Since its establishment in 1942, the Rocky Mountain Arsenal (RMA) has played a unique role in the service of our nation. From Arsenal of Democracy to urban wildlife refuge, the RMA has been critical to achieving U.S. defense, space exploration, environmental remediation and conservation goals. The timeline below highlights important milestones from each decade. To learn more and view artifacts from each period, visit the Refuge Visitor Center.

 1940s.jpgWinning the War


1941 — Japan attacks Pearl Harbor, and the United States enters World War II.

1942 — The U.S. Army establishes the Rocky Mountain Arsenal to produce chemical weapons as a war-time deterrent. The 17,000-acre site is 10 miles northeast of Denver.

1943 — RMA employees work around the clock to manufacture mustard gas, Lewisite, chlorine gas and incendiary weapons. By year end, the United States has outproduced the Axis Powers by 150 percent.

1943 — From 1943 to 1946, the Rose Hill Prisoners of War Camp houses captured German soldiers at the RMA.

1947 — The U.S. Army places the RMA on standby status and leases some facilities to private industry. One of the lessees, Julius Hyman and Company, manufactures agricultural chemicals at the site.

1950s.jpgCold War to Spaceflight


1950 — North Korea invades South Korea, and the U.S. Army reactivates the RMA to produce chemical weapons and incendiary munitions for the Korean War and Vietnam Conflict.

1952 — Shell Chemical Co. purchases Julius Hyman and Company and continues to manufacture agricultural chemicals at the RMA until 1982.

 1960s - 1970s

1962 — Treated liquid waste is injected into a deep well located more than 12,000 feet below the ground surface.

1966 — Following reports of localized earthquake tremors, the U.S. Army concludes the deep well injection program.

1969 — Powered by rocket fuel propellant manufactured at the RMA, Apollo 11 lands on the moon.

1973 — The Vietnam Conflict ends, and demilitarization becomes the primary focus of the RMA.

1980s.jpgEnvironmental Cleanup and Cooperation


Early 1980s — All production at the RMA ceases, and the mission shifts to environmental remediation and restoration.

1984 — The U.S. Army conducts the RMA Remedial Investigation / Feasibility Study, which includes the systematic investigation of contamination and the development and evaluation of cleanup alternatives.

1986 — Workers discover a communal roost of bald eagles at the RMA.

1987 — The EPA places the RMA on the National Priorities (or “Superfund”) List.

1989 — The U.S. Army, EPA and Shell sign the Federal Facilities Agreement, which provides a framework for decision-making and for completing 14 Interim Response Actions (IRAs) while final cleanup plans are developed.

1989 — The U.S. Fish and Wildlife Service establishes a field office at the RMA to manage bald eagles and other wildlife.

First in Safety


1992 — Congress passes the 1992 Rocky Mountain Arsenal National Wildlife Refuge Act, which designates the site as a future national wildlife refuge.

1995-1996 — Following extensive community input, the Off-Post and On-Post Records of Decision (ROD) are signed. The documents provide the framework, purpose and overall rationale for remediation of the site.

1996 — The U.S. Army, Shell and U.S. Fish and Wildlife Service enter into a unique public-private teaming arrangement called the Remediation Venture Office (RVO) to facilitate the safe, timely and cost-effective cleanup and transition of the site.

1999 — The RMA becomes the first environmental cleanup site in the nation to receive the Occupational Safety and Health Administration’s (OSHA) highest workplace safety award.

2000s.jpgRefuge Established


 2003 — The EPA removes 917 acres of RMA land from the National Priorities List. The land is sold to Commerce City for commercial and retail development.

2004 — After the EPA certifies that cleanup actions are complete, the U.S. Department of Defense transfers 5,000 acres of RMA land to the U.S. Department of the Interior to officially establish the Rocky Mountain Arsenal National Wildlife Refuge.

2007 — The EPA honors the RMA with its national Land Revitalization Award. American bison are reintroduced to the site that same year as part of a nationwide conservation effort. 

2010s.jpgSurface Environmental Cleanup Completed


2010 — All surface environmental cleanup work concludes. Following a final land transfer, the Refuge expands to 15,000 acres and becomes one of the largest urban national wildlife refuges in the United States.

2011 — In cooperation with federal, state and local regulatory agencies, the U.S. Army permanently maintains 1,000 acres at the site containing the landfills, waste consolidation areas and groundwater treatment facilities.

2015 — Black-footed ferrets are reintroduced at the Refuge as part of a nationwide recovery program for the endangered species.