Porcupine Landslide dams portion of Greys River

Three earthquakes and unseasonable rain caused the Porcupine Landslide about 17 miles outside of Alpine, Wyoming in early February. The 25-acre landslide wiped out about a quarter mile of Greys River Road and has dammed up a portion of the Greys River. The Bridger-Teton National Forest Service is concerned about the dam retaining a large amount of water and additional materials going into the river bed. This would cause it to dam off the river faster and make the situation worse.

“The number one fear is if that dam breaches in a rapid fashion, you’d have a massive amount of water heading down stream,” said Mike Oltman, an Engineering and Mineral Staff Officer for Bridger-Teton National Forest. “17 miles towards the town of Alpine.”

However, Oltman says the risk to the town of Alpine is low. There is a risk to two houses in low-lying areas that could face a potential threat, but that too is low. The forest service is also concerned about what will happen once the snow begins melting.

“Once you add the mass of all the moisture we have around here into an already unstable soil, it’s almost certainly gonna come down and continue to move into the Greys River and dam it to a further height than we currently are impounding,” Oltman said.

Some have questioned whether the forest service can do anything right now to prevent further damage. They say there is not much they can do.

“One of the key reasons that we can’t bring equipment or blasting in to try to clear the river channel because there’s a high probability that if we took any action at the tow of the slide it can make the situation worse and not better,” Oltman said. “And then we could be putting houses and families at risk which is our number one priority to make sure that we don’t do that.”

Part of Greys River road is damaged and the area is currently closed.

“The biggest priority is working towards reopening this road and opening a bypass route if it’s possible,” Oltman said. “We have absolutely no intention of closing the Greys River Road. We’re gonna do everything we possibly can to re-open the road as quickly as we possibly can this coming season.”

The Bridger-Teton National Forest Service has tentatively received emergency funding from the Central Federal Lands Emergency Relief for Federally Owned Roads program. They have also applied for an additional $4 million in funds to put toward fixing the damage from the landslide.