Midnite Mine

Midnite Mine, located on the Spokane Indian Reservation eight miles from the Tribal complex in Wellpinit, is an inactive open-pit uranium mine closed in 1981, leaving behind 2.4 million tons of stockpiled ore (containing 2 million pounds of uranium oxide) and 33 million tons of waste rock. Two of the six excavated pits are open and partially filled with water. Exposed rock from the ore piles generate acid rock drainage. Radionuclides and heavy metals have contaminated groundwater, seeps and surface water, including Blue Creek.

Radionuclides of concern at the Midnite mine and in downstream watersheds include Uranium-238 decay series isotopes such as Uranium-238, Radium-226, Thorium-230 and Radon-222. Heavy metal contaminants of concern include: Aluminum, Arsenic, Barium, Beryllium, Cadmium, Chromium, Cobalt, Copper, Lead, Manganese, Molybdenum, Nickel, Selenium, Silver, Thallium, Uranium, Vanadium, and Zinc. The waste rock piles and the ore remaining in the open pits at the Midnite mine have significant sulfide content leading to acid generating conditions that release heavy metals and other pollutants into surface and ground water.

The Midnite Mine operated from 1955–1981 under the ownership of a subsidiary of Newmont Mining Company: Dawn Mining Company. Today the mine looks like an open wound in the heart of the Spokane Indian Reservation. Dawn abandoned the pits and 33 million tons of waste rock they created without conducting reclamation work to either rehabilitate the site or prevent release of pollutants. As a result, radionuclides, heavy metals and other pollutants have spread several miles beyond the mine site, leaving a toxic trail in downstream creeks and valleys and in downwind plants and hillsides in the central part of the Spokane Indian Reservation.

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