Climate change is likely to render a key part of the water supply for Santa Fe and Albuquerque increasingly unreliable in coming decades, according to a new analysis by federal scientists.
The San Juan-Chama project, which imports water from the mountains of Colorado for use in New Mexico’s most populous cities, is likely to see shortfalls in one of every six years by the 2020s, and four out of every 10 years by the end of the century, according to researchers at Sandia National Laboratories and the U.S. Bureau of Reclamation.
The study comes as federal officials are warning that for the first time in the project’s 40-year history, the San Juan-Chama project may not deliver a full water supply in 2014. Whether the current shortage is a result of climate change or natural variability is uncertain, but this year’s shortfall could be “a harbinger of things to come,” the study’s authors wrote.
The study is part of a collaboration between federal researchers and the city and county of Santa Fe intended to provide a detailed look at the possible impact of climate change on that community’s water supply.
“It’s prudent planning,” said Claudia Borchert, the city of Santa Fe’s water resources coordinator.
The San Juan-Chama analysis is one piece of a larger study, to be completed later this year, that looks at all of Santa Fe’s water supply sources, including groundwater, runoff from the Sangre de Cristos and the Rio Grande itself.
Because Albuquerque also gets water from the San Juan-Chama project, officials with the Albuquerque Bernalillo County Water Utility Authority are watching its results closely.
“Any loss of San Juan-Chama water is a huge deal,” said John Stomp, chief operations officer for the Albuquerque water agency.
Studies have repeatedly shown that water supplies in the western United States, including on the Rio Grande and Colorado River, are at risk as rising greenhouse gases change the region’s climate, driving temperatures up and precipitation down.
The new analysis by hydrologists Jesse Roach at Sandia Labs and Dagmar Llewellyn at the Bureau of Reclamation represent the first attempt to take those general findings and apply them specifically to the San Juan-Chama project.
The federal project diverts water from the mountains of southern Colorado through a series of tunnels beneath the Continental Divide. It allows New Mexico’s populated central valley to use some of New Mexico’s share of the waters of the Colorado River Basin.
With river water and groundwater outstripped in recent decades by water demand in the Rio Grande Valley, the San Juan-Chama water has become an increasingly important backup supply, especially for Santa Fe and Albuquerque. The communities have separately spent hundreds of millions of dollars to build water treatment plants and distribution systems to deliver San Juan-Chama water to their customers.
But both communities’ water agencies have already run into problems using the water, as drought and fire damage to Rio Grande watersheds have made it harder to use because of low river flows and ash-laden flows during the heat of summer, when it is needed most.
One possible future problem, Roach and Llewellyn found, is that climate change may make it more difficult for the Bureau of Reclamation to capture the precipitation that falls in the headwaters that feed the San Juan-Chama project. Rapid runoff, caused by warm temperatures or warm rainstorms falling on snow, may make water come off the mountain too quickly for the project’s dams and tunnels to catch it all.
But that also suggests that there may be technological solutions to part of the problem, said Mike Hamman, head of Reclamation’s Albuquerque office. Upgrades to the tunnel and dam infrastructure might be possible to capture more of the rapid runoff, Hamman said in an interview.