Photo at right shows Middle Fork of the Boise River with toxic mine tailings sloughing into the river at the Monarch Stamp Mill Site.

The Monarch Stamp Mill Site is located near the town of Atlanta. The Site is along the Middle Fork of the Boise River and was used for milling silver and gold ore from about 1865 intermittently through the 1920's and 1930's and perhaps longer. The Site contains about 23,000 cubic yards of mill tailings along the river. Tailings deposits cover an area approximately 550 feet by 350 feet in area. The depth of tailings ranges from a few inches along the margins of the Site to over 10 feet thick. Arsenic and mercury (from gold processing) are the primary contaminants of concern. Tailings three to five feet thick are exposed in the cutbank of the Middle Fork of the Boise River. These tailings are a source for continued erosion and downstream migration during times of peak flow. Also, elevated levels of arsenic and mercury present a direct contact public health threat for recreational users of the Site.

This summer, Trout Unlimited is working with the Environmental Protection Agency to stabilize the banks of the river and pull back the tailings to an area beyond its reach. Stabilization techniques will include sensitivity to fish friendly designs. The resulting ³clean² riverbank will be revegetated by Trout Unlimited volunteers. By removing the hazard from the river and capping it, exposures should be minimized to both animals and people using the area.

Remnants of the Stamp Mill stone wall stand guard over the tailings below.

Questions or comments? tutedtrue@aol.com
Ted Trueblood Chapter of Trout Umlimited