Midnite Mine Superfund Site | Region 10 | US EPA

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Midnite Mine Superfund Site

Midnite Mine is an inactive former uranium mine in the Selkirk Mountains of eastern Washington. Located within the reservation of the Spokane Tribe of Indians, the mine was operated from 1955 until 1981.

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Community Resources (contacts, fact sheets, meetings, comment opportunities)

Technical and Legal Documents

Maps and Photos

Contact Us:

Karen Keeley (keeley.karen@epa.gov)
EPA Project Manager

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Cleanup Design Progress

Dawn and Newmont (the mining companies involved with Midnite Mine) completed the final 100% Basis of Design Report in October 2015.

Public Health Assessment

A public health assessment conducted in 2010 by the federal Agency for Toxic Substances and Disease Registry (ATSDR) suggests that residents should not:

  • use water from seeps, drainages, or Blue Creek for drinking or sweat lodge ceremonies;
  • gather plants in or along mine drainages and Blue Creek in the mining-affected area;
  • consume fish from Blue Creek;
  • eat the organs, especially the liver and kidneys, from deer, elk, or other big game harvested in or near the Blue Creek drainage area.

ATSDR Public Health Assessment for Midnite Mine (PDF) (153 pp, 3.7MB) - May 2010

Aerial Radiation Survery of the Spokane Reservation

In September 2011, EPA conducted an aerial survey of the Spokane Reservation to follow up on questions about sources of radiation outside Midnite Mine. A small plane with ‘US EPA’ painted on the bottom of its wings, flew over the areas of interest at 500 ft above the ground. Equipment on the plane gathered data on radiation levels in various locations including populated areas, Midnite Mine, the Dawn Mill, and the Western Nuclear/Sherwood mine/mill.

Site Summary

Two open pits, backfilled pits, a number of waste rock piles, and several ore/protore stockpiles remain on site. In addition to elevated levels of radioactivity, heavy metals mobilized in acid mine drainage pose a potential threat to human health and the environment. The site drains to Blue Creek, which enters the Spokane Arm of Franklin D. Roosevelt Lake. Contaminated water emerging below the waste rock and ore piles is currently captured for treatment in an on-site treatment system.

After a study of the site, EPA sought public comment on a proposed cleanup plan in September 2005. The final cleanup plan for the site is described in the Record of Decision issued September 29, 2006.

The Record of Decision calls for a cap over an area of pits filled with waste during mining, consolidation and engineered containment of remaining waste in the two open pits, removal of water entering the pits, and operation of a treatment system to treat contaminated water from the pits and seeps.

Under a 2008 EPA order, Newmont Mining Co. and Dawn Mining Co. fenced the site and and performed initial design studies. Design work and site cleanup up continue under a legal agreement called a consent decree, finalized in January 2012.

Who pays for the cleanup?

EPA's policy is to have the responsible parties - also called Potentially Responsible Parties, or PRPs - pay for cleaning up pollution. Responsible parties can be past or present operators and land owners.

Under a legal agreement called a consent decree, Dawn Mining Company, LLC, and Newmont USA Limited will complete the cleanup work, and the United States will contribute a share of the cleanup costs. EPA will oversee the cleanup work in coordination with the Spokane Tribe.

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