Porcupine landslide may threaten Alpine
The Porcupine landslide on Greys River Road near Alpine, Wyoming is continuing to slide down the hillside and into the flood plain. It affects about a quarter mile of the road (FS Road 10138) and could pose a threat to the town.
Bridger-Teton National Forest officials said there is potential for the slide to create a natural dam on the Greys River. Several state and federal agencies are monitoring the slide’s movement. The teams are modeling for potential flooding if a natural dam were to form and fail and assessing its potential threats to the town of Alpine.
“We are concerned due to the number of unknowns presented by the landslide moving down the hillside into the Greys River and have requested assistance from specialists from around the State,” said Greys River District Ranger Justin Laycock. “We have analysis team members from the U.S. Army Corps of Engineers (USACE) Walla Walla District assisting, and several agencies are building hydrologic models to assess any potential flooding risks posed by the slide,” he said.
The forest and the State of Wyoming have begun to develop contingency plans specific to the Town of Alpine after hydrologic modeling has been compiled and analyzed.
A temporary closure has been ordered around the landslide area. Although the Alpine access is closed 17-miles in from the parking lot, visitors still may access the Forest beyond the closure by three other routes. They include the Smith’s Fork Road (Forest Service Road 10072) located South of Afton. The second route is through forest service access from Big Piney, WY (proceed to Ryegrass Junction to Forest Service Road 10125, also known as N. Cottonwood, then over McDougal Gap to Greys River Road) and 93). And, the La Barge Road can be accessed from the town of La Barge, Wyoming.
The Forest has also identified a temporary, non-groomed, over-snow route for public access up and around the slide area from Alpine. That bypass is not recommended for inexperienced snowmobilers.
