Kennecott North Zone sits in the Oquirrh Mountains near Magna, Utah, and has operated as a copper mining and processing facility since 1906. The U.S. Environmental Protection Agency (EPA) proposed the site to the National Priorities List (NPL) in January 1994. The NPL is the federal list of the most serious uncontrolled hazardous waste sites in the country. The site is divided into nine operable units, each targeting a specific geographic area or type of contamination problem.
The main contaminants are arsenic, copper, lead, selenium, and sulfate. They appear in groundwater, soil, sediment, and solid waste across the site. Mining and ore processing spread these metals into nearby wetlands and surface water as well. Groundwater migration is not currently stabilized, meaning contaminated groundwater continues to move beyond its original area. Human exposure pathways have not yet generated reliable enough data to confirm whether people are being exposed to unsafe levels.
Rio Tinto Kennecott has led cleanup under a 1995 agreement with federal and state regulators. The 2002 cleanup plan called for treating contaminated surface materials, followed by groundwater treatment and removal of inaccessible mining wastes after the facility eventually closes. Work completed so far includes in-place treatment of selenium-contaminated groundwater, demolition of unneeded buildings, removal of contaminated soil, and storage of excavated material at the Arthur Step-Back Repository. For Operable Unit 8, which covers the wastewater treatment plant area, EPA selected bioremediation, monitoring, and offsite disposal in its September 2002 Record of Decision. The Third Five-Year Review, completed September 30, 2024, found that cleanup for certain operable units is not yet fully protective of the environment, with ongoing concerns about arsenic and selenium in groundwater and potential effects on birds in nearby wetlands.
In October 2025, EPA released an updated Lead Directive that lowers the blood lead level of concern and changes soil screening levels at Superfund sites. Lead poses particular risks to children under seven and pregnant or nursing women. The site team is evaluating how this directive affects cleanup decisions at Kennecott North Zone. Several operable units, including the Great Salt Lake and Associated Wetlands unit, are still in early study phases, with remedial investigations scheduled to run into 2027.
Community members can get involved by contacting EPA's Community Involvement Coordinator. The Utah Department of Environmental Quality also has a Community Involvement Specialist available. EPA has stated that cleanup decisions will be based on site-specific information and community input.
