Gross Reservoir expansion receives final federal approval

Controversial Denver Water project in Boulder County has been in the works for over a decade

By: - July 17, 2020 12:57 pm

An aerial photo of the Gross Reservoir Dam, located in Boulder County. (Photo courtesy of Mitch Tobin, The Water Desk)

Denver Water — which provides water to around a quarter of Colorado’s population — received final approval Friday from the Federal Energy Regulatory Commission to move forward with the expansion of Gross Reservoir in Boulder County.

The expansion of the reservoir will raise the facility’s dam 131 feet and will increase the capacity of the reservoir by 77,000 acre-feet. Of the increased storage capacity, 5,000 acre-feet will be directed to the South Boulder Creek, which is managed by the cities of Boulder and Lafayette. 

“The project provides the system balance, additional storage and resiliency needed for our existing customers as well as a growing population,” said Jim Lochhead, the CEO of Denver Water, in a statement. “We are seeing extreme climate variability and that means we need more options to safeguard a reliable water supply for 1.4 million people in Denver Water’s service area.”

The water utility has been working through the permitting process for nearly 17 years, according to a press release. The estimated cost of the project is projected at $464 million. The design phase is planned to be completed by mid-2021, followed by four years of construction. The project is still caught up in two pending lawsuits.

Gross Reservoir is filled by diverted water from the Fraser River, a tributary of the Colorado River, which is piped underground through the Continental Divide to the highly populated Front Range. For decades, the highly diverted river has experienced low flows, rising stream temperatures, lower fish populations and sediment issues. 

The expansion project has seen continuous pushback from a handful of environmental groups and residents who live around the reservoir and who have expressed concerns about the effect the project will have on surrounding wildlife and traffic, and the disruption it could cause to nearby residents. 

Denver Water is currently appealing a state court decision from December 2019. The ruling requires the utility to go through Boulder County’s land use review process in order to move forward with the expansion project. The case is pending.

Editor’s note: This is a developing story. Check back for updates.

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Moe Clark
Moe Clark

Moe Clark is a freelance journalist and former Colorado Newsline reporter who covered criminal justice, housing, homelessness and other social issues.