It’s not the runoff yet, but area rivers setting March records

Pedestrians cross the Clark Fork River in downtown Missoula on Monday. The river was flowing at nearly 7,000 cubic feet per second, a record for March 20. The runoff is yet to come, hydrologists say. (Martin Kidston/Missoula Current)

By Martin Kidston/Missoula Current

Rivers and streams across western Montana were running high on Monday, with stream gauges managed by the U.S. Geologic Survey reporting new records for this particular day in March.

The water was high enough to prompt passersby to stop and take it in.

By midday, the Bitterroot River near Missoula was running at 6,730 cubic feet per second – more than double the record set for this day in 2015 when it hit 3,850 cfs. The Clark Fork below Missoula was listed at 13,200 cfs, also above the record set in 1972 when it reached 10,800 cfs.

“It’s something we’re not used to seeing in mid March,” said Ray Nickless, a hydrologist with the National Weather Service in Missoula. “We’re seeing that a lot of these river gauges are setting maximums for this particular day. There’s tons of location like that, and to see this much water at this time of year is very unusual.”

From the Bitterroot River near Darby to Lolo Creek, stream gauges all reported record highs. By the time the Clark Fork wanders up to Plains, gauges are measuring 39,000 cfs. That’s nearly three times the volume of water on the same river below Missoula.

Nickless attributed the high March flows to recent rain, with some areas along the Montana-Idaho border picking up more than two inches. Combined with warm temperatures and low-elevation snowmelt, the runoff gained momentum, pushing some rivers and streams toward flood stage.

“The areas that seem to be impacted the most, with damage of roads, were in northwest parts of the state, like Lincoln and Sanders counties,” Nickless said. “Mineral County has some water in those locations as well. While the rivers are high in some of these counties, like Ravalli and Missoula, we’ve heard of no damage in those locations.”

Nickless believes streamflows have likely peaked for the time being. Even with scattered showers predicted over the next week, the cooler temperatures should slow melting and keep the snowpack in place for a few more months.

But when temperatures do warm up, he said, the runoff should be impressive.

“We’re going to have good high water on our rivers for the rest of the spring, just because we’ve had so much moisture with a good snowpack at the middle and higher elevations,” he said. “We’ll see river flows higher than this in May and June when we get our runoff.”

Contact reporter Martin Kidston at info@missoulacurrent.com