Recent developments such as higher plutonium levels found at Rocky Flats prove the former nuclear weapons plant is still not safe for the public, a coalition of environmental groups contend in newly filed court documents.

In supplemental filings to an existing federal lawsuit, the organizations cited soil samples taken this month along the eastern edge of the wildlife refuge that came back with plutonium levels more than five times higher than cleanup standards. Attorneys also argued that multiple plans to relocate prairie dogs to the site violates the cleanup plan as burrowing animals could bring dangerous materials to the surface.

“Two recent developments support Plaintiff’s position that the U.S. Fish and Wildlife Service (USFWS) must prepare a fresh Environmental Assessment to analyze its decision to reconfigure hiking, biking and equestrian trails on the Rocky Flats National Wildlife Refuge and allow large numbers of visitors,” Randall Weiner, an attorney representing the groups, said in a news release.

The new documents were added to the case brought last year by the environmental groups which alleged that the government failed to adhere to the National Environmental Policy Act when it opened Rocky Flats. There has not yet been a ruling.

Despite the soil sample findings, toxicologists with the Colorado Department of Public Health and Environment said last month they “do not believe there is an immediate public health threat.” Officials said further sampling and analysis is needed to determine whether it was an isolated instance or a sign of further contamination.

The allegations of safety risks come after more Rocky Flats drama this summer, when the U.S. Department of Justice admitted that it couldn’t find more than 60 boxes of business records tied to the decades-old investigation of the former nuclear facility.

The site opened to the public as a national wildlife refuge in September after years of cleanup concluded in 2005. Environmental groups have long contended that the site has not been adequately cleaned of all possible contaminants.