The Coast Guard and Massachusetts Department of Environmental Protection responded to a dielectric oil leak Friday in the Mystic River near the Alford St. bridge.
The source is believed to be a small, slow leak from a cable under the river.
Initially, Mass DEP and a pollution response team from Coast Guard Sector Boston discovered a notable rainbow sheen during a routine patrol of the river.
Boom was deployed around the sheen, and later, an investigation determined the probable source was a cable encased in a metal pipeline which runs under the river.
The exact location of the leak along the pipe has not yet been identified. Both agencies, along with NOAA’s Scientific Support Coordinator, are working to pinpoint the source, determine the responsible party, continue to boom off the area, and are patrolling the waterway and shoreline for signs of pollution.
“We are working diligently with Mass DEP and NOAA to identify the location of the leak, stop it, and minimize any environmental impacts along the river,” said Coast Guard Cmdr. Brad W. Kelly, deputy commander of Sector Boston.
He said teams will continue to monitor for pollution throughout the night, dive plans are being evaluated and a first-light clean-up and assessment team will be on site early Saturday.