City contractors poured pesticide into Riel Pond Friday morning, killing most of the fish within to get at a spiny invader.
Contractors with Blueweed Services Ltd. and Focus Corp. made the decision to apply the pesticide Rotenone to the stormwater pond at about 6 a.m. Friday morning, says Leah Jackson, the city’s environmental manager. The application had been delayed three days due to wind and rain.
Rotenone is a pesticide harmful to fish but harmless to birds, pets and people. The city has decided to use it to eliminate the invasive threespine stickleback from the pond. Screens on the pond’s outfalls are meant to keep those fish in, but they’ve clogged repeatedly, creating a flood risk. The rotenone is meant to kill the stickleback so the screens can be removed.
Contractors used a Zodiac to pump the pesticide into the lake, Jackson said, starting with the edges and then cruising around the interior. After waiting for the chemical to take effect, a second group in a rowboat collected the dead fish floating on the surface. Crews were finished by the afternoon.
The city gave notice that it would use the pesticide in late April. A fish survey of Riel Pond did not find any threespine stickleback in the lake on Monday, but regulators said that was not enough proof to guarantee that they were gone.
City staff will test the pond next week to track the pesticide’s degradation, Jackson said. Once it’s gone, they will remove the plugs on the pond’s outfalls so it can drain and do a second fish survey to see if the sticklebacks are gone. “Once those results are reviewed with Fish and Wildlife and DFO [Department of Fisheries and Oceans], we’ll have permission to take the screens off.”
Ludo Bogaert, a local naturalist at Riel Pond Friday morning, said he didn’t agree with the city’s actions. “I think that the threespine stickleback are also in the [Sturgeon River] system because of the earlier years,” he said, referring to the fact that the sticklebacks were in the pond before the screens were installed. He also worried about how the chemical would affect birds.
“I think the whole thing is a political thing just to take the screens out.”
For details, call the Office of the Environment at 780-459-1746.