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. This additional work and expected work shutdowns during the winter months could take as much as three additional years, with a total construction schedule totaling over four years. The project schedule for the dam construction scope is dependent on regulatory authorizations, but could start as early as 2019.

The first planned work supporting the project consists of 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. These projects could occur as early as 2019.

It will take three years to mine the on-site quarry, one year prior to the start of construction and two years during construction. Quarry activities will include drilling, blasting, excavation and processing. Quarry work will typically be done during daylight hours. Truck traffic has been drastically reduced with the decision to quarry sand and gravel on-site.

Quarrying materials on-site has reduced that number to around 35 hauling trucks per day carrying cement and fly ash and around 100 construction and personal vehicles per day. Denver Water intends to design the quarry in a way that will reduce long-term viewshed impacts.

Denver Water recognizes the existing intersection at Highway 72 and Gross Dam Road  is unsafe for the expected traffic during construction. These improvements are permanent and will remain in place long after construction is complete. The volume of construction traffic would vary day-to-day and month-to-month depending on the time of year and the type of construction activities. Denver Water is committed to listening to community concerns about potential impacts and have investigated and made a number of changes to the project design including:

  • Reducing truck traffic on Hwy 72 and Gross Dam Road by 75 percent by quarrying sand and gravel at the reservoir site.
  • Developing traffic plans to improve the safety of the intersection at Gross Dam Road and Hwy 72 for the expected truck traffic.
  • Evaluating opportunities for alternative hauling schedules during dam construction.

Denver Water conducted studies on activities that will affect local residents in and around Coal Creek Canyon during construction. While some work, such as actual concrete dam construction, will require 24-hour construction. Denver Water will continue to seek community input from the affected communities throughout construction on such topics as traffic control plans, hauling traffic schedules, viewshed reclamation, tree removal and more. Denver Water is committed to working closely with residents to ensure safety and open communication throughout construction.

Latest News / Blog

Request for Statement of Qualifications for Board of Consultants

Denver Water, owner of Gross Dam and Reservoir in Boulder County, Colorado, is soliciting information from independent consultants regarding their capabilities to evaluate the design and construction of the Gross Reservoir Expansion (GRE) Project. This is an...

Gross Reservoir Mitigation Expected to Help Colorado Trout Fisheries

The Fishing Wire – August 1, 2017 – "Rather than remaining an adversary, Denver Water has joined us and our west slope partners as a partner working to improve conditions in the Fraser watershed," explained Colorado Trout Unlimited Executive Director David Nickum....

Notable Media Coverage – Recent Federal Approval

Gross Reservoir expansion gets approval - Sky-Hi News - July 11, 2017 - "Lochhead said. 'We will complete this project responsibly, as evidence by our actions during the public process and the resulting robust environmental protections we've agreed to along the way.'"...