Big snowpack, warm temps in Aspen mean higher river flows
A spate of warm weather predicted for the next several days is likely to prompt high flows for this time of year in the Roaring Fork River and other area waterways, forecasters and river watchers said this week.
That’s because the snowpack in the high country remains huge for this time of year, said Valerie MacDonald, Pitkin County’s emergency manager.
“It’s mind-blowing,” she said Thursday. “It still looks like winter in a lot of places.”
A June 20 National Weather Service model of the snowpack — which was the last snowpack forecast of the season — shows most of the high country around Aspen and in Colorado between 200% and 500% above normal. And that was before last weekend’s snowstorms came through.
“We do expect (the Roaring Fork) to come back up again,” MacDonald said. “We want the public to be aware that the rivers are high, fast and cold. It’s not the time for an extended swim in the river.”
High temperatures in the Aspen area are expected to remain in the high 70s and low 80s for the next several days, according to forecasts.
On Thursday, the Roaring Fork River at Stillwater Bridge east of Aspen was running at about 400 cubic feet per second, said April Long, Clean River Program manager for the city of Aspen. The river is expected to rise to between 600 and 650 cfs in the next three days or so and remain at about that level for the next week, according to predictions by the Colorado Basin River Forecast Center.
And while that is roughly the river’s historic level at about this time of year, generally the rivers are decreasing in flow now rather than rising, which is what’s happening, according to Long and historical data on the CBRFC website.
“(The Roaring Fork) will be higher than normal because it’s going up,” she said.
Greg Smith, senior hydrologist with the CBRFC, agreed with Long.
“We’re expecting flows to rebound but they will not be as high as the peaks that occurred previously,” Smith said. “Next week through the (Fourth of July) the peaks will probably be around 700 (cfs).”
The river peaked above Aspen on June 21 at about 900 cfs, he said.
Smith said he expects higher flows in the river through “a good part of July” because of the large snowpack.
Several variables affect how much water is in the river, Long said.
Those factors include how warm it gets, how quickly temperatures rise, whether water is being diverted to the front range from Grizzly Reservoir and, eventually, the monsoons, she said.
“We could see bigger flows with rain on snow,” Long said.
The Twin Lakes Reservoir and Canal Co., which owns Grizzly Reservoir and operates the diversion tunnels underneath Independence Pass that send water to the Front Range, has not yet decided if and when it will stop the diversions, MacDonald said.
“They will keep us appraised of releases,” she said.
The flows in the Roaring Fork will be even bigger downstream after the confluences of Hunter Creek, Maroon Creek, Castle Creek and the Fryingpan and Crystal rivers, Smith and Long said.
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Mountain Rescue Aspen is expanding its education efforts to try to keep people safe in the backcountry during winters and summers. It will host a workshop on Dec. 8 titled, “How to Plan a Backcountry Tour.”