Clint Goyette has spent a lot of time on the rivers around Squamish, B.C., over the last two decades as a fishing guide, but even he was shocked to see hundreds of dead fish lying in pools along the Cheakamus River recently.

The spawning pink salmon, on their way to lay thousands of eggs, became trapped in isolated pools and died as water levels in Cheakamus River rapidly fell — the result of a nearby BC Hydro facility decreasing the river's flow, known as ramping, at the end of September.

"I was out guiding the day of the [river level] reduction," said Goyette, who runs Valley Fishing Guides in Squamish, about 65 kilometres north of Vancouver.

Goyette said he ran into BC Hydro crews out on the river surveying the damage, one of whom warned him about what he was about to encounter further up the river.

"I passed one of their crew … and he said, 'There's hundreds of dead fish up there so don't be surprised,'" Goyette said.

BC Hydro said the company had to lower the river levels because of public safety concerns at a nearby facility. A spokesperson said the timing coincided with a later-than-usual spawning season. (Chessy Knight )

Biologist Chessy Knight, who captured photos of the dead fish on Sept. 20, estimates about 300 fish were killed when the water levels in the Cheakamus River fell by about half over the course of a day.

The pink salmon were trapped in shallow pools and couldn't return to deeper, flowing sections of the river.

"This has been happening for many, many years on the Cheakamus," said Knight, who's also president of the Squamish River Watershed Society.

"But this is the first time that we saw adult spawners also affected by these flow manipulations."

That's significant, she said, because those spawning salmon never had a chance to lay their eggs and produce much-needed offspring.

'We take it extremely seriously'

BC Hydro is aware of the issue and acknowledges responsibility.

"It was unexpected. We thought that by lowering the levels at the rate we did, the salmon would not be stranded and would be able to find their way to deeper water in time," said spokesperson Geoff Hastings.

BC Hydro runs a nearby power facility and is allowed to increase or decrease the water flow in the river as needed. Hastings also noted that this is not the first time fish have been stranded as a result of ramping.

According to Hastings, the company had to lower the levels in September because of public safety concerns — and that the facility has to balance safety, environmental protection and energy generation.

"We take it extremely seriously," Hastings said. "We don't want to be stranding fish and we are trying to learn from these events and then hopefully not do it again."

Anglers fishing in the Squamish River earlier this summer. (Francesca Knight)

'Not sustainable'

Knight said BC Hydro should have known better and waited for the spawning fish to get to safety.

"BC Hydro should have just left the river alone until we got the big fall rains," she said.

BC Hydro's water licence, which allows it to control the river flows, is currently undergoing a government review.

Knight said her group is advocating for slower rates of ramping and more water to be left in the river in order to avoid stranding fish.

"There's this common perception that hydroelectric power is harmless but ... it is not harmless. It is not without impact," she said.

"We should have hydro as part of our clean energy portfolio, but the way it's being done is not sustainable."