Steamboat Springs The Yampa Valley shed a portion of its spring flooding concerns this week as streamflows in the Yampa and Elk rivers bounced above historic norms.
The increasing flows are a sign that low-elevation snowmelt finally is under way. The highest potential for runoff remains intact in the snowpack on the Continental Divide east of Steamboat Springs.
Routt County Emergency Management Director Chuck Vale said a cold April poses the biggest potential for flooding locally. A chilly April means there's a chance low-elevation snow won't run down the rivers until the high country melt-off also is under way. An overlap could flood riverbanks.
But the rivers are playing catch-up this week.
Heavy April snowfall here caught the attention of statewide water managers. Mike Gillespie, snow survey supervisor for the Natural Resources Conservation Service, told the Rocky Mountain News in an April 15 story that snowpack in the Yampa Basin had jumped from 107 percent of average to 120 percent of average.
"Before, we weren't that concerned about the Colorado and the Yampa. But now it's coming on strong," Gillespie told the Rocky Mountain News.
Both rivers languished below historic average streamflows April 16 through 19. But that trend reversed itself April 20, when the Yampa jumped above 600 cubic feet per second at the Fifth Street Bridge in Steamboat for the first time this spring.
April 20, coincidentally, is the date when the river typically begins to rise toward its peak in late May.
By Wednesday, the river had climbed to 1,300 cfs at the peak of its diurnal cycle.
Wednesday's reading by the U.S. Geological Survey showed the river at a full 500 cfs above its historic median flow of 833 cfs for the date.
The upper Elk River holds some of the densest snowpack in the region. The Elk, near its confluence with the Yampa, jumped dramatically April 19 from 600 cfs to 1,300 cfs. The next day, the river ran all the way up to 1,600 cfs. Despite the dramatic change, there is no indication of flooding. The river at that level still is 4 feet below flood stage.
The average streamflow at the mouth of the Elk on this date is 900 cfs.