Gross Reservoir Expansion Project

The Gross Reservoir Expansion Project will undergo approximately three years of design, finishing in 2021, followed by the start of construction in 2022.

Primary dam construction is anticipated to last two construction seasons, a total of 18 months. During this time, work at the construction site will often be 24 hours a day, 7 days a week. The project involves the raising of the existing 340 foot tall Gross Dam by an additional 131 feet to create the new larger reservoir and additional storage. Based on the concept design, once complete, Gross Reservoir will be the tallest dam in Colorado and will contain about 1.5 million cubic yards of concrete, about half the volume of Hoover Dam.

 

Technically Speaking

 

The U.S. Army Corps of Engineers, Omaha District Regulatory Branch, prepared an Environmental Impact Statement beginning in 2003 to analyze environmental effects of enlarging the existing Gross Reservoir (near Boulder, Colorado) to supply 18,000 acre-feet per year new firm yield of water to its Moffat Collection System. On July 6th 2017, the U.S. Army Corps of Engineers approved Denver Water’s request to raise Gross Dam in Boulder County.

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Latest News / Blog

Long-term recreation closure at Gross Reservoir

Boulder, Colo. — June 22, 2022 — Recreation at Gross Reservoir will remain closed for multiple weeks following the June 18 fatal accident at the Gross Reservoir Expansion Project where an engineer with six years of experience lost his life. This is essential as crews...

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Gross Reservoir recreation closed until further notice

Boulder, Colo. — June 18, 2022— Emergency responders are working on an accident that took place overnight at the Gross Reservoir Expansion Project site, in which a construction haul vehicle veered off the road into the reservoir. First responders and other agencies...

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