June 20, 2019 / 5:36 PM / 2 months ago

In warming West, Rio Grande roars back to life, for now

TAOS, N.M. (Reuters) - After years of drought, no one in Rio Grande County, Colorado, can remember the last time their namesake river was closed to the public because it was running too high.

Strong run-off on the Rio Grande river is shown south of Pilar, New Mexico, U.S., June 19, 2019. Picture taken on June 19, 2019. REUTERS/Andrew Hay

But after the deepest snowpack in over two decades, topped off by a “bomb cyclone” spring storm in the Rockies, the raging, snowmelt-fed river has been shut to recreation in two Colorado counties.

The Rio Grande’s revival after one of its lowest years on record has brought relief to Indian pueblos, farmers and water managers along its course from the Colorado Rockies to the Gulf of Mexico. However, the future of the United States’ third-longest river, and that of other Southwest rivers, remains clouded by a warming climate.

Colorado rafting company owner Joel Condren is looking forward to an epic season this year, following 2018 when he could not open his business because the Rio Grande was too low.

This year he has the opposite problem, with the river running at up to 8,040 cubic feet per second at Del Norte, the greatest amount since 1985, according to Colorado state data.

“Right now we can’t fit under the bridges,” said Condren, 51, who operates 8200 Mountain Sports in South Fork, Rio Grande County, near the river’s San Juan Mountains headwaters.

FEAST OR FAMINE

The health of the 1,900 mile (3,058 km) Rio Grande reflects broader trends across the U.S. Southwest, where rising temperatures and lower snowpacks since the turn of the century have made droughts more severe.

Reduced snowmelt runoff threatens endangered species like the Rio Grande’s silvery minnow, starves farmers of water allotted through century-old treaties, and in the case of Arizona’s Lake Mead which is fed by the Colorado River, threatens water shortages in California, which relies heavily on the reservoir.

Migrants have long crossed the river, whose course forms much of the U.S.-Mexico border. Its swollen flows have led to a spike in rescues and drownings during the current surge of Central American families entering the United States from Mexico, where it is known as the Rio Bravo or “fierce river.”

The river has a “feast or famine” cycle, with a wet year typically helping it recover from dry periods.

Strong precipitation and unusually low temperatures this year have boosted soil moisture and pulled a vast swathe of the region, straddling Arizona, Utah, Colorado and New Mexico, from extreme or exceptional drought, according to the U.S. Drought Monitor, a U.S. government map showing the intensity of drought across the country.

But it would take years of similar snowfall to recharge reservoirs brought to near-record lows.

“The long term, decadal-scale drought conditions are not necessarily over,” said David Gutzler, professor of earth and planetary sciences at the University of New Mexico.

A BLIP?

Having fallen to 3% of capacity in 2018, New Mexico’s Elephant Butte Reservoir may hit around 30% in a couple of weeks, before being drained for irrigation, said U.S. Bureau of Reclamation water operations supervisor Carolyn Donnelly.

The last time the Rio Grande-fed reservoir was full was in the mid 1990s.

“Until we get repeated years of high flow, it’s difficult to build up a storage pool,” said Donnelly, whose agency manages dozens of reservoirs across the U.S. West.

Slideshow (2 Images)

Driving lower snowpacks and rainfall has been an average temperature rise of 2 degrees Fahrenheit in the region over the last 50 years. Temperatures are expected to keep rising over the course of this century. How high they will go depends on policy decisions about fossil fuel emissions, said Gutzler.

For now, hydrologists like Tony Anderson are enjoying the wetter conditions after documenting low-moisture levels and high temperatures that sparked some of Colorado’s worst ever wildfires in 2018.

“There’s been an incredible hydrological recovery since January,” said Anderson, with the National Weather Service in Pueblo, Colorado. “This could very well just be a blip in the long dry stretch we’ve been in.”

Reporting by Andrew Hay in Taos, New Mexico; Editing by Phil Berlowitz

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