ASPEN — Flows in local rivers are peaking this week, with a spring runoff that is slightly earlier and lower than normal.
“It kind of depends on where you are, but on the Colorado (River’s) main stem, for sure, the peak is below average,” said Cody Moser, senior hydrologist with the Colorado River Basin Forecast Center in Salt Lake City.
But despite the lower-than-average flows, this weekend is probably one of the best of the year to go boating on local waterways.
Vince Nichols, owner of the Aspen-based rafting company Blazing Adventures, said this weekend’s relatively big water is akin to a powder day.
The company is running trips on the upper Roaring Fork River, especially the Slaughterhouse section between Cemetery Lane and Woody Creek, and doing so in accordance with Pitkin County-mandated social-distancing and cleaning guidelines due to the COVID-19 pandemic.
“This will likely be one of the high-water weekends of the year,” Nichols said. “For the next seven to 10 days, there will be really good rafting conditions on the Roaring Fork.”
Flows in the Roaring Fork, at its confluence with the Colorado in Glenwood Springs, are predicted to be 74% of average for April through June. According to stream gauges, the Roaring Fork appears to have hit its peak seasonal flow on June 2 at just over 4,000 cubic feet per second. The normal period for peak runoff at this location is between May 29 and June 23, at about 5,900 cfs.
Predicting the exact day of peak flows near Aspen is trickier. The forecast center is predicting a peak for the Roaring Fork in Aspen on Saturday, at 490 cfs, because of rain expected that day. The Roaring Fork at Mill Street was running at a daily high of about 330 cfs on Thursday.
There would be more water flowing through Aspen if not for the Twin Lakes Tunnel, which takes water from the Roaring Fork headwaters near Independence Pass to Front Range water providers. About 600 cfs of water from the upper Roaring Fork basin was being diverted through the tunnel Thursday.
“The challenge is we’ve got that big warmup and precipitation in the forecast in this weekend,” Moser said. “It’s kind of a tough call.”
The low runoff, despite a snowpack that was slightly above normal, is due to 2019’s dry late summer and fall, plus this year’s drier-than-average March, April and May. Dry soils and plants sucked up a lot of the moisture before it made its way into the streams.
According to the U.S. Geological Survey gauges, the Crystal River near Redstone appears to have peaked on June 2, at about 1,750 cfs. The Crystal at this location usually peaks between May 25 and June 18, at about 1,930 cfs.
Downstream on the Colorado, flows peaked in DeBeque Canyon, above Grand Junction, on June 2, at about 13,300 cfs. A typical peak is about 17,000 cfs between May 24 and June 12.
This year’s peak flows on the Colorado near Grand Junction were augmented by releases from several upstream reservoirs to the benefit of endangered fish in the 15-mile reach between Palisade and the Gunnison River, which flows into the Colorado in central Grand Junction.
Beginning May 29, Green Mountain Reservoir, Wolford Mountain Reservoir, the Moffat Tunnel and other water-storage facilities released water to enhance the Colorado’s natural peak in the 15-mile reach. The augmented high flows enhance fish habitat.
Ruedi Reservoir, above Basalt on the Fryingpan River, did not participate in the coordinated reservoir operations this year because there was not surplus water to contribute, said Tim Miller, a hydrologist with the Bureau of Reclamation who manages water levels in Ruedi.
“I was getting kind of worried about fill a month ago,” Miller said. “I was pretty sure we didn’t have extra. We haven’t received anything near average precipitation for part of April or all of May.”
Ruedi Reservoir, which can hold 102,373 acre-feet of water, is currently 79% full. Releases from Ruedi will decrease Friday to allow it to fill, bringing flows on the Fryingpan to 115 cfs. Miller said it could end up about 5,000 acre-feet short of filling this year, which usually happens in early July.
Aspen Journalism is a local, nonprofit and investigative news organization that covers water and river issues in collaboration with The Aspen Times and other Swift Communications newspapers. This story ran in the June 5 edition of The Aspen Times.