to Wallace, Idaho, where it joins two large tributaries, Canyon and Ninemile Creek. Below Wallace, the valley broadens, the channel gradient begins to diminish, and the river increases in flow as it passes the Idaho communities of Osburn, Kellogg, Smelterville, and Pinehurst. Below Pinehurst, the South Fork joins the North Fork, and the valley widens to several miles, with the floodplain containing thousands of acres of wetlands and small lakes that provide a valuable stopping place for migratory waterfowl. Some 70 miles from its source, the river empties into the 25-mile-long Lake Coeur d’Alene, which in turn is drained by the Spokane River at its northern end.
In the late 1800s and through most of the 20th century, the upper and middle portions of the basin were a major mining region—the “fabulous Coeur d’Alene” (see Chapter 2 of this report). The area had more than 100 mines and ore processing operations producing silver, lead, zinc, and other metals. The Bunker Hill Mine and Smelting Complex, located in Kellogg, Idaho, was the largest of these, and, when the Bunker Hill smelter was built, it was the largest smelter in the world. The Coeur d’Alene mines produced and processed an estimated 130 million metric tons (more than 140 million U.S. tons) of ore during their first century of operation (Long 1998). Today, although a few mines continue to operate, most have closed; the smelting complex is shut down and most of its facilities have been demolished.
The mining, processing, and smelting of such a huge volume of ore resulted in widespread environmental contamination. Many of the mine tailings throughout the region were discharged directly to Coeur d’Alene River and its tributaries until 1968 when the practice was prohibited. Smelting operations at Bunker Hill also discharged large quantities of sulfur dioxide, lead, and other metals that affected local communities and the environment. During operation of the smelter—particularly in the early 1970s when its pollution-control devices failed—large numbers of nearby residents, especially children, had highly elevated blood lead levels (BLLs) (IDHW 1976). The wastes produced by the milling and processing operations pose risks to residents of the area and to the wildlife—particularly fish and migratory birds—that depend on the basin’s natural resources.
In 1983, EPA listed the Bunker Hill Mining and Metallurgical Complex on the National Priorities List (NPL).2 This site encompasses a 21-square-mile rectangular area (commonly called “the box”) surrounding the Bunker Hill smelter complex. The site was divided into two operable units (OUs):