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What happens upstream if Gross Dam expansion remains unfinished?

A river dam under construction is seen from an aerial view of the site.
Alyte Katilius
/
The Colorado Sun
Construction continues with a smaller workforce during a site visit Wednesday, April 9, 2025 at Gross Reservoir in Boulder County. “It’’ll be just under our feet, 131 feet from the crest,” explains Gross Reservoir Expansion Project program manager Jeff Martin of the future height of the dam. “We did limit our workforce availability for the first few days. We’re bringing our workforce back right now under the conditions we're in, and trying to move this forward, because, in the end, the safest way to move forward and the quickest way to move forward for us, is to build the dam.”

As Save the Colorado and Denver Water prepare to face off in a federal courtroom Tuesday, water officials across the state are watching the Gross Dam expansion case closely for its environmental impact and its effect on water projects across the West.

Kirk Klancke, a long-time Grand County environmentalist and president of the Colorado River Headwaters Chapter of Trout Unlimited, said a decision that shuts down the $531 million water project, could also shut down 12 years of work on the Fraser River and its tributaries.

Here’s why: Denver Water owns much of the Fraser with water rights dating back more than 100 years. And it is that water that has historically been piped through the Moffat Tunnel near Rollinsville to fill the existing Gross Reservoir. The new water for the expanded reservoir will come largely from that river as well.

After what’s known as the 2013 Colorado River Cooperative Agreement was signed, Denver Water agreed to conduct extensive restoration work on the river in exchange for being able to raise Gross Dam and bring more water from the Fraser River over to the Front Range.

Klancke said the heavily diverted, scenic waterway would suffer if the deal falls apart. “To dissolve that partnership will be the death of the Fraser River,” he said.

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