Highlights
- The Bureau of Reclamation will decide within weeks whether to release cold water from Glen Canyon Dam to block invasive smallmouth bass from spawning in the Grand Canyon.
- Cool-mix releases would bypass about half the dam's hydropower turbines, costing utilities an estimated $25 million in replacement energy this year alone.
- Lake Powell sits at just 23% capacity, and water temperatures downstream are projected to exceed 60 degrees Fahrenheit by mid-June — the threshold at which non-native predatory fish can reproduce.
- Without cool releases, guides and wildlife officials say the Marble Canyon trout fishery faces destruction and humpback chub recovery becomes effectively impossible.
The Bureau of Reclamation is expected to announce within weeks whether Glen Canyon Dam will again release cold water from deep in Lake Powell to protect threatened native fish in the Grand Canyon, a move that would bypass roughly half the dam's hydropower turbines and cost downstream utilities an estimated $25 million in replacement energy costs this year, according to the Associated Press via KTAR, corroborated by ABC News and AZ Central.
The proposal centers on what officials call a "cool mix flow", releasing cold water through jet tubes that bypass the turbines, which draw from warmer surface water. The problem: smallmouth bass, introduced into Lake Powell in the 1980s for sport fishing, live near that warm surface, pass through the generators, and survive into the river below at a rate of roughly 50%, per a recent study. If downstream water temperatures exceed 60 degrees Fahrenheit, the bass can spawn, threatening the humpback chub, a federally protected species native to the Colorado River system.
Lake Powell is at 23% capacity after decades of overuse and rising temperatures, and a record low inflow is expected this summer. Water temperatures just downstream of the dam are projected to shatter records set in 2022, the year smallmouth bass were first detected below the dam, and consistently exceed the 60-degree spawning threshold by mid-June.
The Colorado River Energy Distributors Association, which represents about 155 customers who buy federal hydropower from the river, opposes the releases. In a letter this month to Interior Secretary Doug Burgum, the association questioned whether remediation would consistently cost more than $20 to $30 million per year, framing the cool-mix approach as financially unsustainable and a threat to a critical fund used to operate and maintain hydropower infrastructure. During the 2024 cool-water releases, nearly 900,000 acre-feet of water bypassed the generators, costing $19 million in replacement energy, according to the Bureau of Reclamation.
For Heber Light & Power, a Utah utility that buys federal hydropower, the financial pressure is already visible in customer bills. Energy resource manager Emily Brandt said the utility supports fish conservation but called the releases an unnecessary experiment given that drought has already reduced generation. Residential customer Ann Moulton's April electricity bill from the utility reached $125.98, up from $103.24 the prior April and $86.14 the year before that. Late payments at the utility have climbed from 10% to 12% so far this year.
On the conservation side, U.S. Fish and Wildlife Service field supervisor Heather Whitlaw told a recent management meeting that withholding cool water amounts to abandoning any realistic path to humpback chub recovery. "We are certainly just giving up on the future for any kind of recovery for humpback chub and all of the other pieces of the system that rely on those cooler water temperatures," Whitlaw said.
The stakes extend beyond the native fish. Dave Foster, a guide who has worked Marble Canyon since age 13, said the 2022 warm-water event killed nearly half the rainbow trout in that world-renowned stretch of river and the population has not rebounded. He has already warned customers booking trips after mid-June that cancellations are possible. Without cool releases this year, Foster said, the trout fishery faces complete destruction.
The Interior Department, which oversees the Bureau of Reclamation, declined to comment. If approved, cool releases would run from June through October via jet tubes. The bureau's decision is expected in the next couple of weeks.
Sources
Every factual claim in this article traces to one of the sources below. See how we work for the editorial process.
- ktar.com retrieved 26/05/2026 13:49
- abcnews.com retrieved 26/05/2026 13:49
- AZ Central retrieved 26/05/2026 13:49
Authored by The Scottsdale Signal. Drafted by AI from primary-source material under our beat-specific editorial guides; reviewed by humans before publish under our five-gate process. Sources retrieved at 26/05/2026 13:49. Every claim traces to a source.
