City officials plan to use pesticides on Riel Pond within two weeks to get rid of an invasive fish.
City staff announced this week that they will use Rotenone on the pond to eliminate the three-spined stickleback. The stickleback, a mottled-brown minnow with three big spines on its back, is an invasive species that has caused the city headaches for years.
The city originally planned to use the chemical last fall, but the pond froze before they could.
Now that the pond has thawed, the city is in a position to start applying the chemical. "We have all the permits in place," said Leah Jackson, the city's environmental manager. "We're waiting for the right [weather] conditions to apply the Rotenone, which look favourable for the next few weeks."
Quick operation
Rotenone is a pesticide that kills fish by blocking oxygen absorption, according to fisheries biologists. It has no effect on birds, mammals or people. Its last reported use in St. Albert was October 1999.
Riel Pond is a stormwater pond next to Ray Gibbon Drive. The federal government ordered the city to put fine screens over the pond's two outfalls years ago in order to keep three-spined stickleback in the pond out of the Sturgeon River. Those screens have clogged continuously, creating a flood hazard. The city wants to remove the screens so the pond works properly, but to do that, they have to get rid of the stickleback.
Jackson told the environmental advisory committee about the upcoming Rotenone use at a meeting Thursday.
A biologist will survey the lake within a few days to confirm the presence of the fish before they started applying chemicals, Jackson said. In the unlikely event that the fish are not there, the city will discuss its options with the federal government.
The chemical could be used any time after that, Jackson said — it's up to the contractor to determine when conditions are right. "If it's perfect on Monday, he might go on Monday." The contractor will put up signs about the application around Riel Pond at least 24 hours before it happens.
"The day they do it, it's going to be very intense and like clockwork," Jackson said. "It's a one-day thing."
Once staffers seal the pond's two outlets, contractors will move in with boats to pump the Rotenone directly into the water. Dead fish are expected to float to the surface soon afterward; workers will collect them for disposal.
Residents will be able to use the trail by the pond while this is happening, Jackson said, but are asked not to disturb the contractors while they work. Certain areas may be barricaded off for safety reasons.
Once the application is finished, the city will track pesticide levels in the water to make sure it degrades properly. They will also do additional assays to confirm the stickleback are gone, and will likely restock the pond with native fish. If the government approves, the screens should come off the pond sometime in May.
Controversial decision
The environmental advisory committee is still split over the decision to use Rotenone, said committee chair Jason Cooke. Some members are philosophically opposed to killing all fish in the pond to get rid of one pest; others see it as a necessary step to getting the pond working. "There is at this point a grudging acceptance that it's going to happen," he said. "This is the method of last resort."
Cooke hoped this would resolve the stickleback problem once and for all. "If this doesn't turn out to be the end of the story, I'll be very disappointed."
Any questions should go to the Office of the Environment at 780-459-1746.
