Call it the flood that wasn’t.
In Basalt, homeowners were stacking up sandbags. In Glenwood Springs, a trailer park owner hacked down trees along the Roaring Fork River. After a winter of heavy snows, valley residents were preparing for an onslaught of runoff from the high country.
But a cool spring that left residents longing for summer created nearly ideal conditions for a slow runoff that had area rivers running high but remaining within their banks.
River watchers say they’re reluctant to declare the threat of flooding has passed, but it would take hot days combined with a heavy localized downpour to raise the danger again.
“I don’t want to say we’re completely done,” said Brenda Alcorn, senior hydrologist with the National Weather Service’s Colorado Basin River Forecast Center. “There’s still high water out there. But there’s really not enough snowpack to bring the flows up much without a big rain event. I think the flows will continue to be above normal for the time of year throughout the month, but I think the threat of snowmelt flooding has pretty much passed.”
The snowpack above Independence Pass was at 118 percent of average at the beginning of July, according to the Natural Resources Conservation Service. That means plenty more snow to slow down hikers in the high country, and plenty more water to fill area rivers.
Ruedi Reservoir, on the Frying Pan River above Basalt, was about 5 1/2 feet shy of the top, more than 90 percent full, and was expected to reach capacity by mid-July. The gradual spring runoff has kept Ruedi releases normal, rather than forcing dam operators to release more water to keep the dam from filling too fast.
“If it had just gotten warmer and warmer and warmer, there wouldn’t have been that cooling off to help (the runoff) slow back down,” said Kara Lamb, spokeswoman for the U.S. Bureau of Reclamation, which operates the dam.
The dam has been releasing about 550 cubic feet per second of water in recent days, Lamb said, and were it not there, the river would have gushed at about 2,400 cfs for three weeks straight last spring.
“That’s a lot of whitewater,” she said.
Communities along the area’s rivers had been preparing for flooding throughout the spring. A flood team from Basalt, Aspen and Pitkin County had been meeting since February to prepare to respond to high water. Basalt had bought sandbags and 30 tons of sand to shore up low-lying areas. Most went unused, said Basalt Town Manager Bill Efting, and none was needed, although more than 600 sandbags were put in place at Old Pond Park to protect irrigation systems and landscaping.
Both of Basalt’s mobile home parks loaded up with sandbags. So did some neighborhoods close to the rivers. The trailer parks saw groundwater rise, but the sandbags were never needed. “I don’t think there’s any doubt that we dodged a bullet with the way the weather worked out,” Efting said.
Area officials worried that a hot spring could mean a fast, heavy runoff that could have rivers spilling over the banks and threatening low-lying residences. When the spring turned out to be cool and the runoff slow, they worried instead that it could be too slow, and that more snow would pile up in the mountains, meaning an even heavier runoff when summer finally came.
“Everybody was running a little bit scared when the snowpack was building up there,” said David Kanzer, water resources engineer with the Colorado River Water Conservation District based in Glenwood.
Instead, the forces of nature conspired to bring a gradual runoff, with periods of warm weather alternating with cool phases.
“As soon as we started to build to a crescendo in terms of heat, all of a sudden a cold front would come in and cool it off,” Kanzer said. “Instead of coming to a peak, we had a long, broad, flatter peak.”
Peak river levels probably came and went in the end of June, Kanzer said. But river levels remain high, and there’s more runoff, and possibly more storm water, to come.
“There is still quite a bit of snow up in those watersheds, but the biggest event we’re likely to face would be a thunderstorm event that could cause local flooding at any time, unrelated to the snow,” Kanzer said. “The snow would be influenced by a rapid and long-term, protracted heat wave, but, even so, most of that snow has come off to the point that we’re probably in a good situation.”
dfrey@aspendailynews.com