Beaver dam outburst floods prompt effort to protect Richardson Highway

A beaver dam created ponds that fueled a flash flood earlier this week when the dam collapsed, causing an outburst of water and debris that crossed the Richardson Highway near Paxson.

It was the second time in as many weeks that an outburst from the dam has closed the roadway.

The Alaska Department of Transportation and Public Facilities is now hoping to mitigate further road closures by digging out an area that will act as a catchall for debris in case the process repeats itself again, said Danielle Tessen, a spokeswoman for the transportation department.

Rocks, trees and other debris first rushed across the highway on the afternoon of July 1. The department initially called it a landslide, but Tessen said it was actually more of an outburst of water that released after the dam collapsed and flooded down the hill, carrying debris with it. Crews cleared the roadway the same day but returned less than two weeks later: The beaver dam on Monday night had again released and dragged debris across the highway.

Maintenance crews routinely encounter beavers that try to block culverts or other places where water is intended to flow through, but the landslide-like outburst is a new kind of problem, Tessen said.

The transportation department works alongside the Alaska Department of Fish and Game to address nuisance animals, said biologist Heidi Hatcher. There is a large population of beavers in the area near the landslide, she said.

The beavers living above the highway have already started rebuilding their dam, Tessen said Wednesday. While officials estimate that there’s a low risk that anyone could be harmed in a future outburst, Tessen said the department is trying to act swiftly to prevent another road closure.

“The likelihood of someone traveling at that spot at that moment isn’t super high, also because it’s an outburst not a landslide, so it’s over pretty quickly and it’s not a ton of material,” she said. “But it wouldn’t be good. Someone could get hurt, so that’s why we’re moving fast — there is an element of hazard.”

Officials are trying to determine exactly what parts of the land along the highway are owned by the state, and Tessen said they hope to be able to dig out an area downhill from the dam to catch debris that would fall the next time the dam collapses. Officials hope to know more by the end of the week but could look at purchasing land if it’s not state owned, according to Tessen.

It’s not immediately clear how much the project would cost. The goal, Tessen said, is to have the work done this summer.

The transportation department has an overarching permit that allows them to dispatch nuisance beavers during the offseason, Hatcher said. That’s not likely to happen at this point, however, because other beavers would likely move into the area and continue the problem, Tessen said.

“At this time, we have no plans of doing anything with the beavers, but what we are planning to do is just create the road to be safe, focusing on our infrastructure and ways to mitigate that whole thing from falling onto the road again,” she said. “The experience is that they just come back.”