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Record snows in the Blackfoot drainage driving current Missoula flooding

Posted at 3:57 PM, May 08, 2018
and last updated 2018-07-05 15:03:56-04

SEELEY LAKE – While attention right now is on the flooding impacts along the Clark Fork River in Missoula, hydrologists have some of their focus much further upstream, where they’re watching a record snowpack finally starting to melt.

Most of Missoula’s flooding problems are starting in the high country of the Blackfoot drainage, where places like the Swan and the backside of the Mission Mountains are still buried in snow.

“The Bob Marshall Wilderness, the Mission Mountains, some of the mountains that are over along the Continental Divide, just still a lot of water left to come out of those,” said National Weather Service Hydrologist Ray Nickless.

“We’re getting these surges of runoff coming out of the mountains and that’s what’s giving us our current flooding problems. But we still have a lot of water. The good thing is it’s not going to all come out at once. It’s going to be kind of a slow, continual process,” he added.

The amount of snow, and the water it will produce are very, very high. Places like the SNOTEL station in the Upper Jocko still have 10-feet of snow, waiting to release some 70-inches of water.

Streams all through the Seeley-Swan are swollen with runoff, and there’s still a surprising amount of snow on the ground north of Seeley, even down to 4,000 feet in elevation, where it’s still stacked under the trees and along the Forest Service roads…

“Depending on what elevation zone you’re in as far as what wilderness area you’re in, or what mountain range you’re in the snow’s pretty consistent,” Nickless said. “That lower elevation snow is pretty dispersed, depending on what slope of the mountain you’re looking at. What shaded areas you’re looking at. But still, a lot of water left in the system.”

That runoff is still flooding some yards along the Clearwater in Seeley, where residents were first swamped last week. But the real story is on the mainstream of the Blackfoot itself, where the “river that runs through it” has become the “river that roars through it”.

The Blackfoot is just now getting into minor flood stage and is expected to crest at 10.8 feet. It’s very impressive, but not enough to scare some thrill seekers.

While the Blackfoot is roaring right now providing most of the floodwater for the Clark Fork, that will start to change in a week or so, as more of the high country snows start to melt in the Upper Clark Fork Basin.

“The Upper Clark Fork really hasn’t started to accelerate its snowmelt yet. And we’re not expecting it to this week. That’s still later to come too, so,” Nickless said.

The record flood level on the Blackfoot is 16-feet which was set in February of 1996.

Reporting by Dennis Bragg for MTN News