(Reuters) - The Ontario government fined Imperial Oil C$900,000 ($641,391) for a slop oil leak into a tank containment area at its Sarnia site in 2021 that had an adverse effect on people.

Slop oil is a waste product that is typically composed of crude oil, water and waste solids and can contain various contaminants like hydrogen sulphide.

The Canadian company pleaded guilty under the Environmental Protection Act in a provincial court on Sept. 16, a spokesperson said, for an occurrence on April 15, 2021, where nearly 1,150 litres (7.3 barrels) of slop oil was discharged.

The discharge adversely affected people at two nearby businesses and residents of Aamjiwnaang First Nation, as per the court bulletin from Nov. 13.

Imperial has 90 days to pay the fine along with a victim fine surcharge of C$225,000.

"We regret this incident, and we accept the fine imposed by the court. Imperial has since made changes to its equipment maintenance plan by modifying the criteria used to prioritize repairs to mitigate the risk of a reoccurrence of the same incident," the company spokesperson said.

In August this year, Imperial - majority owned by Exxon - also had an administrative penalty of C$50,000 ($35,632) imposed on it due to a months-long toxic tailings leak at the oil and gas producer's Kearl oil sands mine.

($1 = 1.4032 Canadian dollars)

(Reporting by Seher Dareen in Bengaluru; Editing by Shailesh Kuber)