At a Glance

The 5,237-acrerefuge sits on a plateau oftallgrass prairie and is home tohome to 239 wildlife species.The refuge surrounds a plant that manufacturedplutonium triggers for nuclear bombs for nearly four decades.An energy company applied to drill for oil and gas near the new refuge, further angering environmental groups.

Health concerns surround a newColorado wildlife refuge outside of Denver at the site of a former nuclear weapons plant.

The U.S. Fish and Wildlife Serviceopened the gates on Sept. 15 near a former which used to house aplant that manufacturedplutonium triggers for nuclear bombs for nearly four decades, the Associated Press reports.

The 5,237-acrerefuge sits on a plateau oftallgrass prairie and is home tohome to 239 wildlife species, including bears, elk, cougars, falcons, songbirds and monarch butterflies, among others.

Stephen Parlato wears a gas mask next to his sign warning about the dangers of plutonium at Rocky Flats National Wildlife Refuge outside Denver on Saturday, Sept. 15, 2018, the first day the refuge was open to the public. The refuge is on the outskirts of a former U.S. government factory that manufactured plutonium triggers for nuclear weapons.

(AP Photo/Dan Elliott)

The refuge offers10.2 miles of trails surrounding the plant that has a history of fires, leaks and spills. The 1,300 acres closest to the manufacturing plant remainclosed to the public and state officials discourage visitorsfrom venturing off designated trails.

A lawsuit brought by a coalition of community and national environmental groupstrying to is pending before U.S. District Judge Philip Brimmer, Reuters reports.

Sixty-two pounds of plutonium was discovered stuck in the exhaust ducts of the plant, prompting an$18.5 million fine in 1992. The plant ispermanently closed to the public, but an 8-square-mile buffer zone surrounding the plantwas turned over to the U.S. Fish and Wildlife Service to be used as a refuge.

The lawsuit demands that the site closeuntil more testing can be completed. Brimmer ruled the refuge could be open while the case is heard in court.

The environmentalists argue thata $7.7 billion cleanup overseen by the Environmental Protection Agency was flawed. They say a new environmental study should be conducted.

“Our case will clearly demonstrate that the government does not have an up-to-date assessment of risks to the environment and human health from allowing unlimited public visits to the refuge,” Randall Weiner, an attorney for the coalition, told Reuters.

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Weiner noted that human activity "may stir up remnant plutonium,which if ingested by refuge visitors or residents downwind can cause cancer."

Government agencies, including the EPA andthe Colorado Department of Public Health and Environment say the refuge is safe, the AP reports.

The opening was met with some protest, including Stephen Parlato, who stood at a trailhead wearing a gas mask when the refuge opened.

“You have a situation where you still have plutonium in the soil being disturbed by the wildlife and the weather,” said Parlato. "You even have school districts that have gone on the record to say they do not allow their students to come on trips here. This is an ongoing danger."

Recently, an U.K. based energy company applied todrill, the Denver Post reports.