Rocky Flats is a former nuclear weapons facility located west of the City of Westminster and Standley Lake, a key drinking water source for Westminster, Thornton and Northglenn.

Cleanup and closure of the site were completed in 2006, and the majority of the site is a national wildlife refuge. Learn more about the Rocky Flats National Wildlife Refuge.

The city encourages those interested to take the time to examine and review this information. Additional information can be found on the Rocky Flats Stewardship Council website.

  • The City of Westminster has been monitoring Standley Lake for radioactivity since 1988, and all sample results have met drinking water standards.
  • Water leaving the Rocky Flats site does not enter Standley Lake. Since 1995, the Woman Creek Reservoir has been in place, just upstream of Standley Lake and downstream of Rocky Flats, diverting water from Rocky Flats around Standley Lake, via Walnut Creek.
  • Extensive sampling for radioactivity in soils, sediment, water and air indicate that the trace amounts of plutonium and americium present in the offsite soils and sediments do not pose a public health risk to those living in or recreating in the area.
  • All conservatively estimated health risks are well below U.S. Environmental Protection Agency significance thresholds, and the offsite areas are suitable for all uses, without restriction.

For greater detail, please refer to the sections below.

This information was prepared by Hydros Consulting of Boulder for the City of Westminster to support concise and accurate responses to questions and comments from the public regarding current health risks related to the Rocky Flats site.

Download the entire report in PDf format.