Historic Step Forward to Secure Environmental Flows in the Colorado River

December 11, 2025

On the evening of November 19, a packed conference room in the Denver West Marriott erupted in cheers when the Colorado Water Conservation Board approved one of the largest ever dedications of water for the environment in Colorado’s history. This new deal, if completed, will ensure that water currently running through the aging Shoshone Hydropower Plant on the Colorado River, deep in the heart of Glenwood Canyon, will keep flowing through the canyon when the plant eventually goes off-line. It’s not a sure thing yet – water court wrangling over the details and financial hurdles remain. But the Board’s action was a crucial step forward.  

Currently, when the plant is running full steam, 1,400 cubic feet/ second (think 1,400 basketballs full of water passing by every second) is diverted out of the river into a tunnel and then into massive pipes visible against the canyon walls, where the power of falling water spins turbines to generate electricity. The water is then returned back to the river. Under the new deal, when the plant stops operating (it is over 100 years old and vulnerable to rockfall), the water would instead stay in the river, vastly improving conditions for fish and the bugs they eat in the 2.4-mile reach between the diversion and the powerplant’s return flows. The dedication of the plant’s water rights to that stretch of river would bring benefits that ripple hundreds of miles up and downstream because of the crucial role these water rights play in controlling the river’s flow through Western Colorado.  

Shoshone Power Plant, Colorado | Hannah Holm
Shoshone Power Plant, Colorado | Hannah Holm

In Colorado, as in most of the West, older water rights take priority over newer ones when there’s not enough water to satisfy everyone’s claims.  On the Colorado River, the Shoshone Hydropower rights limit the amount of water that can be taken out of the river upstream by junior rights that divert water from the river’s headwaters through tunnels under the Continental Divide to cities and farms on the eastern side of the Rocky Mountains. The new deal to enable the Shoshone rights to be used for environmental flows would preserve those limitations on transmountain diversions in perpetuity.  

Upstream from the power plant, near the ranching town of Kremmling, Colorado, the river carries less than half the water it would without the existing transmountain diversions. This stresses fish populations and the iconic cottonwood groves that line the river. The Shoshone rights downstream prevent these diversions from being even larger. Because the power plant returns all the water it uses to the river without consuming it, the water continues to provide benefits downstream from the plant to rafters, farms, cities and four species of endangered fish that exist only in the Colorado River Basin. Securing these flows for the future is particularly important as climate change continues to reduce the river’s flow, which has already declined by roughly 20% over the past two decades.  

The people cheering in the hearing room represented cities, towns, counties and irrigation districts from up and down the Colorado River. Their entities had pledged ratepayer and taxpayer dollars to help secure the rights in the complex transaction spearheaded by the Colorado River Water Conservation District. Environmental organizations, including American Rivers, Audubon, Trout Unlimited and Western Resource Advocates, were also parties to the hearing and supportive of the deal, but were vastly outnumbered.  

The Coloradans cheering in that room were there because their constituents’ livelihoods, clean drinking water and quality of life depend on a living Colorado River. American Rivers is proud to stand with them and will continue advocating for the completion of this historic water transaction.  

Clean Water, River Restoration