For over 100 years, the Coeur d’Alene River Basin (Basin) was one of the most productive silver, lead, and zinc mining areas in the United States, producing 7.3 million metric tons of lead and 2.9 million metric tons of zinc between 1883 and 1997. The majority of mining and mineral processing in the Basin occurred along the South Fork of the Coeur d’Alene River and its tributaries. The wastes generated by these operations contain metals, including lead, zinc, cadmium, and arsenic.

For most of the 20th century, these wastes were discharged directly into the river and tributaries or were deposited on lands and migrated into ground and surface waters. Mining products and wastes containing metals were also transported by train and other vehicles that spilled and tracked metals along travel routes in the Basin. Mining-related wastes were also taken from the mine and mill properties or hauled out of the floodplain areas for use in other applications throughout the Basin, including without limitation ballast for railroad lines, materials for street and road surfacing, and concrete aggregate. As a result, mining-related waste rock, tailings, mine drainage, and contaminated floodplain deposits are continuing sources of metals contamination in the Coeur d'Alene Basin. Tailings and contaminated sediments continue to be deposited in the Coeur d’Alene River channel, levees, and floodplain, as well as in lakes and wetlands adjacent to the river, and in Coeur d’Alene Lake. As a result, extremely elevated metals concentrations exist in soil, sediments, and waters throughout the Basin.

In 1983, the U.S. Environmental Protection Agency (USEPA) listed the Bunker Hill Mining and Metallurgical Complex Superfund facility on the National Priorities List (NPL) in response to human health risks associated with mining-related metals contamination in the 21 square-mile area around the former Bunker Hill smelter.