U.S. Magnesium

Overview

U.S. Magnesium sits on a 4,525-acre property in Tooele County, Utah. Magnesium production began there in 1972, and the facility has also operated under the names Magcorp Magnesium Corporation of America and U.S. Magnesium LLC. EPA added the site to the National Priorities List (NPL) in November 2009 after finding widespread contamination in soil, groundwater, surface water, and air. Two on-site businesses currently employ 698 people and generate about $155 million in annual sales.

The site contains heavy metals, acidic wastewater, polychlorinated biphenyls (PCBs), dioxins and furans, hexachlorobenzene (HCB), and polycyclic aromatic hydrocarbons (PAHs). These contaminants have spread into the air, soil, surface water, and groundwater. They pose both cancer and non-cancer health risks to people and wildlife. A 2024 Baseline Ecological Risk Assessment found dioxins to be the primary risk to birds and mammals, with additional concerns from metals, PCBs, and HCB in certain areas. Snowy plovers and other wildlife face elevated risks in upland and lakebed zones.

EPA split the site into two operable units. One covers soil, sediment, and water across the full property. The other addresses air quality within a five-mile study area. Sampling across all zones, including the heavily contaminated acid waste lagoons and gypsum piles, was completed in 2016. U.S. Magnesium has entered multiple enforcement agreements with EPA. Those agreements require containment measures, spill remediation, replacement of unlined ditches with underground piping, construction of a groundwater barrier wall, and compliance with air pollution controls. A Consent Decree was finalized in June 2021, and removal work under EPA oversight is estimated to finish between June and August 2027. A combined remedial investigation and feasibility study is estimated to begin between September and November 2026.

Human exposure is not under control, meaning unsafe contamination levels exist and people could reasonably be exposed. Groundwater migration is also not under control. No cleanup remedy has been selected yet, and physical construction of the full cleanup is not complete.

Community members can get involved through several channels. EPA finalized a Community Involvement Plan in 2012. Friends of the Great Salt Lake received a Technical Assistance Grant (TAG) from EPA in 2013 to hire an independent technical advisor who helps interpret site data for the public. They can be reached at https://www.fogsl.org/. EPA has also held informational meetings and community advisory group sessions with key stakeholders. Site records are available at Grantsville City Hall, the Utah Department of Environmental Quality (DEQ) in Salt Lake City, and the EPA Superfund Records Center in Denver. Copies of administrative records can be requested by calling 303-312-7273 or 800-227-8917 extension 312-7273.