Imperial is investigating the cause of a spill into the St. Clair River last night.
Officials say water containing small amounts of diluted hydrochloric acid entered Imperial's water separator and then overflowed into the river.
The company says the release was discovered around 10:15pm and stopped 30 minutes later. Exactly how much entered the river is still unknown.
In a news release this morning, Imperial says no impacts have been identified downstream and water quality monitoring continues.
Both the Ontario Ministry of Environment and the Canadian Coast Guard were notified as well as downstream water users.
Hydrochloric acid is occasionally used at the site to help with cleaning process equipment.
