Cotter Corporation NSL Cañon City, Colorado

CANON CITY — The Cotter Uranium Mill, located two miles south of Canon City, operated continuously from 1958 until 1979, making "yellow cake" for the nuclear power industry from processing uranium ore.

In the last 30 years its operations were intermittent.

In late 2005, Cotter ceased normal operations and stabilized the facility to go into a "stand down" condition. Cotter Corp. executives said the company sought to evaluate operational changes to the mill and assess the feasibility and costs for restart of a re-engineered mill.

Mill operations have released radioactive materials and metals into the environment. These releases contaminated soil and groundwater around the mill and the Lincoln Park area, according to the Colorado Department of Public Health.

The Cotter/Lincoln Park Site was added to the U.S. Environmental Protection Agency’s National Priorities List in 1984, making it a Superfund site. Cleanup activities to date have focused on eliminating the mill site as a source of contamination to Lincoln Park, and eliminating exposures to Lincoln Park residents.

Cleanup activities since 1988 have caused the contaminated groundwater plume in Lincoln Park to shrink in size. However, in 2008, Cotter Corp. received a notice of violation from the state health department indicating a contaminated plume of groundwater exists underneath the uranium mill's neighbor — the Shadow Hills Golf Course, because new groundwater analytical results provide a better definition of the plume of radioactive material north and west of the mill.

A renewed license was issued in December 2004 that continued operation of the uranium mill but disallowed acceptance of radioactive wastes for disposal in the impoundment.

— Tracy Harmon