Manitoba revokes herbicide licence for Winnipeg retention ponds

Manitoba has revoked the licence for the herbicide Winnipeg uses in its retention ponds.

If you’re noticing that Winnipeg’s retention ponds are a bit cloudier than usual, there may be a reason for that.

According to the City of Winnipeg, the province revoked the licence for its herbicide, which is a chemical called ‘Reward.’

It notes there is no other chemical Manitoba will approve for vegetation control, adding that the licence was revoked due to a discrepancy in the label statements.

In a statement, the province said the label for Reward permits its use in open bodies of water, including retention ponds that drain into fish-bearing waters. However, it notes, the federal Fisheries Act does not allow the use of pesticides in fish-bearing waters unless it is being used to control aquatic invasive species.

The province said it sent a letter in May 2024 to clarify the requirements for municipalities, adding that it has also met with Health Canada on the matter.

Winnipeg said the mechanical harvesting of vegetation is now its only option to reduce vegetation in retention ponds. However, it notes, this is not an option for all ponds based on shape, depth and access.

The city said there are no concerns for water quality or wildlife.