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Lewis & Clark County: Beaver dams in Tenmile Creek contributed to flooding

Posted at 8:20 PM, May 17, 2018
and last updated 2018-07-05 14:56:45-04

HELENA – Lewis and Clark County public works leaders have been looking for ways to address the ongoing flooding in the Helena Valley. This week, they say they identified one surprising factor contributing to the issue – beavers.

Public works director Eric Griffin and his crew walked along the banks of Tenmile Creek, from Green Meadow Drive to McHugh Lane.

“We found a couple spots where there had been some beaver activity in there that was forcing the water out of the Tenmile channel down to the north,” he said.

Griffin said they worked closely with the Montana Department of Fish, Wildlife and Parks to determine how to deal with the beaver dams. The owners of the surrounding land gave the county permission to bring in an excavator. Crews then broke down the dams, over a period of several days.

“We didn’t want to release more water down Tenmile and get people wet that have not been wet before,” Griffin said.

Once the Tenmile channel was cleared, Griffin said much more water was able to flow downstream toward Lake Helena – and less has flooded nearby areas.

“It has made a huge difference in what’s going on in the Valley at this point,” he said.

Griffin said the county always has to be concerned about beaver dams during flooding.

“They raise hell in culverts; they back the water up and then it affects our roads,” he said. “They’re busy beavers – there’s a lot of activity out there.”

Many of the flood-related road closures in the Helena Valley have been lifted, but the county is still restricting traffic on Sierra Road, McHugh Lane and Mill Road.