From Arizona Geology Blog:
The U.S. Environmental Protection Agency added the Iron King Mine - Humboldt Smelter site in Dewey-Humboldt, Ariz., to the federal Superfund list today, after its initial proposal in March. [right, Iron King mine tailings, Humboldt, AZ. Credit, wikipedia]
This brings the number of Superfund sites in Arizona to 9.
According to EPA, "the site encompasses areas of contamination from two facilities: the Iron King Mine property and the Humboldt Smelter property. The Iron King Mine was an active mine from 1904 until 1969. The majority of this area is covered by tailings and waste rock piles.
The Humboldt Smelter is situated less than one mile east of the Iron King Mine property. The smelter operated from the late 1800s until the early 1960s. This area is covered in yellow-orange tailings, grey smelter ash, and slag. Mining and processing have contaminated soil, sediments, surface water and groundwater with arsenic, lead, and other metals."
The listing had the endorsement of the AZ Dept. of Environmental Quality.