Dam Design and Construction

Denver Water, Boulder County strike agreement on Gross Reservoir expansion

Denver Water, Boulder County strike agreement on Gross Reservoir expansion

Denver Water and Boulder County have entered into an agreement related to the Gross Reservoir expansion that marks the final step in a nearly 20-year federal, state and local review to permit the project.

Denver Water will commit nearly $13 million and make significant adjustments to construction practices to address the county’s concerns over impacts to the local community and environment, as well as contributing land to Boulder County’s open space inventory. In exchange, Boulder County agrees that the project may proceed, with construction expected to begin in April 2022.

“We appreciate the County’s effort to work through the issues and come to an agreement that will help ease concerns about the project’s impact on nearby residents, bring benefits to Boulder County residents through enhancements to its trails and open spaces and allow Denver Water to proceed on an undertaking critical to the water security of 1.5 million people in the Denver region,” said Denver Water Chief Executive Officer/Manager Jim Lochhead. “Denver Water and Boulder County have shared values. We both believe deeply in the need to address climate change, conserve our water resources and protect the region’s precious environment. This agreement reflects those values through dedicated funding and actions on the ground.”

The settlement puts to rest a federal lawsuit filed by Denver Water in July, asking the court to resolve a conflict centered around whether Boulder County has any land-use permitting authority over the project given the Federal Energy Regulatory Commission’s order requiring Denver Water to proceed with expansion of the reservoir.

The expansion of Gross Reservoir will offer crucial protection to the utility’s water supplies from the threat of catastrophic wildfire and prolonged drought – the same forces that nearly 20 years ago combined to threaten Denver Water’s ability to ensure drinking water to its customers. Last year’s record wildfire season, which generated the three largest forest fires in Colorado history, only just missed triggering major impacts to Denver Water’s supplies. A 7.6-MW hydropower facility is located near the base of the dam.

The agreement includes numerous components across multiple areas of emphasis. They include: reducing construction and traffic impacts; environmental and recreational enhancements; and commitments to conservation and climate action.

Denver Water has worked for years with local governments and citizen groups on the West Slope to address the impacts of an expanded Gross Reservoir. Those talks resulted in the Colorado River Cooperative Agreement in 2013, a collective effort involving 18 signatories and 40 partner organizations that began a new era of collaboration and conflict resolution between Denver Water and the West Slope to provide environmental benefits and protections for the Colorado River watershed.

The utility also made — and in many cases has already carried out —commitments worth tens of millions of dollars to offset impacts of the reservoir expansion in conditions attached to permits issued by the U.S. Army Corps of Engineers and FERC, as well as through separate agreements with the U.S. Forest Service.

Previous commitments have also included projects of direct benefit to Boulder County: raising the dam by an additional 6 feet to create 5,000 acre-feet of storage space in Gross Reservoir for environmental flows in South Boulder Creek as well as to bolster water supplies for the cities of Boulder and Lafayette, greater production of clean energy from the hydroelectric facility at Gross Reservoir, improvements to portions of South Boulder Creek damaged in the 2013 floods and expanded recreational opportunities at the reservoir.

“In the two decades Denver Water has spent preparing for the project, we have been driven by a singular value: the need to do this expansion the right way, by involving the community, by upholding the highest environmental standards and by protecting and managing the water and landscapes that define Colorado,” Lochhead said. “Boulder County and its residents share these perspectives, and we look forward to continuing to work with them as the project moves ahead.” 

Denver Water is a public agency funded by water rates, new tap fees and the sale of hydropower.