Federal officials announced they will not release cool water from Glen Canyon Dam to protect the downstream humpback chub, a threatened native fish in the Colorado River. This decision aimed to alleviate stress on hydropower production amid already challenging conditions.
The Bureau of Reclamation, in an email obtained by The Associated Press, cited significant concerns over hydropower generation under this strained system. The backdrop to this decision is a drastically reduced Colorado River, shrinking from overuse and climate change impacts. Officials had to balance the conservation efforts of the humpback chub with electricity ratepayer costs.
Following the worst snowpack on record for the Colorado River Basin, which supports more than 40 million people across seven U.S. states, tribal nations, and Mexico, federal officials recently proposed measures to prevent a crisis. This came after the states dependent on the river, including California, Colorado, and others, struggled to agree on long-term resource sharing. The proposal suggested water cuts among California, Nevada, and Arizona.
The process known as a “cool mix flow” involves releasing cold water from the lower part of Lake Powell to cool the downstream river. However, releasing this cold water bypasses hydropower turbines, leading to significant power generation loss. The reservoir is now about 23% full, with overuse and evaporation accelerating as temperatures rise.
Warm surface waters draw Smallmouth bass, initially introduced for sport fishing, through generators and downstream, where they spawn if temperatures remain high. Previously, cold water releases in 2024 and 2025 prevented their spawning, protecting species like the humpback chub.
The Bureau monitors river temperatures, recommending cold releases if temperatures exceed 60°F (15.5°C) for three consecutive days. Recent temperatures have surpassed that threshold for over a month.
“Our efforts this year will continue to focus on expanded rapid response removal actions, additional backwater modifications, evaluation of innovative tools, and advancement of durable structural solutions,” noted Wayne G. Pullan, the agency’s regional director of the Upper Colorado Basin.
Matt Rice of American Rivers called the decision disappointing but unsurprising, recognizing cool mix flows as effective against Smallmouth bass in the Grand Canyon. He expressed hope for future solutions balancing environmental protection with meeting the river’s power needs.
Customers buying hydropower from Glen Canyon Dam saw the potential releases as forcing them to adopt costly, less renewable alternative energy options, impacting electricity bills negatively. Andy Colosimo from the Colorado River Energy Distributors Association, representing 155 customers, supported the decision given the current river challenges.
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