CLL Background Information


Cotter/Lincoln Park site summary


  • The site is located adjacent to Lincoln Park , a semi-rural community located two miles south of Cañon City. 
  • The former mill site and part of Lincoln Park are within the Chandler Syncline, a geologic “bowl” underlain with impermeable shale. The Vermejo Formation is a ridge of rock that surrounds most of the Cotter site; however, Sand Creek penetrates the formation and flows through the site from south to north into the Lincoln Park neighborhood to the Arkansas River.
  • The Superfund site includes a portion of the 2,600-acre Cotter mill site and areas where contamination occurred, including surface soils and groundwater in Lincoln Park.


  • The Cotter Corp., an affiliate of General Atomics since 2000, began operating the Cañon City mill in 1958, producing uranium oxide (yellowcake), as well as vanadium and molybdenum as by-products. Originally licensed by the U.S. Atomic Energy Commission, mill licensing authority was transferred to the Colorado Department of Health (now the Colorado Department of Public Health and Environment) when Colorado became an Agreement State in 1968.
  • An alkaline leach mill operated from 1958 to 1978. Liquid wastes containing radionuclides and heavy metals were discharged into 11 impoundments, now known as the Old Ponds Area. All but three of those impoundments were unlined.
  • In June 1965 a flood caused the Old Ponds Area impoundments to overflow into Sand Creek.
  • In 1972, a flood control dam was completed by the Soil Conservation Service on Sand Creek, approximately eight-tenths of a mile north and downstream of the mill area. Since then, surface runoff and spring flow upgradient of the dam have been impounded at the dam. Since 1979, this impounded water has been pumped back to the primary impoundment, where it is evaporated.
  • In 1980 two lined impoundments replaced the ponds in the Old Ponds Area
  • In 1984, the Lincoln Park site was added to the National Priorities list of Superfund sites.
  • In 1988, the state of Colorado and Cotter settled a natural resource damages lawsuit, establishing site characterization and cleanup requirements in the Consent Decree-Remedial Action Plan (CD-RAP).
  • Major activities performed under the CD-RAP include:
  • Connecting Lincoln Park residents to city water;
  • Constructing a groundwater barrier at the SCS dam;
  • Moving tailings remaining from 1981-1983 cleanup activities into a lined impoundment;
  • Excavating contaminated sediments in Sand Creek; and
  • Cotter voluntarily cleaning up several railroad loading areas around Cañon City where uranium ore and other materials had been spilled. 
  • In 2000, a reactive barrier treatment wall was installed below the Sand Creek dam to treat contaminated groundwater flowing under the dam.
  • In January 2002, EPA issued a Record of Decision (ROD) that stated all work necessary to remediate contaminated soils in Lincoln Park had been accomplished.
  • In 2006, ore processing ceased and the mill entered “stand-down” mode, followed by a decision in 2011 to close the mill.
  • In 2012, the state of Colorado began a pause in remediation activities to work toward re-forming the Community Advisory Group (CAG). The new CAG met for the first time in early 2013, and the pause was lifted a few months later.
  • Between 2012 and 2015, the pumpback system pipeline that delivers contaminated water intercepted at the SCS Dam to an evaporation pond experienced a series of releases. Although the contaminated water was contained on Cotter property, Lincoln Park residents expressed concerns about the aging system.
  • On Dec. 9, 2014, the Administrative Settlement and Order on Consent for Remedial Investigation/Feasibility Study (AOC) took effect. This document sets our Cotter’s legal obligation to conduct a remedial investigation/feasibility study (RIFS) in accordance with CERCLA, commonly known as Superfund. Two other documents adopted about the same time, the Radioactive Materials License Amendment 54 and the Agreement Regarding Licensing and Remedial Requirements, work with the AOC to govern the Remedial Investigation and Feasibility Study phase of the cleanup. The 1988 CD-RAP is still in effect, but is no longer the main document guiding cleanup.
  • In August 2015, EPA held a meeting with local stakeholders to identify potential future use options.
  • In December 2016, the department approved Cotter’s proposal to replace the pumpback system pipeline. The new pipeline was completed in the early fall of 2017. In addition, Cotter replaced silt fences that intercepted contaminated sediment with a rip-rap check dam.
  • In July 2017, Cotter Corp. notified the Colorado Department of Public Health and Environment that it would seek the transfer of the radioactive materials license for the former mill to Colorado Legacy Land, LLC, and in September 2017, submitted a license amendment to transfer the license. The department approved the transfer in November 2017. The transfer became final in March 2018 and Colorado Legacy Land has assumed responsibility for all license requirements, including financial assurance and the Consent Decree-Remedial Action Plan, as well as the requirements of the Administrative Settlement Agreement and Order on Consent for Remedial Investigation/Feasibility Study. 
  •  In September 2022, the draft Remedial Investigation (RI) was completed.
  • In February 2023, Colorado Legacy Land (CLL) declared itself insolvent and made it known that as a result it would be unable to continue maintaining, monitoring or guarding the site.
  •  Following CLL's withdrawal, Cotter Corp. was reintegrated in the clean-up process and began working with EPA and CDPHE to develop and implement the next stages of the clean-up.
  • Detailed site timeline.

Environmental Concerns

Contamination includes:

  • Molybdenum.
  • Uranium.
  • Uranium daughter products.
  • Trichloroethylene (TCE), an industrial solvent.