The Bruno Creek Tailings Impoundment is a tailings dam on Bruno Creek, southwest of Challis in Custer County, Idaho. It serves to store tailings for the nearby Thompson Creek Mine. At tall, it is the second tallest center-line tailings dam in the world. In 2008, Phase 8 of the mine was approved which includes a raising of the dam to . The dam is mainly composed of cycloned sand. Currently, the dam stores of tailings and the raise would increase storage to . The downstream slope of the dam will be steepened from 3:1 to 2.75:1. In 1994, it was discovered that acid mine drainage had been forming on the embankment since 1987. Since seepage does occur at the dam, a system of wells was installed to monitor groundwater and a seepage return dam was constructed downstream. References Dams in Idaho Tailings dams Buildings and structures in Custer County, Idaho Dams completed in 1983 Mining in Idaho