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Sarah Kanouse, Interpretive signage at the Rocky Mountain Arsenal National Wildlife Refuge, 2 May 2014, Flickr


Rocky Mountain Arsenal / Rocky Mountain Arsenal National Wildlife Refuge

In 1942, the U.S. Army established the Rocky Mountain Arsenal (RMA) as an 18,000-acre chemical weapons plant, evicting several hundred farming families. From 1942 to 1982, the Army manufactured chemical weapons and, for much of this period, leased portions of the facility to what is now Shell Oil to make commercial pesticides and herbicides. During four decades of activity, RMA produced an array of military and industrial chemicals, including plant pathogens, incendiaries, and sarin nerve gas. Toxic by-products of many of these compounds were stored in open-air, unlined basins, which led to severe soil and groundwater contamination across portions of the RMA and neighboring communities.

After chemical operations ceased in 1982, wildlife biologists discovered roosting bald eagles at RMA, sparking interest in turning the site into a national wildlife refuge. The designation would facilitate conservation of resident wildlife, and also vastly reduce the cleanup standards required for the Army and Shell to remediate and vacate the site. Congress passed the Rocky Mountain Arsenal National Wildlife Refuge Act in 1992. After the state of Colorado sued over surface and groundwater contamination, the Army and Shell eventually contributed $2.1 billion toward an effort to consolidate and contain contaminants at the RMA; virtually all buildings and infrastructure were also removed.

Today, the Army retains ownership of approximately 1,000 acres near the center of the property—the location of two hazardous waste landfills. The remaining lands have been transferred to other ownership, primarily to the U.S. Fish and Wildlife Service (FWS). The agency now manages 15,000 acres of the RMA as one of the nation’s largest urban wildlife refuges. The FWS continues to restore short- and mixed-grass prairie ecosystems and has introduced bison and black-footed ferrets as part of this effort. In 2011, the FWS built a new visitor center, and officials now estimate annual visitation at 300,000.


Havlick, David. Bombs Away: Militarization, Conservation, and Ecological Restoration. Chicago, IL: University of Chicago Press, 2018.

U.S. Department of Interior, Fish and Wildlife Service. “Draft Comprehensive Conservation Plan and Environmental Impact Statement: Rocky Mountain Arsenal National Wildlife Refuge.” May 2015. Accessed July 28, 2020.

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