Deer Island Treatment Plant 100 Tafts Ave Winthrop, MA 02152 Phone : (617) 660-7600 Business Category Government Offices-State Legislative Bodies Mass Commonwealth Of Winthrop Chelsea, MA 02150 Phone : (617) 660-7600 Business Category Government Offices-City Village & Twp Water Supply Government Offices State & Local Government Offices & Public Schools Mass Commonwealth Of--massachusetts Water Resources Authority, Deer Island Treatment Plant, All Departments Winthrop Chelsea, MA 02150 Phone : (617) 660-7600 Business Category Government Offices-State Government Offices State & Local Government Offices & Public Schools