Epcor pauses planned cull of invasive goldfish in west Edmonton stormwater pond
Emily Williams | CBC | Posted: August 23, 2024 12:00 PM | Last Updated: August 23
Glastonbury residents complained about plan to use chemical pesticide rotenone
Epcor and Alberta Environment are pausing a chemical treatment for invasive goldfish in west Edmonton's Glastonbury neighbourhood, after residents expressed concern it isn't safe.
Up to 25 centimetres long, goldfish in stormwater ponds are often controlled by spraying a pesticide called rotenone — which Epcor says, is the most effective method with no long-term adverse effects. But Glastonbury residents were not convinced.
"As we dove deeper into it, we became even more concerned not only for the people that lived in our immediate community and what they were planning on putting in the water, but also for the environment we live in," resident Brad Margolis told CBC's Edmonton AM.
WATCH | Pesticides to stop invasive goldfish raise concerns:
Dr. John O'Connor, a physician and water advocate formerly based in Fort McMurray, has lived in Glastonbury since 2015. His concern grew after reading the Epcor flyer which said the treatment was safe, but would be applied by a team in hazmat suits, and that residents should move all yard items 10 metres back from the waterfront before application.
"It was all contradictory," he said. "We did our own due diligence. We're a group of six in the neighbourhood — we're very concerned."
In addition to concerns over manufacturer toxicity labels, O'Connor cited a study that found rotenone has links to Parkinson's disease, which left him worried.
The chemical is approved for use by Health Canada and Alberta Environment and Protected Areas (AEPA).
According to the flyer from Epcor, the fish are often introduced to an ecosystem as discarded pets — after which they thrive, reproducing quickly. It is treating another pond in Terwillegar this summer and has plans to treat two others next summer.
The group of residents has met with Epcor and AEPA to discuss their concerns. While they successfully got Epcor to delay the spray, resident Gary Boehm said it hasn't been transparent.
"They never changed to be fully open, fully honest, fully transparent with the people.
"We've passed a lot of information off to the citizenry, which we feel should have been the obligation of Epcor — they dropped the ball on that."
Epcor said it has done regular updates for residents through flyers and in-person meetings.
Greg Goss is a professor of biology at the University of Alberta and the president of Aquosity Environmental Consulting. He says the rotenone treatment shouldn't impact human health, since stormwater ponds aren't used for drinking water, swimming, or recreational use.
"That said, it's not going to solely impact fishes … you could end up infecting invertebrates like crayfish and small little bugs that exist in the community's ecology."
Goss added that stormwater ponds aren't supposed to have fish in them at all. Glastonbury residents, however, said their stormwater pond was integrated into a pre-existing wetland in the area — which means it's a more diverse ecosystem and landing place for migratory birds.
"It will degrade over time in sunlight so it's not a persistent chemical," Goss said. "It's been in use for quite a while as a pretty blunt force mechanism to get rid of something like invasive species."
While Goss said it's essential to eradicate invasive species, he's not familiar with rotenone's effect as a secondary toxin — meaning a chemical that moves up the food chain as birds eat treated fish. Epcor said this isn't an issue, as the rotenone will break down in their digestive systems.
The treatment has already been successfully used in other stormwater facilities in Edmonton, including Keswick and Donsdale, Epcor said in a statement to CBC. A total of four ponds were treated, with no required follow-up treatments.
The group of residents hope the pause will last at least one year to explore the impacts and potential alternative solutions.
Epcor is required by AEPA legislation to eliminate invasive fish. Dale DeBock, Epcor's senior manager of wastewater collection, said the pause will give AEPA time to review residents' concerns — but that decision will be made soon.
"There's a finite window for us to be able to do this treatment and for it to be effective," he said, adding that it needs to align with spawn times and warm weather.