ALBUQUERQUE, N.M. (AP) — Federal water managers warned Wednesday that like other basins across the western U.S., the Pecos River Basin in New Mexico is likely to experience growing water shortages as temperatures continue to rise over the next century.
The U.S. Bureau of Reclamation discussed the findings of a recently completed study on the basin during a virtual briefing, saying the goal of the work was to better understand the threats to water supplies in the region due to climate change. Officials also looked at what tools could be used to stretch resources to help sustain viable agriculture over the coming century as challenges grow.
Reclamation Study Manager Dagmar Llewellyn said those challenges are significant. She described the Pecos basin as arid with a limited and highly variable water supply.
“Drought and climate change-induced aridification is ongoing already in the basin,” she said. “We’ve been seeing less snowfall in the headwaters and more winter precipitation falling as rain. We’ve also been seeing higher consumption rates within the agricultural system.”
The peak flow of snowmelt runoff into Santa Rosa Reservoir, located at the top of the system, amounted to only a trickle of about 5 cubic feet per second this year. Total volume during the runoff period was about 700 acre-feet, or 56 times less than the historical average. That meant less water for downstream users.
About 80% of the basin's water goes to agriculture.
Other concerns include having enough water in the system to support threatened species and meeting delivery obligations to users in Texas as part of a water-sharing compact and a court settlement.
Rather than worry about the uncertainty of projections about the future, the study focused on a series of storylines about how the basin might evolve. Water managers then imagined how water uses could change as a result.
“We're not really dealing with the uncertainty question or trying to find the most likely future," Llewellyn said. "We're developing these different sandboxes that we can play in to see how we might behave, how we might use water, how we might modify our infrastructure, our operations under different potential future conditions.”
A number of factors were worked into the models used for the study, from irrigation shortages and endangered species considerations to water releases for Texas.
Officials said a decrease in future supplies won't necessarily mean a cut in agricultural production. Irrigation and infrastructure improvements, the use of more greenhouses, changes in the kinds of crops that are grown and other programs like water banking could be used to offset shrinking supplies.
Some irrigation districts already have been making changes. In Fort Sumner, real-time flow measurement devices and an automatic head gate have been installed. Other agencies are working on collecting more data to help with decision-making down the line.
Officials acknowledged that population growth in Roswell, Carlsbad and other communities along the Pecos River in eastern New Mexico could impact future demands, but the study didn’t evaluate domestic wells or potential changes in those over time.