Massive landslide on Wind River west of Union Pass Road creating a new lake; River now in a narrow channel
(Dubois, Wyo.) – A massive landslide is creating a lake on the Wind River just west of the Union Pass Road and the Albright Sand and Gravel operation west of Dubois.
“We do have an anomaly with a slide coming into the Wind River, we’re monitoring it, engineers are putting their eyes on it and at this point they don’t know how to fix it,” Sheriff Skip Hornecker told the Fremont County Commissioners on Tuesday. He said the slide had occurred on private property.
The slide was discovered over the weekend and had narrowed the river to the point that water had begun backing up behind the slide and was threatening a private residence. “It is continuing to move and my staff have seen it move from just inches to a foot at a time. We may end up with a Wind River reservoir.”
Hornecker said the area around the slide is very dangerous. “I had a deputy and another person up there putting eyes on it and suddenly the bank collapsed under the deputy, the other man was able to grab him and pull him to safety.” The sheriff has urged residents in the area not to try their own fix, due to the danger, but several landowners have attempted to slow the slide and free timber from creating a dam.
County Transportation Department Supervisor Dave Pendleton said the river at the site is 30 feet wide, but the slide is constricting it to about 7 feet from the opposite bank. “The water is being forced into a narrow channel and a lake is forming behind it,” he said.
Hornecker said the slide appears to be about 100 yards in width. “It’s massive, so the river just can’t wash it downstream. The sheriff said WYDOT Geologists and Bridge Engineers are investigating, along with other civil engineers in the area. He said the U.S. Army Corps of Engineers had been notified, “but they don’t seem to be concerned.”
Hornecker said the ground in the area had been saturated by the heavy snowfall over the winter and spring and he said it appears water flowing downhill above the slide, at 15 to 20 gallons per minute, was flowing into the top of the slide apparently keeping it moving. He said the top of the slide was hard, but there was a waterlogged area underneath that was slipping.
“If it does break loose, there is a large flood plane downstream and the sand and gravel pits, which could fill up. I had fears if it had blown out, Dubois could’ve been inundated with a 10 to 20 foot wall of water.” The sheriff said the water is finding a course through the slide that sloughed off into the river, and he hoped that would wash some of the slide away and ease the problem. The slide has also covered a headgate for an irrigation canal that serves one hayfield.
He said the slide is being monitored continuously.