Rocky Mountain Arsenal National Wildlife Refuge, Nature reserve in Commerce City, United States.

Rocky Mountain Arsenal National Wildlife Refuge is a protected area near Denver in Colorado, covering thousands of hectares with grasslands, wetlands, and open water. Bison graze across the plains, while deer, coyotes, and migratory birds move through the varied habitats.

The Rocky Mountain Arsenal was built in 1942 to manufacture chemical weapons, and after the Vietnam War it was used to dismantle and dispose of them. Congress enacted the refuge act on September 25, 1992, and President George H. W. Bush signed it on October 9, designating the site a national wildlife refuge. Cleanup cost $2.1 billion, and the refuge formally opened on April 2, 2004.

The visitor center features exhibits showing how native wildlife has returned to this landscape and now thrives in restored grasslands and wetlands. Rangers guide groups through the grounds, explaining how different animals interact and how visitors can spot signs of their presence along the trails.

Several walking routes lead through the area and provide access to different landscapes, while a longer driving route allows visitors to cover larger sections. Fishing is permitted at two lakes during certain months, with local regulations posted on site.

The 1986 discovery of a winter bald eagle roost at the arsenal, then an endangered species, helped build the case for protection. The refuge's enabling act was enacted on September 25, 1992, and signed by President George H. W. Bush on October 9. The site formally opened as a refuge on April 2, 2004, after cleanup costing $2.1 billion.