challenges the West has," Stomp said.
April Reese writes from Santa Fe, N.M.
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