Northlands Pond is completely fenced off while three departments within the City of Medicine Hat complete work.--NEWS PHOTO SAMANTHA JOHNSON
reporter@medicinehatnews.com
Northlands Pond within Viterra Park in the city’s northeast is fenced off while three City of Medicine Hat departments complete work – parks and rec, municipal works and environment, land and gas production. The fence will likely come down sometime in mid-October.
“From the city’s perspective, we saw the opportunity to lower the water level one time,” said biologist Joel Wagner, environment specialist with environment, land and gas production, as part of the Environmental Strategy and Compliance team. “This will allow the parks department to do a control of the cattails on the north side of the pond, which is already done. Municipal works will complete maintenance of the stormwater infrastructure and the pond will refill itself in the spring.”
Wagner and team are dealing with a goldfish problem in the pond, likely the result of someone releasing aquarium fish. While the original population is unknown, they’ve multiplied exponentially.
“Now there is a significant population in the pond, and from a regulatory perspective we need to remove the fish to prevent them from gaining access to the South Saskatchewan River through the underground storm sewer network,” explained Wagner.
The city received two notifications about the goldfish and won’t know if any other species are present until removal is complete. As goldfish are hardy, the stormwater pond will be treated twice with Rotenone. Other areas in Alberta have tried to freeze the fish, but goldfish can survive in both low oxygen and cold conditions.
“Goldfish will bury themselves in the mud and it only takes one or two fish to survive to redo the whole population.”
As Northlands Pond is a storm water retention and settling pond, it is supposed to be fish free.
“The storm sewer for the area drains into this pond. It will settle out turbidity, sediment and contaminants, and when the pond reaches a certain level it will overflow into the storm sewer network. From there it joins up to the South Saskatchewan River.”
The pond is not completely being drained, about a metre of water will remain for ducks, bugs and other species that use the habitat. The pond will receive two treatments of Rotenone. The first will target fish currently alive in the pond and the second is for any that spawned from eggs between treatments.
“Because there is not supposed to be any fish in this pond, and there are no native fish, we are able to use this pesticide because the only thing that will be affected is the fish,” stated Wagner. “Any other species that would be trying to compete in here with those fish are not going to compete well because there are so many, they will outcompete everything for the available resources.”
Leinweber Pond at the top of Scholten Hill was treated with Rotenone last year. The treatments are time consuming and expensive due to the amount of regulatory applications and planning required. Additionally, the area must be fenced off and treatments done by a qualified biologist.
“People in town, please don’t release your fish,” urged Wagner. “If you have goldfish that you can’t take care of, contact your vet. The parks and recreation office also has fish disposal pods that are available free of charge that residents can pick up.
Goldfish constantly stir up turbidity in a pond, which reduces water quality and available oxygen. The whole ecosystem can be out of balance due to the sheer quantity of goldfish consuming available resources.
“When they are small, they aren’t gold,” explained Wagner. “It’s not until they get larger that you can see them as goldfish. There have been goldfish that have been pulled out of other ponds in Canada that have been the size of dinner plates. In this pond, I haven’t seen any that large, but we won’t know the size and extent of the fish until we complete the treatment. For perspective, last year at Leinweber Pond, which is approximately half the size of this pond, they pulled out over 250 lbs of goldfish.”
More information is available at https://www.medicinehat.ca/en/news/rejuvenation-underway-at-northlands-storm-pond-in-viterra-park.aspx.
