Accident may have wiped out Larson Creek trout population
A construction accident at a provincial highway project may have wiped out a genetically distinct population of cutthroat trout in Larson Creek near Horseshoe Bay.
“It looks like a war zone, like you would see in the movies, with fish lying everywhere after a beach attack,” said John Barker, president of the West Vancouver Streamkeeper Society. “It’s a ghastly feeling to see that.”
Waste water from a pressure test by Keller Foundations at the site of a new overpass appears to have triggered an extinction event in the tiny creek, killing at least 76 fish.
“The cutthroat trout are resident to that creek, they never move in or out,” he said. “If they are all dead, and they appear to be, that could be it for Larson Creek.”
Their gills were fouled with fine material, Barker said. “There’s no chance they could survive that. They suffocate.”
The incident is being investigated by multiple government ministries and could result in charges under the Fisheries Act, if there is “sufficient evidence” of a violation, according to Environment and Climate Change Canada.
“I personally hope they are charged,” Barker said.
Inquiries about the incident to Fisheries and Oceans Canada were referred to Environment Canada.
Larson Creek is in a metal culvert through most of the construction site, but it is old and in poor condition.
The contractor disposed of water from the pressure test on site, but it unexpectedly caused erosion and flowed under the soil to the culvert and “turbid water” entered the creek, according to the B.C. Ministry of Transportation.
The water-disposal area has been stabilized and effective immediately, “all excess water will go through a treatment system before it is released,” the ministry said.
The project is covered by an environmental management plan and overseen by an environmental monitor, but “in light of the recent incident, these processes are being reviewed by the ministry to see if any further improvements can be made for the remainder of the Horseshoe Bay overhead project.”
The Larson Creek event is the third recent fish kill in local creeks observed by Streamkeepers.
About 50 fish were killed in nearby Woods Creek and several dozen dead fish were also observed in North Vancouver’s Mackay Creek. The cause of those events is not known.
The Woods Creek kill was discovered by a class from Eagle Harbour Elementary as they scouted the stream for a place to release their own aquarium-grown coho. Fish further downstream appear to have survived the incident.
“Without knowing what caused the Woods and Mackay kills, it’s hard to pinpoint the problem,” said biologist Alex Sartori, an environmental consultant and Streamkeeper member.