Author Description

In July 2004, at the request of Pam Gardner, District Ranger for the Pleasant Grove District of the Uinta National Forest, Ed Harp of the U.S. Geological Survey (USGS) conducted a preliminary assessment of the rock-fall hazard at Little Mill campground in American Fork Canyon, Utah. The campground has had a history of rock-fall activity and lies immediately east of a former U.S. Forest Service (USFS) picnic site (Hanging Rock picnic area) where two people were killed by separate rock-fall incidents in the mid-1990s. Harp's preliminary assessment of rock-fall hazard at the campground indicated that parts of the campground were located immediately downslope from active talus chutes and that rock from some previous falls had traveled through the campground and across the adjacent American Fork River. Harp concluded his preliminary assessment with the recommendation that a detailed assessment of rock-fall hazard at the campground be conducted using a combination of field- and aerial-based methods. The USFS funded the USGS to conduct this detailed hazard assessment in October and November, 2004. This report describes the methodology, results, and conclusions from the detailed hazard assessment.