Millions of fish died at an Ontario nuclear plant in 2025. Now its operator faces federal charges

Bruce Power, the private company that operates the Bruce Nuclear Generating Station, faces two federal Fisheries Act charges after millions of Lake Huron fish died over a period of two months in 2025.

Fisheries and Oceans Canada said Bruce Power exceeded annual fish kill limit by 200 times

Colin Butler · CBC News

· Posted: Nov 03, 2026 4:00 AM EST | Last Updated: 15 minutes ago

Listen to this article

Estimated 5 minutes

The audio version of this article is generated by AI-based technology. Mispronunciations can occur. We are working with our partners to continually review and improve the results.

The private company that operates the Bruce Nuclear Generating Station faces two federal Fisheries Act charges after millions of fish died in the plant's cooling water intake system in 2025.

The charges against Bruce Power come after a CBC News investigation revealed publicly, for the first time, the extraordinary scale of what happened.

An estimated 8.1 million gizzard shad massed near the power plant during a sudden cold snap on Feb. 13, 2025, according to an internal report from Bruce Power. The small, cold-sensitive fish were drawn to the warm water discharged into Lake Huron near Tiverton, Ont., by the nuclear power plant over a two-month period, between February and March of 2025.

The fish subsequently became trapped and died against the plant's intake screens in such large numbers that one reactor had to be shut down and another had to reduce power, straining the province's electrical grid during a prolonged winter cold spell.

The company's own findings said the massive fish kill was the result of an "organizational failure" to adapt to changing environmental conditions caused by climate change.

Dead gizzard shad lie along the Thames River in 2021. The same temperature-sensitive species washed ashore along Lake Huron for days during the 2025 fish kill at Bruce Power. (Colin Butler/CBC)

Fisheries and Oceans Canada (DFO) estimates between 3.3 and 4.3 million fish died between February and March of 2025 — more than 200 times Bruce Power's annual authorized limit by weight.

Gizzard shad carcasses washed ashore in nearby communities for days, while Bruce Power used a crane to scoop millions of dead fish from the plant's cooling water channels before hauling them to a landfill, provincial records showed.

Under the federal Fisheries Act, Bruce Power was charged last month with causing the death of fish through non-fishing industrial operations and violating the conditions of its environmental permit, which limits the company to 6,600 kilograms of dead fish annually.

"As this matter is before the courts, we cannot comment on how we intend to plead or provide additional commentary relating to the charges," Megan Adams, Bruce Power's director of corporate communications, wrote in an email.

The company will appear in Ontario provincial court on Nov. 24.

Fines pay for environmental restoration

In a recent news release, Bruce Power said it was transparent with regulators, including DFO and the Canadian Nuclear Safety Commission, as well as nearby First Nations and municipalities about the fish kill.

An aerial image of the Bruce Power site located near Tiverton, Ont. (Submitted by Chad Richards)

Still, prosecutors don't have to prove the company meant to kill fish in order to establish an offence, according to Theresa McClenaghan, a lawyer and the executive director of the Canadian Environmental Law Association (CELA).

"The courts consider Fisheries Act offences to be serious offences," she said.

Fines for a first offence can range from a few thousand dollars to $200,000, she said, and are intended to deter violations and express the court's condemnation.

When a fine is issued by the court, the money goes into the federal Environmental Damages Fund to support conservation, habitat protection or restoration, McClenaghan said.

The court can also recommend directing the money to a particular organization or project, including an Indigenous nation or for environmental research.

'A giant fish trap'

Since the fish kill, Bruce Power has spent more than $10 million on mitigation measures, including nets to keep fish out, acoustic and strobe-light deterrants, sonar, cameras and artificial intelligence to monitor fish movements, along with expanded lake research.

WATCH | Fish gather in the warm waters off Bruce Nuclear Station:

Rare 'fish city' footage reveals hidden world

May 9|

Duration

2:01

Using a $250,000 underwater drone, documentary filmmakers Yvonne Drebert and Zack Melnick are capturing footage from parts of the Great Lakes that are often too deep or remote to observe directly.

Ryan Lauzon, a fisheries biologist who advises Saugeen Ojibway Nation, whose traditional territory includes the nuclear plant, said during a recent onsite visit last year he saw gaps in the mitigation measures.

"I did see fish that were swimming right up to that sound and acoustic deterrent system. There was gaps in the nets that were being used to exclude the fish. They ended up having to take the net out because they were so full of algae and dead fish."

Invasive zebra and quagga mussels have depleted the plankton that supports Lake Huron's food web, Lauzon said, leaving less food for other species and making the loss of millions of gizzard shad concerning. They are a prey species for trout, pike and walleye.

Lauzon, who has written a paper on the fish kill, said smaller die-offs happened at the plant in 1977 and 2023. He said while Bruce Power may have spent millions on mitigation measures, they don't address the warm-water discharge that attracts the fish in the first place.

• Rare footage reveals 'fish city' near an Ontario nuclear plant on Lake Huron
• Lake Huron's 'fish city' is a sign of trouble at nuclear plant, says Ontario First Nation

"Unfortunately, the plant acts as a giant fish trap," he said. "Until we establish the effectiveness of mitigation measures and try to deal with this attractant issue, I still think there's real danger."

The cooling systems that draw those fish also face growing challenges as the climate changes, said McClenaghan, who noted the incident may point to a need to rethink how nuclear plants are cooled in a changing climate.

"On the list of possibilities are cooling towers or cooling loops as opposed to what happens right now," she said. "The lakes are acting as a heat sink."

ABOUT THE AUTHOR

Colin Butler is based in London, Ont., where he reports for Ontario and national audiences. He covers investigative, science, public policy and government accountability with a particular interest in using public records to uncover hidden stories.