Eagle Park Reservoir Enlargement Environmental Permitting

Eagle Park Reservoir is an off-channel reservoir located on property formerly owned by the Climax Molybdenum Company (Climax) at the Climax Mine in the upper Eagle River Basin, which was originally used to store mine tailings.  As part of the mine reclamation process, Climax removed tailings deposits from the reservoir and converted the facility to a fresh water storage reservoir.  In 1998, Eagle Park Reservoir Company (EPRC) purchased the reservoir from Climax and began using it for municipal, industrial, irrigation, and environmental water supply purposes.  In 2007, LRE Senior Project Manager Robert Weaver was retained by EPRC to prepare permit applications for a project to enlarge the reservoir by 155 acre-feet to 3,303 acre-feet.  The permitting work for the reservoir enlargement included preparation of an Army Corp of Engineers (ACOE), 404 Permit, NEPA compliance documentation, Endangered Species Act Section 7 consultation, CDPHE 401 Water Quality Certification, and an Eagle County 1041 Permit.

The permitting process for the ACOE 404 Permit was complex because the original dam was constructed prior to the Clean Water Act and the reservoir was reclaimed and developed under the Climax permits for mine reclamation and did not require a 404 Permit.  NEPA compliance requirements therefore needed to include the analysis of the cumulative impacts of the original reservoir and required hydrologic modeling to address impacts on streamflows and water quality.  A water quality assessment was needed for State 401 Certification.  Wetlands delineation was required to quantify impacts associated with inundation of wetland areas along the shoreline of the reservoir, and a wetlands mitigation plan was required to create new wetlands.  Section 7 consultation was required to address impacts to four endangered fish species in the Colorado River caused by water depletions.  In addition, a 1041 Permit Application was prepared and submitted to Eagle County, which was approved with conditions requiring reporting to confirm successful implementation of the wetlands mitigation plan.  The Eagle Park Reservoir Enlargement and mitigation site construction were completed in 2009.  Ongoing work has included oversight of wetlands inspections and reporting.