Releasing cool water protects fish in the Grand Canyon. That comes at cost to hydropower

As the Colorado River and its once massive reservoirs shrink from overuse and climate change, officials are faced with a decision that pits conservation against ratepayer costs for electricity.

To fight off predators of the humpback chub, a threatened fish native to the river, Glen Canyon Dam in northern Arizona would need to do what is known as a “cool mix flow,” where cold water is released from deep in its reservoir to cool the river below. But there are no hydropower turbines in the cool, deep section, so significant power generation would be lost.

The proposal comes after the worst snowpack on record for the Colorado River Basin, relied upon by farmers, industries, wildlife and more than 40 million people in seven U.S. states, tribal nations and Mexico. It also comes as those states fail to reach a long-term agreement on how to share the river's dwindling resources beyond this year, when the guidelines expire.

“There is a limited water supply. It’s getting even lower. And with that, a lot of hard decisions need to be made,” said John Berggren, regional policy manager for the environmental nonprofit Western Resource Advocates.

Utilities that buy this hydropower say the cool water releases would be costly because they would have to spend millions to buy alternative energy and would increase financial hardship for customers. But supporters say that without cool releases, the warm waters projected downstream this summer would allow non-native predatory fish to spawn, further threatening the humpback chub, and would destroy a world-famous trout fishery nearby.

The Bureau of Reclamation, which is expected to announce a decision in the next couple of weeks, said in a statement that it is weighing several factors including the ecological health of the river and the hydropower production of the dam. The Interior Department, which oversees the bureau, declined to comment. If the cool water release is approved, it would likely happen from June to October through jet tubes, bypassing the turbines near the warmer surface.

Lake Powell, one of two massive reservoirs on the Colorado River, is just 23% full after decades of overuse and evaporation of water as average temperatures rise because of climate change. A record low inflow is expected this summer. With such a low reservoir, warm water near the surface gets sucked through the generators and sent downstream.

Smallmouth bass, introduced in Lake Powell in the 1980s for sport fishing, live at that warm surface, and also get sucked through the hydropower generators and into the river below. That's a problem for the humpback chub and other federally protected fish in the Grand Canyon, a 278-mile (447-kilometer) stretch farther south on the river that's world-famous for its geologic formations. A recent study shows that roughly half the bass survive the generators. If the river below is warm enough, they spawn.

Smallmouth bass already feast on humpback chub in the river’s upper section, where agencies spend millions of dollars annually to keep the intruders in check. Native fish have been safer below Glen Canyon Dam because it blocks the path to the Grand Canyon — but that may not be true for long.

Water temperatures just downstream of the dam are expected to shatter records set in 2022, when smallmouth bass were first found there. Officials project that water will consistently exceed 60 degrees Fahrenheit (15.5 Celsius) by mid-June due to the warm water being pulled in from Lake Powell. Any higher than that, and non-native predatory fish that pass through the dam could reproduce.

Officials say cool water releases from Lake Powell in 2024 and 2025 successfully prevented spawning.

It’s critical to consider the cost of not doing the cool mix, Heather Whitlaw, field supervisor with the U.S. Fish and Wildlife Service, said during a recent meeting on managing the issue. “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.”

With no long-term solution to keep the predators from passing through the dam, withholding cool water would force officials to rely solely on manually removing them downstream.

Utilities reliant on hydropower from federal generators are worried.

If the cool water releases are approved, it could mean bypassing about half the generation at Glen Canyon Dam, forcing utilities to buy power elsewhere that would likely be more expensive, according to the Utah utility group Heber Light & Power.

“We keep hearing comments that we must continue Cool Mix because the cost of not doing it will be even greater,” the Colorado River Energy Distributors Association, which represents about 155 customers who buy federal hydropower generated from the river and opposes the releases, said this month in a letter to Interior Secretary Doug Burgum. “We would like to understand what remediation would consistently cost more than $20 to $30 (million) per year.”

The association said the releases are not a sustainable solution to prevent smallmouth bass from reproducing and threaten a critical fund used to operate, maintain and invest in hydropower and transmission facilities.

During the cool water releases in 2024, nearly 900,000 acre-feet of water bypassed the generators, costing $19 million in replacement energy costs, according to the Bureau of Reclamation. It’s unclear how much water would bypass the generators this year, although the cost to replace it is anticipated to be around $25 million — roughly the total cost to hydropower users from the prior two years.

The ongoing loss of hydropower due to Lake Powell's decline has brought challenges to Heber Light & Power as the population grows, said Emily Brandt, the utility’s energy resource manager. The overall decline has led to rate hikes the past five years.

Ann Moulton, who lives in Heber City, has seen her residential electricity bill from Heber Light & Power steadily rise. Her bill this April was $125.98, up from $103.24 and $86.14 for the same month in the previous two years. That's impacting her budget, she said.

Other customers are struggling to pay. So far this year, the utility has seen a jump in late payments over the past two years, from 10% to 12%.

Brandt said the utility supports caring for fish, “but this particular experiment seems unnecessary.”

“We’re already seeing reduced generation from drought, and now we’re seeing even further reduced generation because of this environmental experiment,” Brandt said.

Dave Foster still remembers the 2022 trout die-off in Glen Canyon, a remote stretch of river between the dam and the start of the Grand Canyon. Warm water killed nearly half the rainbow trout the world-renowned fishery relies on, said Foster, who has been working on or around that stretch of river since age 13.

He and other guides are still recovering from the die-off, he said, as “the population has simply not rebounded.” But cool water releases in recent years have offset more negative impacts, and more this year would get them through the fall and winter.

Foster has warned customers booking trips after mid-June that he might cancel if the water gets too warm, which can stress fish. Without cool water releases this year, “that's it for the trout fishery,” he said. “There's no ambiguity about it. It will destroy it.”

The Associated Press receives support from the Walton Family Foundation for coverage of water and environmental policy. The AP is solely responsible for all content. For all of AP’s environmental coverage, visit https://apnews.com/hub/climate-and-environment

In the third to last paragraph, corrects the name of a stretch of the river to Glen Canyon instead of Marble Canyon.

FILE - A sign reading "keep out" is displayed just upstream of Glen Canyon Dam at Lake Powell, June 8, 2022, in Page, Ariz. (AP Photo/Brittany Peterson, File)

FILE - A boat floats past bathtub rings showing how low Lake Powell levels have dropped June 7, 2022, in Page, Ariz. (AP Photo/Brittany Peterson, File)

FILE - Utah State University lab technician Justin Furby weighs a smallmouth bass June 7, 2022, in Page, Ariz. (AP Photo/Brittany Peterson, File)

FILE - Utah State University master's student Barrett Friesen steers a boat near Glen Canyon dam on Lake Powell on June 7, 2022, in Page, Ariz. (AP Photo/Brittany Peterson, File)

COLUMBIA, S.C. (AP) — The South Carolina Senate on Tuesday rejected President Donald Trump’s push to redraw the state’s congressional district in hopes Republicans could gain an additional seat in the midterm elections.

Senators had political concerns, worrying that any map in a state where Democrats got at least 40% of votes in the past eight presidential elections couldn’t guarantee Republican wins in all seven districts.

And there were logistical worries. Statewide primaries are June 9, with early voting starting Tuesday. The plan had called for throwing out any congressional votes already cast and holding another statewide primary just for U.S. House races in August.

Election officials said holding three statewide elections in five months would require employees to work around the clock to prepare voting machines and ballots and to meet legal requirements.

The proposal passed the South Carolina House last Wednesday after two days of long debate.

Trump’s push in South Carolina was part of his broader effort to get Republican-led states to redraw congressional maps in hopes of retaining the party’s slim majority in the November elections.

THIS IS A BREAKING NEWS UPDATE. AP’s earlier story follows below.

COLUMBIA, S.C. (AP) — Early in-person voting began Tuesday in South Carolina’s primaries, as state senators considered whether to cancel the congressional votes and instead schedule a new primary under revised districts designed to help Republicans oust a longtime Democrat.

Among the first to cast an early ballot in the small city of Orangeburg was U.S. Rep. Jim Clyburn, the Democrat whose district Republicans are trying to reshape in their quest for a clean sweep of South Carolina's seven congressional seats. A defiant Clyburn insisted he would run for reelection, regardless of what the district looks like.

“I’m OK if it’s Trump plus 20,” Clyburn said while describing the potential Republican advantage in a reshaped district. “I would be running where I live.”

The political drama in South Carolina is part of a Republican strategy — propelled President Donald Trump — to redraw voting districts to the GOP's advantage in an attempt to hold on to a slim House majority in the midterm elections. Republicans have been moving quickly to try to leverage a recent U.S. Supreme Court ruling that weakened minority protections under the federal Voting Rights Act.

But the GOP also suffered a setback Tuesday in Alabama, where a three-judge federal panel issued a preliminary injunction blocking the state from using a Republican-drawn congressional map that could help the GOP win an additional seat. The court said the Republican plan “intentionally discriminated based on race” by including only one Black-majority district and ordered the continued use of a court-imposed map that includes two districts with a significant proportion of Black residents.

Alabama Attorney General Steve Marshall, a Republican, vowed a quick appeal to the U.S. Supreme Court and predicted an eventual victory.

Democrats, who have suffered their own share of setbacks in the national redistricting battle, praised the turn of events in Alabama.

The “fight for justice is far from over in states across the country where politicians are enacting gerrymanders on top of gerrymanders to erase equal representation for communities of color,” said Marina Jenkins, executive director of the National Redistricting Foundation, a nonprofit affiliate of the National Democratic Redistricting Committee.

Voting districts typically are redrawn after a census at the start of a decade. But Trump has urged Republican-led states to redistrict ahead of the November elections to try to rebuff political headwinds, which typically result in lost congressional seats for the president’s party in midterms.

Since Trump first urged Texas to redraw its voting districts last summer, Republicans also have enacted new House districts in Missouri, North Carolina, Ohio, Florida and Tennessee. Meanwhile, voters in California adopted new Democratic-drawn districts, and a court imposed a favorable map for Democrats in Utah. Democrats suffered a setback in Virginia, where the state Supreme Court invalidated a voter-approved redistricting plan that could have helped Democrats win additional seats.

Redistricting discussions are ongoing in Louisiana following an April high court ruling that struck down a majority-Black congressional district as an illegal partisan gerrymander. The Louisiana House could vote later this week on a new map that could eliminate a seat held by Democratic U.S. Rep. Cleo Fields and improve Republicans' chances of winning six out of the state's seven seats.

The Congressional Black Caucus on Tuesday called on major corporations across the U.S., including those that previously expressed support for voting rights and racial justice, to oppose redistricting efforts by Republican-led states that seek to eliminate majority-Black U.S. House districts. That comes after the caucus last week called for Black athletes to boycott public universities in states that are gerrymandering congressional maps to eliminate districts held by Black lawmakers.

More than 26,000 votes were cast in South Carolina by noon Tuesday on the first day of early voting for the June 9 primary after Democrats called for people against a proposed new map to turn out in force. In 2022, about 125,000 early votes were cast the entire two weeks.

The Republican-led House already has passed a plan that would reconfigure Clyburn's district, void the results of current congressional primaries and instead hold new U.S. House primaries in August.

Trump has lobbied for the plan, making at least two phone calls to Republican state Senate Majority Leader Shane Massey and also phoning in to a private meeting of Republican senators earlier this month. He also has maintained the pressure on social media.

Debate has stalled in the Senate, where Democrats are staunchly opposed and some GOP lawmakers have concerns that an aggressive redistricting could backfire by making some Republican-held seats susceptible to losses because of the addition of Democratic voters.

Clyburn noted that when state lawmakers last redrew congressional districts, after the 2020 census, they spent months holding meetings across the state to gather public suggestions. Although that map resulted in a 6-1 seat advantage for Republicans over Democrats, the process was orderly and fair, he said.

“When the map was challenged, the U.S. Supreme Court said, yes, this is constitutional,” Clyburn said. But now, “this White House says, to hell with the process, to hell with the Constitution, just do what we want done.”

Chandler reported from Montgomery, Alabama, and Lieb from Jefferson City, Missouri.

Republican South Carolina Sen. Carlisle Kennedy, left, Democratic Sen. Ronnie Sabb, middle, and Republican Sen. Jeff Zell, right, watch a video during a session on redistricting on Tuesday, May 26, 2026, in Columbia, S.C. (AP Photo/Jeffrey Collins)

Rep. Jim Clyburn, D-S.C., center, joined by House Minority Leader Hakeem Jeffries, D-N.Y., left, stands with members of the Congressional Black Caucus during an event outside the Capitol in Washington, Tuesday, May 19, 2026. (AP Photo/J. Scott Applewhite)