midnite mine


Midnite Mine is an inactive open-pit uranium mine located on the Spokane Indian Reservation in rural Stevens County. Uranium-bearing rock exposed due to mining are a source of radiation, and acid rock drainage has mobilized heavy metals. EPA completed a Remedial Investigation/Feasibility Study and proposed a cleanup plan in 2005. The cleanup decision was documented in a Record of Decision in September 2006. Litigation to determine liable parties concluded in 2008. As of 2009, pursuant to a CERCLA order, the mining companies are continuing interim water management and performing pre-design studies, and they have installed a fence to restrict human and animal exposure. Negotiations for remedy design and implementation are in progress. Dawn Mining Company ("Dawn") developed Midnite Mine in 1955 and operated it until 1981. Newmont Mining Corporation ("Newmont"), a US mining conglomerate, holds the majority interest in Dawn. Ore was hauled off the reservation by truck for processing at Dawn's mill in Ford, Washington, 25 miles east of the mine. During mine operations, about three million tons of 0.2 percent uranium oxide ore, 2.5 million tons of low grade ore (protore), and approximately 33 million tons of waste rock were dug up from six pits. Waste rock was dumped in piles and used to backfill pits, build haul roads, and contour the surface. Today, unreclaimed piles of waste rock and stockpiles of ore and protore are visible on the more than 320 acres disturbed by mining. Two open pits contain water collected at several seeps (where water emerges at the foot of the largest waste rock pile), water flowing into the pit, and surface water runoff. The remaining pits are backfilled with waste rock from the mine. Since 1992, to reduce impacts to surface water, Dawn has been collecting seep water, pumping it to the open pits, and treating the pit water. The water is treated on-site and discharged, under an NPDES permit, to a surface drainage. Sludge from the water treatment process is taken by truck to the mill in Ford. Until recently, the sludge was processed to extract uranium and disposed of in a lined tailings disposal area, TDA-4. The mill license was modified in 1999 to allow the sludge to be disposed directly in TDA-4 without processing. The Washington Department of Health is overseeing closure of the mill under the Uranium Mill Tailings Radiation Control Act. The mill building was demolished in 2004, and other steps in the mill cleanup are planned or in progress. Studies by the U.S. Bureau of Mines and the U.S. Geological Survey documented that seeps, groundwater, and pit water at the mine are contaminated with heavy metals and radionuclides. In April 1998, EPA completed an Expanded Site Investigation (ESI), that confirmed elevated levels of metals and radionuclides in many on-site sources. Several seeps not currently captured by Dawn's collection system were found to contain elevated metals and radionuclides. These seeps and shallow groundwater emerge in drainages which lead to Blue Creek, which flows into the Spokane River arm of Lake Roosevelt. Blue Creek is an important spawning and nursery area for rainbow trout and other fish, including the Paiute sculpin, a species of special concern in the State of Washington. The site is also associated with Palustrine (marshy) wetlands. Site Responsibility: This site is being addressed through federal and potentially responsible parties' actions.

Hazardous Ranking Score

50 / 100

A score of 28.5 or higher qualifies a site for the Superfund National Priority List.

Regional Contact

Region 10
Phone: (800) 424-4372

Contact Region



Site Inspection
Preliminary Assessment
Final Listing On NPL

Contaminants & Health Effects

      Endocrine Disrupter
      Reproductive Toxin
      Persistent, bioaccumulative and toxic


        African American
        American Indian and Alaska Native
        Native Hawaiian


        People living
        within a 1 mile radius


        Average Income


        Occupied homes

        Potentially Responsible Parties

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