Army Rocky Mountain Arsenal

What's New?

Known today as an urban national wildlife refuge, the Rocky Mountain Arsenal is one of the most studied environmental cleanup sites in the country.  The U.S. Army permanently manages approximately 1,000 acres at the site to ensure the remedy remains protective of public health and the environment. Explore this site to learn more about the operation and maintenance of the environmental cleanup. To learn more about the national wildlife refuge, visit the refuge online.                                      


 Crews Relocating, Upgrading Portion of Northern Pathway Groundwater Treatment System

Crews are installing a small groundwater treatment building, along with several new groundwater extraction wells, recharge trenches and monitoring wells, in an area north of Rocky Mountain Arsenal. The work is taking place along the railroad tracks west of Highway 2 and north of 104th Avenue in Commerce City.

The changes are being made to relocate groundwater treatment facilities from an expiring lease area to an area with a long-term easement. The new groundwater facilities will replace a portion of an existing treatment system and ensure RMA's groundwater cleanup goals continue to be met.

The project, which is being done in cooperation with the EPA, Colorado Department of Public Health and Environment and Tri-County Health Department, will be completed by September 2021. 

To learn more, view the fact sheet, map and schedule. If you have further questions, please contact the RMA Public Affairs Office at 303.289.0300


 Draft Final Fifth Five-Year Review Report Now Available for Comment 

 The draft final Fifth Five-Year Review Report is now online for comment. The review covered the period from 2015 to 2020. 

The U.S. Army conducted the Five-Year Review in cooperation with the EPA, Colorado Department of Public Health and Environment and Tri-County Health Department. The purpose of the review was to assess the ongoing protectiveness of the cleanup for human health and the environment. A multiagency team also evaluated whether any changes had occurred to environmental standards that affect the site. 

If you would like to submit comments on the draft final Fifth Five-Year Review Report, please email them to: All comments received in writing by July 23 will be considered in the final report as part of RMA's site record. 

You can review the report online here. To learn more about the Five-Year Review (FYR) process, click here.







Rocky Mountain Arsenal

6550 Gateway Road

Commerce City, CO 80022-1748

Public Affairs

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