US Magnesium, once named the country's top air polluter, has been added to the Environmental Protection Agency's Superfund priority list, which will help accelerate cleanup of toxins at its facility on the edge of the Great Salt Lake.

The designation announced Monday and done with the support of the Utah Department of Environmental Quality means cleanup of a host of toxins at the nation's only remaining magnesium-processing plant will fall under federal and state purview.

"The benefits of this designation extend well beyond the boundaries of the US Magnesium facility," said Gwen Christiansen, EPA's national-priorities-list coordinator in Denver. "The removal and containment of site contaminants will reduce health risks for those that work in the area and will directly benefit wildlife, water quality and the overall health of the Great Salt Lake ecosystem."

US Magnesium officials did not return phone calls from the Deseret News on Monday seeking comment on the designation.

The 4,525-acre site in Rowley, Tooele County — about 40 miles from Salt Lake City — has produced a variety of toxic wastes from its production of magnesium. Established in 1972, the plant uses brine from the lake in its manufacturing process, which has given rise to a variety of contaminants. The EPA says those toxins include heavy metals, acidic wastewater, polychlorinated biphenyls (PCBs), dioxins/furans, hexachlorobenzene (HCB) and polycyclic aromatic hydrocarbons (PAHs). These contaminants pose cancerous and non-cancerous health risks to humans and wildlife and have been released into the air, soil, surface water and groundwater, according to the EPA.

Of particular concern, the agency noted, is that the levels of pollutants are substantial enough to potentially pose health risks to workers throughout the site.

In addition, because the Great Salt Lake plays host to millions of migratory birds, evidence of contamination to waterfowl and their eggs has heightened the need for cleanup.

The EPA says birds have been regularly observed in contact with or near contaminated areas on the site and likely die after exposure. Bird-egg studies have also documented concentrations of PCB and HCB in all eggs at or near the site. In the past, high water levels in the Great Salt Lake have flooded the site, creating an open conduit for contaminants to travel into the lake, according to the EPA.

The designation means US Magnesium is eligible for extensive, long-term cleanup using the Superfund process and federal cleanup dollars. Being added to the list also means public participation in cleanup decisions is assured.

Such designation was sought by dozens of residents and groups, but it was strongly objected to by US Magnesium and Tooele County, which argued a forced cleanup would possibly result in shutting down the plant, leaving hundreds without jobs.

DEQ project manager Chad Gilgen said the Superfund designation will allow remediation plans to be put in place that are "protective of human health and the environment."

Despite concern it might cause the plant to "shut down," Gilgen said it is possible for a Superfund designation to coexist with an operating plant.

"I think that can definitely happen. We are not there to put US Magnesium out of business — we are just there to address the contamination."

The designation becomes "official" with publication in the Federal Register on Wednesday.

e-mail: amyjoi@desnews.com