Lakefront homeowners in Sudbury denied permission to use herbicides to kill an invasive plant species

For nearly a decade, homeowners along Long Lake, in Sudbury, Ont., have been dealing with an invasive species called Eurasian milfoil.

The aquatic plant competes with native plants, reducing biodiversity and also reduces oxygen levels in the water, which can lead to fish dying..

Thick mats of Eurasian milfoil can also get in the way of recreational activities like swimming, boating and fishing. 

To try to control the growth, the city put weevils into the lake, in the hopes the insects would eat the annoying milfoil. But that wasn’t successful.

More recently, some lakefront homeowners applied to the Ontario Ministry of the Environment for a permit to use a herbicide called Diquat to kill the plants.

But around 30 neighbours, along with the Long Lake Stewardship Committee, opposed the plan.

“It is a very controversial issue to be putting chemicals into the lake, particularly when the majority of the people living on the lake use the water as their drinking source,” said Scott Darling, chair of the Long Lake Stewardship Committee.

Ultimately, the ministry decided not to grant permits for the use of the herbicide in the lake.

“There is no magic bullet at this point in time,” Darling said about managing the Eurasian milfoil.

“Herbicides are a possibility, but we recommend extreme caution when considering using aquatic herbicides in our lakes here in Sudbury.”

Darling says there are around 20 lakes in Greater Sudbury that have the invasive species.

The Greater Sudbury Watershed Alliance has been looking at different options to remove the plant from those lakes. 

“We’re hoping that we can come up with something to solve the problem,” Darling said, noting they had a recent meeting with Fisheries and Oceans Canada to discuss possible solutions.

Vicki Simkovic, a co-ordinator with the Ontario Invasive Plant Council, says Diquat is a broad spectrum herbicide, which means it kills all aquatic plants where it’s applied, not just Eurasian milfoil.

When it’s applied to the water, Simkovic says people have to avoid swimming in that area and drinking the water for at least five days.