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Record of Decision approves Moffat Collection System Project

Published July 7, 2017
Gross Reservoir dam, Boulder County, Colorado.

Gross Reservoir dam, Boulder County, Colorado.

OMAHA, Neb. – The Corps of Engineers, Omaha District, finalized its Record of Decision approving the Moffat Collection System Project on July 6, 2017. The project is proposed by the Board of Water Commissioners for the City and County of Denver, also known as Denver Water. In order to meet its future water needs, Denver Water, proposes to enlarge their existing 41,811-acre-feet Gross Reservoir by 77,000 acre-feet for a total storage capacity of 118,811 acre-feet. Gross Reservoir dam is located in Boulder County, Colorado, approximately 35 miles northwest of Denver and six miles southwest of the City of Boulder. The enlargement would be accomplished by raising the existing concrete gravity arch dam by 131 feet, from 340 to 471 feet high. The surface area of the reservoir would be expanded from approximately 418 acres to 842 acres. Using existing collection infrastructure, water from the Fraser River, Williams Fork River, and South Boulder Creek would be diverted and delivered during average to wet years via the Moffat Tunnel and South Boulder Creek to Gross Reservoir.  

Denver Water requested a Section 404 Clean Water Act Permit from the Corps’ Omaha District Denver Regulatory Office. Due to the potential for significant environmental impacts to the East and West Slopes of Colorado, this project resulted in the preparation of an Environmental Impact Statement. As the lead federal agency, the Corps published the Final EIS on April 25, 2014. The State issued the Section 401 Water Quality Certification for the Moffat Project on June 23, 2016. This certification was necessary for the Corps determination under Section 404 of the Clean Water Act.  By finalizing the Record of Decision on July 6, the Corps is concluding the National Environmental Policy Act process for the project.

The Record of Decision and all related documents are located on the District website at: http://www.nwo.usace.army.mil/Missions/Regulatory-Program/Colorado/EIS-Moffat/



John Urbanic

Release no. 17-063