Federal officials decided against releasing cool water this year from one of the Colorado River’s main reservoirs, a move that would have aided a threatened fish but increased stress on hydropower generation. In a statement accessed by The Associated Press, the Bureau of Reclamation cited significant concerns about hydropower generation and the already strained system when choosing not to release water from the Glen Canyon Dam in Arizona.
The shrinking of the Colorado River and its reservoirs, caused by excessive use and climate change, forced officials to choose between conserving the humpback chub – a fish native to the river – and managing electricity costs for consumers. This decision followed the lowest recorded snowpack in the Colorado River Basin, a crucial water source for farmers, industries, wildlife, hydropower, and over 40 million people across seven U.S. states, tribal nations, and Mexico.
Just a week earlier, federal officials proposed a plan to avoid a major water crisis. The proposal emerged after California, Colorado, Arizona, Nevada, New Mexico, Wyoming, and Utah failed to agree on water distribution strategies. It suggests water cuts shared among California, Nevada, and Arizona. A “cool mix flow” involves releasing cold water from deep within a reservoir, in this case from Lake Powell, to cool the river. Without hydropower turbines in these deep sections, releasing such waters would significantly decrease power generation.
Lake Powell currently holds only 23% of its capacity, reflecting years of overuse and water evaporation as temperatures rise due to climate change. Warm surface water that passes through generators and continues downstream also carries smallmouth bass, a species introduced to Lake Powell in the 1980s. These bass can spawn in warm water, posing risks to the chub and other protected fish further south. Officials confirmed that the 2024 and 2025 cool water releases successfully inhibited smallmouth bass spawning.
Presently, river temperatures downstream of the dam measure approximately 69 degrees Fahrenheit (20.5 degrees Celsius). The Bureau of Reclamation considers recommending cold water releases when average temperatures exceed 60 F (15.5 C) for three consecutive days, a state observed for over a month. Wayne G. Pullan, regional director of the Upper Colorado Basin at the Bureau, highlighted ongoing efforts focusing on rapid response removal, backwater modifications, innovative evaluations, and structural solutions.
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.
Matt Rice of American Rivers, a conservation group, acknowledged the decision as anticipated but disappointing. He emphasized the success of cool mix flows in controlling smallmouth bass in the Grand Canyon and expressed concern for the humpback chub’s survival. Rice also mentioned that elevated temperatures pose threats to the nearby rainbow trout fishery, advocating for collaborative approaches balancing environmental protection and sustainable river management for local power needs.
Utilities purchasing hydropower from Glen Canyon Dam warned that releasing the water could lead to significant costs. It would necessitate finding alternative energy sources, which tend to be more expensive and less renewable, potentially increasing customer electricity bills. Andy Colosimo, from the Colorado River Energy Distributors Association, expressed satisfaction with the decision, appreciating the thoughtful approach taken by the Bureau amid current river challenges.
We’re very pleased with the decision and appreciate Reclamation’s deliberate and thoughtful approach to this, just recognizing the challenges that we’re facing on the river.
The Walton Family Foundation supports the Associated Press in covering water and environmental policies, although AP alone retains control over its content.