Gross Reservoir Expansion Project

It takes a long time to build a dam 471 feet high. A lot of other preparatory work is required such as quarrying and preparing the existing dam and foundation for the new dam.

The first planned work supporting the project consists of geotechnical drilling (summer 2018) and exploratory work in the Osprey Point Quarry starting after the reservoir is closed to boating for the season in October 2018. Next up, starting as early as 2019, is site development work and road improvements to the roads accessing Gross Dam. Principally, Denver Water is evaluating improvements and/or traffic control options for the intersection at SH72 and Gross Dam Road, and to Gross Dam Road itself.

Denver Water is committed to working closely with residents to ensure safety and open communication throughout construction.

Gross Reservoir Expansion Project Update Reports

Denver Water is committed to keeping the community informed about the status of the Gross Reservoir Expansion Project. On a bimonthly schedule, Denver Water will publish a project update report that will provide interested stakeholder with valuable information regarding various component of the project. We hope the community, stakeholders, and recreationist find the information helpful and informative. If you have additional questions about these report, please email us.

Accomplishments and Milestones

Looking Ahead

August 20, 2025

Federal Energy Regulatory Commission (FERC) License Amendment Approval – 2018 Dam design, quarry and construction – 2019-2025

Federal Energy Regulatory Commission (FERC) License Amendment Final Application

November 1, 2016

Denver Water’s hydropower unit is regulated by a license granted by FERC; amending the current license is required before the project can begin construction.

U.S. Forest Service (USFS) Agreements

September 1, 2016

New agreements between Denver Water and the USFS to address past, current, and future impacts Denver Water operations have on USFS resources. These agreements identify funding and projects to protect and preserve USFS resources.

Governer Hickenlooper Endorsement

July 1, 2016

“The state’s responsibility is to ensure we do the right thing for Colorado’s future, and this project is vital infrastructure for our economy and the environment”. – Governor John Hickenlooper

Colorado Department of Public Health and Environment 401 Water Quality Certification

June 1, 2016

Colorado Department of Public Health and Environment 401 Water Quality Certification This approval certifies that the project, with the approved mitigation and enhancement measures, will create a net environmental benefit on both the West and East Slopes.

Endangered Species Act, Section 7 Compliance

June 1, 2016

U.S. Fish & Wildlife issued its’ Biological Opinion to implement measures to protect and preserve threatened and endangered species – including the Green Lineage Cutthroat Trout.

Record of Decision and Section 404 Permit from U.S. Army Corps of Engineers

April 1, 2015

After more than 13 years of careful study, evaluation and deliberation, the Army Corps of Engineers approved Denver Water’s request to expand Gross Reservoir by issuing its Record of Decision and Section 404 Clean Water Act Permit.

Learning By Doing Initiated

March 1, 2015

Learning by Doing (LBD) is a collaborative group of water stakeholders – including Denver Water, Grand County, environmental groups, and state and federal agencies – that meet regularly to monitor river health and undertake projects that safeguard Grand County’s home waters.

Latest News / Blog

Water projects take patience, stewardship

Water projects take patience, stewardship

Journal Advocate – June 29, 2018 – "As a result of going above and beyond, the Gross Reservoir expansion includes an "environmental pool" of 5,000 acre feet of water to benefit 17 miles of aquatic habitat in South Boulder Creek..." Read more...

Federal elected officials reiterate support

Federal elected officials reiterate support

We wish to thank members of Colorado's Congressional Delegation for their continued support of the Gross Reservoir Expansion Project! Read their recent letters to Federal Energy Regulatory Commission (FERC) here: Representative Diana DeGette Senators Michael Bennet...