From the late 1880’s to the early 1980s, the “Silver Valley” was the country’s largest producer of silver, lead zinc, and other metals. The mining and ore-processing methods used to extract silver, lead, zinc, and other metals produced large quantities of waste material containing toxic hazardous substances such as cadmium, lead, and zinc. Much of this material was discharged directly to, or washed into the South Fork of the CDA River and its tributaries.

In 1983, the US EPA listed the Bunker Hill Mining and Metallurgical Complex on the National Priorities List under Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), often referred to as the Superfund process. This site is in the heart of the Silver Valley and the Coeur d’Alene Lake basin.

As much as 83 million tons of particulate and dissolved metals from mining-related activities have been deposited into the lake since the 19th century. High flows moving through the Coeur d’Alene Basin every spring continue to deliver historic mining waste materials, sediment, and nutrients to Coeur d’Alene Lake. Lakebed sediments are highly contaminated with antimony, arsenic, lead, cadmium, zinc, copper, silver, and mercury throughout much of the lake*.

Authority to manage Coeur d’Alene Lake’s water quality rests with the Tribe, State, and Federal governments. However, authority to manage activities around the basin that impact water quality in the lake is the responsibility of many other local, state, federal agencies. Other partners include educational institutions, businesses, nonprofit organizations, and others.

Through close coordination of basin-wide activities with all parties, the Idaho Department of Environmental Quality (DEQ) and Coeur d’Alene Tribe (Tribe) are better able to understand program objectives, identify funding commitments and abilities to share costs or leverage additional funds, and reduce duplication of effort. Adaptive management is key, given the many land use issues to address and the need for possible solutions. For more information on what DEQ and the Tibe are doing to protect water quality in Coeur d'Alene Lake, please click on the DEQ and/or Tribal logo in the upper right of this screen.

* National Research Council of the National Academies (2005). Superfund and Mining Megasites: Lessons from the Coeur d'Alene River Basin. The National Academies Press. Washington, D.C.