About the Facility

The Westerly Wastewater Treatment Plant is an advanced wastewater treatment facility designed to handle a daily average flow of 2.89 million gallons per day. The facility treats sewage from the westerly portion of Marlborough (west of Route 495) and the Town of Northborough under an inter-municipal agreement.

The facility operates under a National Pollution Discharge Elimination System (NPDES) permit issued by the EPA and Massachusetts DEP.