Algoma Central Corp has been fined $500,000 for discharging almost 45,000 litres of oily bilge water from a handysize bulker into Lake Ontario.

The 39,100-dwt Algoma Strongfield (built 2017) was crossing the lake in western New York state on 6 June 2017 when the captain authorised emptying the wash water tank, unaware that it was holding bilge water.

A month earlier, a Redwise Maritime Services crew were delivering the newbuilding to Algoma from China when the oily water separator and oil content monitor malfunctioned several times, causing a build-up of unprocessed oily bilge water.

On 5 May 2017, an Algoma employee told Redwise on several occasions to store the bilge water in the used wash water tank to avoid releasing it into the Pacific Ocean, according to a news release from the US Department of Justice (DOJ).

"The wash water tank was intended to store deck and cargo hold wash water and is not listed on the Strongfield’s International Oil Pollution Prevention certificate," the department said.

When the ship was delivered by Redwise to Algoma's homeport in Quebec, only some of the Algoma crew were advised of the bilge water in the wash water tank.

Algoma, which pleaded guilty to dumping the bilge water, declined to comment on the fine.

The company was also given a three-year probation, during which it must implement an environmental compliance plan.

“The Great Lakes are our nation’s largest source of freshwater, and this prosecution shows the administration’s commitment to preserving a natural resource that will be crucial for generations to come,” said Jean Williams, acting assistant attorney general of the DOJ's environment and natural resources division.