The process of eradicating goldfish from the Drake Landing storm pond in Okotoks started last week.

The overpopulation of the goldfish resulted from residents illegally dumping the fish into the Drake Landing and Crystal Ridge storm ponds which now pose a threat to the Sheep River's ecosystem.

A chemical called rotenone was used which only kills organisms that have gills.

Christa Michailuck, parks manager for the Town of Okotoks, says the pond's depth was lowered by about a meter which resulted in a 50% decrease in volume so they could use 50% less chemical for the treatment.

"In order to give us some buffer in capacity, because we don't want the chemical to go back to the Sheep River, we lowered the pond level and closed the valve, then if we get rain events to bring the pond back up to the level where it does outlet back to the Sheep River that'll dilute the chemical sufficiently so there's no concern about chemical going back to the river."

While the rotenone isn't harmful to other animals or humans, the applicators required to wear personal protective equipment and respirators as they were in contact with more concentrated forms of the chemical and the strong odour could be dangerous to those who are handling the product.

Those who may have noticed the smell of the product from outside of the fence surrounding the pond were safe as it wasn't at levels to cause any impact.

Michailuck says a boat was required for a majority of the rotenone application.

"A pump will take pond water and a hose from the chemical bin, they'll mix together inside the pump, then the combined chemical/ water mix will be deposited under the surface of the water. To treat the fish in locations where the boat can't get to some spray application from the boat or shore may be required."

Crews were out performing clean-up of the Drake Landing storm pond last Friday.  The rotenone application for the Crystal Ridge storm pond scheduled to take place near the beginning of September.

The Town would like to thank Alberta Parks and the Conservation Association for their assistance.