SWANTON — The Agency of Natural Resources (ANR) is aiding the Swanton Fire Department (SFD) in an ongoing attempt to cleanup and investigate a fuel oil leak.

Civilians first reported a “rainbow color” on the Missisquoi River, north of the Depot Street bridge, on Saturday afternoon.

The SFD has determined the oil is “bubbling up” under Smitty’s Starter & Alternator on Foundry Street, according to SFD Chief Tim Girard.

Girard said the source of the oil leak is still undetermined, though authorities suspect a migration issue from an old underground tank might have caused the leak.

The ANR joined in containment efforts after the SFD exhausted their resources, Girard said.

Emergency personnel are containing oil on the river through the use of water booms, a floating barrier that nets oil and skims it from the water’s surface.

Girard said there is no public danger, though he advised residents to avoid swimming in the affected area.