City drains 2 northwest Calgary ponds due to dumped goldfish

The city has drained a northwest pond as invasive fish have been dumped into it something a spokesperson says is a widespread issue affecting the majority of Calgary's ponds.

A metal fence now surrounds a ravine in Edgemont that used to contain a wetland storm pond.Edgemont resident Dario Rossi said it went up around Christmas with a sign saying the city is draining and freezing the pond to try to get rid of invasive goldfish and Prussian carp.

"Apparently that's pretty common, that people have a goldfish and then it's not fun anymore and so they think they're doing the goldfish a favour by putting it in the pond. But then they breed like crazy," Rossi said.

Corey Colbran, the city's manager of wastewater and stormwater collection, says there are more than 200 ponds within Calgary'sstormwater collection system, and most of those ponds have invasive fish in them.

"It's a lot of them. Probably approaching all, but I couldn't put a specific number on it," Colbran said.

He said many people don't realize that dumping the fish could eradicate native fish populations in the Bow River and he said it's a widespread issue across the province.

"We've got some world class fishing on the Bow, and we certainly don't want it out competing the native species that live in the Bow River habitat," Colbran said.

He added that some people don't fully understand the impact that the invasive fish can have when released into the wild.

"They might flourish in the pond, and they certainly do, which is part of the problem because ultimately what happens if they make it to the Bow River they can start to outcompete the native species."

Draining part of new initiative

Colbran said the pond draining in Edgemont is part of a pilot project to see if the city can reduce the number of invasive fish entering the Bow River.

The city is also draining a pond in the northwest community of Tuscany.

While the fish are killed in the draining process, it doesn't affect nativespecies, which aren't found in the ponds. The stormwater flows out to the Bow, but not back into the stormwater system.

Colbran said Prussian carp burrow into the pond's sediment, so by removing the water, the city is trying to freeze the bottom of the pond, including any potential eggs that are down there.

But he says it won't be easy, because these fish are hardy, and the city won't know if they were successful till the snow melts and the ponds fill back up in spring.