Snowpack in Southwest Colorado has bottomed out, marking one of the region’s earliest snowmelts in the last 30 years with warm and windy weather, dust and climate change to blame.
Snowpack in the San Miguel, Dolores, Animas and San Juan basins sat at 0.1 inches of snow-water equivalent, a measure of snowpack, as of Tuesday, according to SNOTEL data from the U.S. Department of Agriculture’s Natural Resources Conservation Service.
Since 1987, only 2002 and 2018 have had snowmelts this early, with snowpack reaching zero on May 22 and May 26, respectively.
The San Miguel, Dolores, Animas and San Juan basins sat at 5% of normal snowpack as of Tuesday, according to SNOTEL data.
This year has been a contrast to 2002 and 2018 because snowpack was about average while the other two were poor snow years, said Russ Schumacher, the Colorado state climatologist and an associate professor of atmospheric science at Colorado State University.
“It was the combination of the warmth, the sun, the wind and the dust all working together to take what was a fairly decent snowpack and melt it off really fast,” Schumacher said.
On average, snowpack finishes melting in Southwest Colorado on June 19, almost a month from now, according to SNOTEL data.
A number of factors are behind the melt, including warm and windy weather that stirred up dust.
April 2022 ranked as one the top 20 warmest Aprils in the last 128 years for much of La Plata County, and in the top 35 for much of Southwest Colorado, according to the Colorado Climate Center’s monthly climate summary.
Parts of Montezuma, La Plata, Archuleta, Dolores and San Juan counties also experienced one of their 10 driest Aprils on record.
Along with warm weather and limited precipitation, robust winds helped to expedite the snowmelt.
“(Wind) sublimates the snow. It basically evaporates the snow right off of the snowpack and it goes into the atmosphere, so that reduces the snowpack available for runoff,” said Steve Wolff, general manager for the Southwestern Water Conservation District.
In addition to melting the snow directly, winds also carried more dust from the Southwest, depositing it in the San Juan Mountains where it then increased the intensity of solar radiation and melted the snow faster, said Gigi Richard, an instructor of geosciences at Fort Lewis College and the director of the Four Corners Water Center.
Compounding the wind and the warm and dry conditions was climate change.
“It’s hard to say in any one year definitively this is because of climate change, but I think we’re seeing a very clear trend,” Richard said. “The warmer-than-average temperatures, it’s not every day, every month, every week. Over the longer term, there is a trend toward increasing temperatures.”
An early melt dries the landscape faster. With the reflective power of the snow gone, the soil traps more of the sun’s energy, increasing evaporation and transpiration and shuffling more water into the atmosphere.
“Once the snow is gone then the ground surface can absorb more solar radiation and usually things start drying out then,” Richard said. “Usually, an earlier loss of snowpack and earlier runoff correlates to lower total volume of runoff.”
With a drier landscape, wildfires, particularly bigger fires, become more of a risk, making the monsoon season in July and August especially important, Schumacher said.
Ken Curtis, general manager for the Dolores Water Conservancy District, said the early snowmelt will have minimal impact on the agricultural producers who rely on McPhee Reservoir for water because the reservoir captures the runoff no matter the time.
“For us with a reservoir, we don’t think the impact is too significant,” Curtis said, noting that those irrigators who divert their water directly from rivers will feel the effects most.
An average year of snowmelt has boosted McPhee from 8% last year to 25% this year. Farmers in the northern part of the district will receive 5.4 inches of water compared with 2 inches last year, Curtis said.
Elsewhere, Lemon Reservoir was forecast at 60% of average and Vallecito Reservoir at 63%.
The Colorado Basin River Forecast Center projected 60% of average for the Animas River and 72% for the San Juan River near Pagosa Springs.
The Animas River was running at about 1,150 cubic feet per second Tuesday afternoon after reaching 2,971 cfs on May 16.
The rapid loss of snowpack has not triggered an immediate response from the city of Durango, said Jarrod Biggs, assistant finance director and former assistant utilities director for the city.
In its Municipal Drought Management Plan, the amount of snowpack rather than the timing of snowmelt triggers the city’s water conservation restrictions. The city, which relies on surface water primarily from the Florida River, uses reservoir levels as well as other metrics to determine the implementation of restrictions.
“As of now, I think it may call for us to start doing what’s called ‘Stage 1’ and that’s really just internal exercises to make sure we’re pumping (and) make sure we’re working to maintain our reservoir level up at the treatment plant,” Biggs said. “As we move through the summer, that’s when I would expect those (water conservation measures) to ratchet up.”
Any water restrictions will depend on the other metrics the city uses as a guide, he said.
Wolff cautioned using SNOTEL data as the only information source for melting snowpack, pointing out that the number of SNOTEL sites is finite and each site measures snowpack at only one location.
In total, the NRCS relies on 20 monitoring sites to measure snowpack in the San Miguel, Dolores, Animas and San Juan basins.
Efforts are underway in the Dolores and Animas watersheds to use remote sensing technologies from airplanes and satellites to more accurately estimate the remaining snowpack and the water left in that snowpack, Wolff said.
However, Wolff said the earlier shift of snowmelt has been a clear trend.
“Earlier runoff is something we’ve been seeing for the last 10 to 20 years through this long-term drought,” he said.
While Southwest Colorado’s system of reservoirs will help mitigate some of the impacts, Schumacher said the disappointment of this year’s snowmelt is that early season storms and snow totals last winter looked promising.
“It’s just another rough snow season played out a little differently than some of the last couple of years did,” he said. “What we needed was a big year, another 2019 with lots and lots of snow that staved off the drought impacts for a while, but that’s not what we got this winter.
“It’s especially disheartening after all the hope that was there from the big storms in December and January,” he said.
ahannon@durangoherald.com
