StoryMap: The Past, Present, and Future of US Magnesium
US Magnesium LLC is a facility on the southwest shores of Great Salt Lake that began extracting magnesium from the Lake's brine in 1972. The facility has a fraught history of toxic releases to surrounding air, water, and communities. It was designated an EPA Superfund Site in 2009 but continued to operate until 2022.
For decades, FRIENDS has been working to hold US Magnesium accountable for its impacts to Great Salt Lake's ecosystem. Through a Technical Assistance Grant from the EPA, we hire a technical advisor to oversee the Superfund process at the site, which includes monitoring the hydrological and ecological happenings at the facility. We report these findings (below) to the public and state and federal regulators to advocate for remediation and accountability.
In December 2024, the Utah Division of Forestry, Fire and State Lands notified US Magnesium that it was cancelling the company's mineral lease, followed by a cease and desist order in the summer of 2025 demanding that the company stop pumping water from Great Salt Lake. In response, the facility filed for bankruptcy for a second time, seeking to escape its legal and financial liabilities.
Determining how the mess will be cleaned up and by whom requires additional action and study of the US Magnesium Superfund Site by state and federal agencies.
FRIENDS has compiled decades of oversight into a new StoryMap to help our community understand and engage in this complex issue.
Click here to view the StoryMap full screen, or scroll through the embedded version below.
Scientific Monitoring & Reports
What's Next Analysis
Since 2013, FRIENDS has overseen cleanup of the US Magnesium Superfund site through a Technical Assistance Grant from EPA (see background below for more information). The purpose of the TAG is to inform members of the public of the threats posed by the Superfund site as well as what needs to be done to address those threats.
With that charge, we asked our Technical Assistant Grant advisor, Dr. Bill Johnson, to summarize the most immediate threats existing today, as well as his recommendations regarding the actions needed to understand the extent of those threats.
Read the summary report below:
What’s Next Analysis of the US Magnesium Superfund Site
By William P. Johnson, TAG Advisor to FRIENDS of Great Salt Lake
Published on 09-18-2025
Key Points:
- Though US Magnesium has not been operational since 2022, contaminants from the site still pose a significant threat to human and ecosystem health.
- Dr. Bill Johnson's risk assessments demonstrated that human carcinogenic risk and risks to birds, mammals, and benthic invertebrates drastically exceeded regulatory benchmarks.
- There is evidence that groundwater pathways have transported and continue to transport contaminants away from the site.
- The need to further understand the area’s hydrology and the extent of contamination is urgent, especially because the containment wall around the waste pond has not been completed.
- Recommended action steps:
- Review of existing documents to assess contamination in CERCLA portion as existed during operation.
- Resampling of well hydraulic heads and retrieval of samples for analysis of selected contaminants in wells to understand changes in groundwater flow and current contaminant concentrations.
- Installation of additional piezometers for sampling of hydraulic head and contaminants at five to ten sparsely monitored zones on perimeter of older Waste Pond and beyond.
- 3D modeling of contaminant transport conditioned to current hydraulic head and contaminant concentrations to simulate likely transport scenarios for contaminants outward from the site.
Proposed Assessment of Contaminant Transport and Remediation at the US Magnesium Superfund Site
Four steps are outlined above to determine the extent to which contaminants have moved, are moving, and could continue to move, outward from the US Magnesium site. The document below is a proposal and budget to accomplish those steps in the geohydrologic framework as currently understood from previous work. The total budget for this proposed work is $213,300. Read the full proposal below:
Proposed Assessment of Contaminant Transport and Remediation at the US Magnesium Superfund Site
By William P. Johnson, TAG Advisor to FRIENDS of Great Salt Lake
Published on 10-07-2025
2025 Summary of US Magnesium Site Conditions
This summary updates previous analysis with new information from barrier wall contractor, Forgen. Specifically, Forgen provided diagrams showing precisely where the barrier wall had been completed and notched into the underlying clay layer. It also expands the analysis via consideration of relative concentrations detected for waste water tracers. This analysis is intended to further guide monitoring efforts to constrain the extent of contamination to groundwater.
By William P. Johnson, Professor, Department of Geology & Geophysics University of Utah
Published on 12-08-2025
Legacy Groundwater Pollution from Unregulated Discharges
With the US Magnesium facility currently idled, some have suggested that the barrier wall that was designed to protect Great Salt Lake from the extensive contamination of groundwater beneath US Magnesium's unlined waste ponds is no longer needed. We disagree with that suggestion in the strongest possible terms. When FRIENDS was selected in 2013 to receive a Technical Assistance Grant from EPA to oversee the Superfund process at US Magnesium, one of the first tasks for our TAG Advisor, Dr. Bill Johnson, was to sort through an avalanche of documents describing the extent of the problem. There are reasons why the site was placed on the Superfund list by EPA, and one of those reasons was the clear evidence in documents generated by EPA that 40 years of essentially unregulated discharges left a legacy of pollution in groundwater that was headed towards the Lake. That legacy still exists today and still poses a substantial threat to the Lake's ecosystem. To remind stakeholders about the documented extent of the contamination that exists beneath both the Current Waste Pond (CWP) and the Old Waste Pond (OWP), we're posting the documents below which summarize an analysis of that contamination:
2016-2017 Annotated Bibliography
Notes from Final OWP-CWP HydroCSM Annotated Bibliography
2017 Hydrogeologic Report: Groundwater Discharge Permit Application – Part C
Additional Background
Click to read more.
US Magnesium has been a significant presence on the southwest shore of Great Salt Lake in Tooele County since 1972. The facility harvests brine from the Lake to produce pure magnesium, alloy magnesium, magnesium chloride, lithium, and chlorine. As the largest domestic supplier of magnesium in the United States, US Magnesium is important to the defense, technology, and food industries.
In the 1990's, when known as Magcorp, the facility gained notoriety as the nation's worst air polluter for two consecutive years. This led to the formation of Citizens Against Chlorine Contamination (CACC), a coalition including FRIENDS of Great Salt Lake (FRIENDS), Sierra Club, and others. Following a federal lawsuit, Magcorp filed for bankruptcy protection, significantly reduced emissions and rebranded as US Magnesium in 2002.
The facility as viewed from across their evaporation ponds in Stansbury Bay. Image by Doug Tolman.
According to recent data, US Magnesium depletes a substantial amount of water through its evaporative processes, averaging about 43,800 acre-feet per year from 2017 to 2021. This makes it the second most consumptive water user on Great Salt Lake. This significant water use, primarily through evaporation ponds, has been a critical point of concern for FRIENDS, especially as water levels remain below the target healthy range of 4,198-4,205’ ASL as designated by the Great Salt Lake Commissioner’s Strategic Plan.
EPA Superfund Cleanup
Throughout the early 2000’s, the Environmental Protection Agency (EPA) sought to list US Magnesium as a site of National Priority - commonly referred to as a Superfund site. US Magnesium sued to prevent being added to the National Priority List (NPL), with the district court ruling in their favor. The EPA appealed the case to the 10th district court of appeals, who then ruled in favor of the EPA. In Fall 2009, the EPA, supported by the Utah Department of Environmental Quality (DEQ), listed the US Magnesium facility and its surrounding waste disposal areas as a national priority for cleanup. This opened up additional resources, processes, and community involvement opportunities to clean-up the site. Given the site's proximity to Great Salt Lake, FRIENDS has closely followed developments in the Superfund process, including taking the initiative to apply for and be awarded a Technical Assistance Grant (TAG) from EPA. With theTAG, FRIENDS hired a Technical Advisor to advise us on the sufficiency of the cleanup effort and to assist in communicating the technical aspects of the cleanup to our community and stakeholders. This role helps facilitate community participation in the decision-making process. The cleanup addresses various environmental concerns, including potential water contamination, soil and sediment pollution, air quality issues, wildlife impacts, and worker health risks. As part of the information obtained during the TAG process, it became clear to FRIENDS that there was a significant hazardous groundwater plume beneath the company’s unlined wastewater ponds from illegal discharges to groundwater by US Magnesium. Based on this information, FRIENDS pressured DEQ to require US Magnesium to obtain a groundwater discharge permit and address the problem. As a result, US Magnesium was issued a notice of violation and is being required to construct a containment system to limit groundwater contamination into Great Salt Lake. The proposed system consists of an underground barrier wall measuring approximately 5 miles in length and 40 feet in depth, connected to the Bonneville clay layer believed to underlie the entire site. Though the concept for this barrier was submitted to the EPA in 2015, as of September 2024, construction of the barrier wall has not yet begun. This containment system is a crucial component of both US Magnesium's groundwater discharge permit and their settlement with the EPA regarding Superfund site cleanup.
Canal Extension Permit Denial
In 2022, US Magnesium proposed a controversial project to dredge and extend its intake canals by 3.7 miles into Great Salt Lake. This would have allowed the company to pump up to 100,000 gallons of water per minute from the receding Lake. FRIENDS took the lead in raising awareness about this proposal and its potential environmental impacts with both the US Army Corps of Engineers (USACE) and DEQ. As a result, DEQ received over 800 public comments in opposition to the project, overwhelming their capacity to respond in a timely manner. Our efforts, along with those of other environmental groups and concerned citizens, contributed to both USACE and DEQ's decision to deny US Magnesium's permit application. Among other things, the agency cited insufficient information about potential impacts on water quality as the reason for the denial.
US Magnesium plant with overlays of the denied canal extension and future barrier wall. Image by Doug Tolman.
Continuing Discussion
The history and impacts of the US Magnesium facility are long and seemingly endless. For years, the various entities who own and manage this site have stepped in the way of efforts to mitigate their impacts to air quality, water quality, and the health of Great Salt Lake. It's urgent that the barrier wall construction is completed and other monitoring and clean-up measures are implemented. Though the future of this facility is uncertain, FRIENDS remains committed to closely monitoring US Magnesium's activities and advocating for responsible practices that don’t further harm the Great Salt Lake ecosystem.
