Enviro Groups File To Stop Denver Water’s Gross Reservoir Expansion

Grace Hood/CPR News
Denver Water wants to raise the dam at Gross Reservoir 131 feet to increase the storage capacity for more water in wet years.
Photo: Gross Reservoir 3 | Dam View - GHood
Denver Water wants to raise the dam at Gross Reservoir 131 feet to increase the storage capacity for more water in wet years.

Published 9:42 a.m. | Updated 2:46 p.m.

A suit filed against three U.S. government agencies seeks to stop the expansion of Denver Water’s Gross Reservoir in Boulder County.

“At the exact moment in history when flows in the Colorado River need to be protected, Denver Water’s reckless irresponsible project is trying to further drain the river," Gary Wockner, director of Save The Colorado said in a press release.

Gross Reservoir provides water to 1.4 million Front Range customers. The expansion would divert more water from Colorado River headwater tributaries during wet years. In a nutshell, the project seeks to raise the height of the existing dam by 131 feet; storage capacity would increase by 77,000 acre feet.

The environmental groups who sued say the U.S. government permitting process inadequately evaluated the impact of the large project on streamflows. There are also concerns about how construction would affect wildlife.

"We went above and beyond mitigation of environmental impacts under the permits,” Denver Water CEO Jim Lochhead said. “We sat down with Grand County, Eagle County… and a host of agencies across Western Colorado, and developed a series of environmental enhancements to the streams of Western Colorado."

Trout Unlimited is one such group that has supported the Gross Reservoir expansion, citing successful stream augmentation programs along the Fraser River.

CPR News reached out to the U.S. Army Corps of Engineers, which could not comment on the lawsuit.

Revving up the legal gears could pose a setback for Denver Water, which has spent years securing the necessary permits. Now that it has those in place, environmental groups are seeking to stop construction.

Shortages along the Colorado River have been under intense scrutiny lately as Western states pursue critical agreements to manage shortages. Upper basin states including Colorado have agreed on a plan. Now all eyes are on lower basin states, particularly Arizona, to agree on how to manage future shortages along the heavily tapped river.

While it was not named in the lawsuit, Denver Water says it will file legal paperwork so it can intervene and become part of the lawsuit. That’s expected in the coming days.