High Potential For Landslides In Northwest Wyoming

May 31, 2019

Wittke, S.J., and Stafford, J.E., 2019, Susceptibility to deep-seated landslides in Wyoming: Wyoming State Geological Survey Open File Report 2019-7, scale 1:850,000.

Wyoming has had a very wet spring due to all the snow and rain. The increased amount of moisture caused many rock falls, landslides and mudslides blocking roads in the state, especially in northwest Wyoming.

One example is the rock slide near the Buffalo Bill Reservoir just outside of Cody. The rock and debris were captured by a fence completed last year that was part of a recently completed two-year project. But because it has been such a wet spring, the ground saturated and loose rocks were able to get free.

"We didn't know that we were going to have upwards of four to six inches of water content in May which led to saturate soils. It just causes things to move," said Cody Beers with the Wyoming Department of Transportation.

But he said the fencing did do its job.

It turns out, northwest Wyoming has a high potential for rock falls and landslides compared to the rest of the state. According to a new study released by the Wyoming State Geological Survey, this region has rocks sitting on steeper slopes and rocks that are also usually just on the subsurface.

And according to a new study which looked at the susceptibility of landslides in the entire state, northwest Wyoming has a higher potential than the rest of the state.

"The way they [rocks] are on the subsurface makes them a little more prone to landslides where in other parts of state you may have less steeply dipping rocks, which would make them a little less susceptible," said Seth Wittke with the Wyoming State Geological Survey, the group that published the study.

Wittke said it's normal for more landslides and rockfalls to occur in the spring because that's when the ground is very saturated.

Most roads have been cleared and reopened, but, if parts of the state gets summer temperatures in the next few weeks, there's a potential for lowland flooding impacts.