PORTLAND — State officials are investigating the source of 150 to 200 gallons of illegally dumped waste heating oil that city workers discovered in two stormwater catch basins at Falmouth and St. John streets.

Public works employees smelled noxious fumes coming from the storm drains on Tuesday morning and notified the police department and the Maine Department of Environmental Protection, city spokeswoman Nicole Clegg said today.

Police on patrol tracked the likely source of the waste oil to three empty, home heating oil tanks that were sitting on a flatbed truck at Schnitzer Steel, a metal recycling company on Riverside Street, Clegg said.

A Schnitzer employee told investigators that a person identified as Dominique Covington, who lives near the catch basins, had sold the tanks as scrap metal and was paid $69, according to DEP spokeswoman Samantha Depoy-Warren.

DEP staff members oversaw the removal of the heating oil from the catch basins and are investigating the incident further, Depoy-Warren said. Depending on the quantity and circumstances of illegal oil disposal, responsible parties may be fined, forced to pay for the cleanup and/or charged with a criminal violation of the state’s oil spill laws.

It is illegal to dump waste of any kind into storm drains, which are part of the city’s combined stormwater and sewage treatment system, which empties into Casco Bay.

Dumping flammable products into the storm drains created an added danger for homes and businesses in the neighborhood, Clegg said.