Manitoba revokes herbicide permit for retention ponds

If you notice that your Winnipeg retention ponds are a little cloudier than normal, there may be a reason.

According to the city of Winnipeg, the province has revoked the permit for the herbicide, a chemical called “Reward.”

It is noted that Manitoba will not approve another chemical for vegetation control. It is also noted that the permit was revoked due to a discrepancy in labeling.

In a statement, the province said the Reward label allows for its use in open waters, including retention ponds that feed into fish-rich waters. However, the province noted, the federal Fisheries Act does not allow for the use of pesticides in fish-rich waters unless they are used to control invasive aquatic species.

The province said it sent a letter in May 2024 clarifying the requirements for municipalities and had also spoken to Health Canada about the matter.

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

The city says there are concerns about water quality and wildlife.