The refuge is home to various animals, including a herd of 150 elk, occasional black bear, mountain lions, and moose; as well as badgers, bats, coyote, two species of owl, mule deer, northern flicker, white pelican, black-tailed prairie dog, and porcupine.

[3] This 6,500-acre Rocky Flats Site was one of 13 nuclear weapons production facilities in the United States during the Cold War and was managed by the U.S. Department of Energy (DOE).

The plant operated from 1952 to 1994 with manufacturing activities taking place in the center portion of the site with a large buffer zone around the area.

With oversight from the EPA and Colorado Department of Public Health and the Environment (CDPHE), the DOE completed the $7 billion cleanup in 2005.

The DOE still maintains 1,300 acres as part of their legacy management for long-term care and maintenance, and to ensure the cleanup is functioning as designed.

[7] The Superfund investigation and cleanup effort found that Refuge lands (then-called the Peripheral Operable Unit) would be suitable for unlimited use and unrestricted exposure - that is, any use.

1379, enacted December 28, 2001), most of the 6,240-acre (25.3 km2) Rocky Flats site became a refuge, provided that certification from the EPA is obtained and which asserts that the cleanup and closure have been completed.

[7][8][9] Federal lawsuits have been filed against the United States Fish and Wildlife Service and others in an attempt to block opening of the park.

The Court explained the activist groups "merely rehashed old arguments," and did not provide new evidence or legal authority as support for the lawsuit.

In 2018, several Colorado school districts voted to ban students from attending school-sanctioned trips to the former Rocky Flats plant, citing concerns about the area's previous designation as a Superfund site.

[17] In mid-November, after the elections, Democratic majority leaders of both the State House and Senate (both representing nearby Boulder) joined the renewed call to close the refuge to the public.