Department of
Environmental Quality

The cleanup area in the Basin is any place where mining-related contaminants have come to be present.

Lead, arsenic, zinc and cadmium remaining in tailings and other mine wastes are referred to as "contaminants." Contaminants from historical mining in the Silver Valley area were found in Coeur d’Alene Lake and the Spokane River system to about 60 miles downstream. An estimated 62 million tons of mine wastes were dumped directly into the South Fork of the Coeur d’Alene River and its tributaries between 1884 and 1968.

Cleanup actions are determined by the Records of Decision (ROD) issued by EPA in a public involvement process. RODs are legal documents that determine the cleanup actions for the Site. Currently, the RODs are divided into three cleanup areas called operable units.

 The cleanup is divided into the following three areas:

• Operable Unit 1 = populated areas of the Bunker Hill Box (Box). This 21-square-mile area was addressed first because of the high levels of contaminants in soil and in blood lead levels in humans.  
• Operable Unit 2 = non-populated, non-residential areas of the Box.
• Operable Unit 3 = areas of mining-related contamination in the South Fork and main Coeur d’Alene River watersheds including Coeur d'Alene Lake and the Spokane River to Upriver Dam in Washington state.