Gross Reservoir Explained

Gross Reservoir
Location:Boulder County, Colorado
Coords:39.9419°N -105.3728°W
Type:reservoir
Etymology:Named for Denver Water former Chief Engineer Dwight D. Gross.[1]
Outflow:South Boulder Creek
Basin Countries:United States
Agency:Denver Water
Area:440acres
Volume:41811acre.ft
Elevation:2222m (7,290feet)[2]
Pushpin Map:Colorado#USA
Pushpin Map Alt:Location of Gross Reservoir in Colorado, USA.

Gross Reservoir, located in Boulder County, Colorado, is owned and operated by Denver Water. Completed in 1954, the reservoir has a surface area of, and the spillway sits at elevation. The reservoir is undergoing an expansion project.

The reservoir receives water from South Boulder Creek and the western side of the Continental Divide through the Moffat Tunnel. South Boulder Creek flows out of the 340adj=midNaNadj=mid.

Recreation

The reservoir provides opportunities for fishing (including ice fishing), hiking, canoeing, kayaking, and some camping. No water-contact activities such as swimming or wading are allowed. Only non-motorized boats are permitted.[1]

Expansion project

The proposed expansion of Gross Reservoir would allow Denver Water to store an additional of water, drawn mostly from the Fraser and Williams Fork Rivers.[3] Construction on the project, expected to be complete around 2027,[4] will raise the level of the dam by 131abbr=offNaNabbr=off, resulting in an additional 77000acre.ft of water storage capacity in the reservoir and making it the tallest dam in Colorado.[5]

Denver Water applied to the U.S. Army Corps of Engineers for a permit under section 404 of the Clean Water Act, required to construct the expansion, and that permit was granted in 2017.[6] In response, several environmental groups sued USACE on grounds that the agency's deliberations about granting the permit violated the Clean Water Act, Endangered Species Act, and National Environmental Policy Act.[7] In July 2020 the Federal Energy Regulatory Commission granted a required modification to the Federal Power Act license granted to Colorado Water for Gross Dam before it was built.[8]

A contract for design services was awarded to Stantec, an engineering consulting firm, in 2017.

Boulder County announced in spring 2019 that it would require Denver Water to obtain a land use permit under Colorado law before commencing the expansion project.[9] Denver Water submitted its application for that permit in September 2020.[10] Boulder County commissioners approved the expansion in 2021 and accepted a $12.5 million mitigation deal.[11] [12]

Climate

The hottest temperature recorded at Gross Reservoir was 94F on July 9, 2003, June 23, 2012, June 26, 2012, and June 22, 2016, while the coldest temperature recorded was -24F on February 2, 2011.

See also

External links

Notes and References

  1. Denver Water. Gross Reservoir. Viewed 2014-09-22.
  2. 202790. Gross Reservoir. 2014-09-23.
  3. News: Gardner-Smith. Brent. 20 April 2016. Denver Water official says more West Slope water projects 'not on our radar'. Aspen Journalism. 25 November 2020.
  4. News: Ingram . Elizabeth . 2023-07-20 . Why Denver Water is raising Gross Dam . 2023-10-21 . Hydro Review . en-US.
  5. News: Brennan. Charlie. 2 January 2018. Denver firm awarded $13M design contract for expansion of Boulder County's Gross Reservoir. Boulder Daily Camera. Boulder, CO. 25 November 2020.
  6. News: Ingram. Elizabeth. 12 July 2017. Denver Water approved to expand reservoir behind Gross Dam. Hydro Review. 25 November 2020.
  7. News: Brennan. Charlie. 19 December 2018. Environmental groups sue to block expansion of Boulder County's Gross Reservoir. Boulder Daily Camera. 25 November 2020.
  8. News: Jones. Corey H.. 17 July 2020. Boulder County's Gross Reservoir Can Proceed With Expansion Following Lawsuit. CPR News. 25 November 2020.
  9. News: Lacey. Hank. 24 November 2020. Gross Reservoir Expansion Proposal Presents Water Demand, Environmental Concerns. Law Week Colorado. 25 November 2020.
  10. News: Swearingen. Deborah. 5 October 2020. County's review of proposed Gross Reservoir expansion underway. Boulder Daily Camera. 25 November 2020.
  11. News: Booth . Michael . 2023-10-20 . Forest Service says Denver Water is taking down too many trees, rushing requests to change plan to raise Gross Dam . 2023-10-21 . The Colorado Sun . en-US.
  12. Web site: Gross Reservoir Impact Mitigation Fund . 2023-10-21 . Boulder County . en-US.