A solid snowpack hit by unseasonably warm temperatures means western Montana rivers are rapidly swelling and broadening their banks—with big implications for anglers, boaters and firefighters.
“Right now, this warm weather we’re having, it’s been anywhere from 10 to 15 degrees above what we would say is average, and that’s bringing the snow melt out of the mainly lower to middle elevations, anywhere from 4,000 to 6,000 feet,” says Ray Nickless, a hydrologist with the National Weather Service in Missoula. “That water is bringing up the stream flows so that they’re following at above average flows in most locations in western Montana.”
The National Resources Conservation Service reported earlier in April that statewide snowpack was 100 percent of average. The lower Clark Fork and Bitterroot rivers were at 95 percent and 105 percent, respectively.
“It all depends from here how it rolls off the hills,” says fishing guide Russell Parks of the Missoulian Angler. “If we get a nice long and slow warming and cooling up and down over the spring here, and it comes off more normally, like last year, we’ll be in great shape for the season. If it comes off like two years ago, where we had a wonderful snowpack and it got hot and blew everything off quickly, we’re back to low flows real early.”
This week, Clark Fork River streamflows recorded above Missoula were in the 90th percentile, or about 175 percent of average, compared to historical flows, according to U.S. Geological Survey data. The Bitterroot River near Darby was around 165 percent of average.
Nickless says as long as spring warm spells don’t persist too long before the inevitable heat of the summer, the snowpack will last, keeping streamflows up late into the summer. But that wouldn’t necessarily bode well for fire season.
“An even more critical thing for fire [conditions],” Nickless says, “is rain—if we can we get some rain in the spring here, in May and June, and help things green up but not get too hot.”