RAPID CITY, S.D. (AP) - New devices have been inserted deep underground at the recreation area in the Wyoming portion of the Black Hills National Forest to monitor landslides.
Data from the devices is relayed to the smartphones of U.S. Forest Service employees, who can order an evacuation when conditions indicate the potential for a fast-moving landslide or mudslide, the Rapid City Journal (https://bit.ly/2sVyLt4) reported.
Black Hills National Forest geologist Karl Emanuel said there are numerous slow-moving landslides near Cook Lake, but one in particular on the forested hillside above the lake’s southwestern shore is being monitored.
He said if the 40-acre area’s movement accelerates, it could partially fill the lake with millions of tons of earthen debris or release a dangerous torrent of liquefied earth known as a mudslide.
“It’ll eventually come down into the lake,” Emanuel said. “You can’t stop a landslide.”
Nobody knows whether that’ll happen today or hundreds of years from now. In the meantime, the Forest Service has closed the potentially threatened parts of the recreation area while the rest of the site remains open to public use.
Cook Lake is in the Bear Lodge Mountains, approximately 30 miles west of Spearfish. The 30-acre lake is only open to non-motorized use and was created by a dam built in 1941 on Beaver Creek.
Several large landslides occurred at the lake during the 1900s. The most recent was in 1997, when part of a slope rising nearly 300 feet above the southwestern shore of the lake collapsed. It formed a chasm near the hilltop and pushed up a mound of earth along the lake shore.
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Information from: Rapid City Journal, https://www.rapidcityjournal.com
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