Trustees Settle Natural Resource Damage Claims Arising from Hazardous Substances Releases at Morenci Mine, Greenlee County, Arizona

Last edited 09/25/2020

Morenci Mine site in Greenlee County, Arizona
The Morenci Mine site, near Clifton, in Greenlee County in southeastern Arizona, includes operational features such as open pits and tailings impoundments, as shown here in 2008, that released hazardous substances causing injuries to natural resources. Photo credit: Arizona Geological Survey.

On June 29, 2012, the U.S., on behalf of Department of the Interior, and the State of Arizona settled natural resource damage claims with Freeport-McMoRan Corporation arising from hazardous substances releases at the Morenci Mine, an open-pit copper mining site near Clifton, Greenlee County, in southeastern Arizona. This settlement is embodied in a Consent Decree that was entered with the U.S. District Court for the District of Arizona.

The natural resource trustees in this case include:

  • State of Arizona, represented by Department of Environmental Quality; and,
  • Department of the Interior, represented by Bureau of Indian Affairs, Bureau of Land Management, Bureau of Reclamation and U.S. Fish and Wildlife Service.

Altogether, the Morenci Mine site includes a large complex of open pits, numerous leach rock stockpiles, development rock stockpiles, ore and solution beneficiation plants, tailings impoundments, uncovered ponds, five historic smelters, historic underground mine workings and surface openings. Surface water flows from the site drain into the San Francisco River and Gila River watersheds.

The trustees determined that hazardous substances releases from and at the mining site -- including sulfuric acid and dissolved metals such as arsenic, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, selenium and zinc -- have caused injuries to natural resources and natural resource services. These hazardous substances were released through acid rock drainage, process solutions, windblown material, waste material and other sources. Injured natural resources include surface water, sediments, soils, terrestrial habitats, terrestrial receptors and migratory birds.

Under the final settlement in the entered Consent Decree, Freeport-McMoRan will:

  • Pay $6,701,861.30 to be used by the natural resource trustees to plan and implement projects designed to restore, replace and/or acquire the equivalent of wildlife and wildlife habitat inured by the hazardous substances releases; and,
  • Pay $98,138.70 for DOI’s past assessment costs not already paid.

DOI has already been reimbursed $842,483.80 for past cooperative assessment costs.

The natural resource trustees, acting through a Trustee Council that will include Arizona Game and Fish Department, will prepare one or more Restoration Plans describing how these funds will be used for natural resource restoration activities. These future Restoration Plans will be made available for public review and comment.

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