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The Sewer System
Massachusetts Water Resources Authority

 

MWRA's sewage treatment system has undergone a nearly complete transformation under the federally mandated 11-year, $3.8 billion Boston Harbor Project. The project, which is now complete, included a new sludge-to-fertilizer facility; the Deer Island Treatment Plant with primary and secondary treatment capabilities; the Inter-Island Tunnel that tied together two separate sewer systems (North and South) into one; and the 9.5-mile Effluent Outfall Tunnel to discharge treated wastewater away from shallow Boston Harbor waters and into the deeper waters and stronger currents of Massachusetts Bay.

Aerial of Deer Island

DEER ISLAND WASTEWATER
TREATMENT PLANT

The centerpiece of MWRA's
Boston Harbor Project

 

HOW THE SEWER SYSTEM WORKS
How the Sewer System Works
History of the Sewer System
SEWER TREATMENT FACILITIES
Deer Island Wastewater Treatment Plant

       Tours and Public Access

       Renewable Energy at Deer Island
       Effluent Outfall Tunnel

      Wastewater Testing - Laboratory Services

Clinton Wastewater Treatment Plant
Nut Island Headworks
MWRA SEWER PROGRAMS
Combined Sewer Overflow Program
Sanitary Sewer Overflows (SSOs)
Toxic Reduction and Control (TRAC)
       Permit Applications
       A Healthy Environment Starts at Home Booklet (PDF)
       It's A Toilet, Not a Trash Can! What Not to Flush
              "What You Flush Matters" Brochure (PDF)
Community Support Program: Infiltration/Inflow (I/I) Reduction
Sludge to Fertilizer Program
       Bay State Fertilizer
       The Fore River Railroad
SEWER INTERCEPTOR PROJECTS
Braintree-Weymouth Relief Facilities Projects / Fore River Siphons
Framingham Extension Sewer Repairs (PDF)
Upper Neponset Valley Relief Sewer Project (West Roxbury)
West Roxbury Sewer Section Rehabilitation
ADVISORY GROUP
Wastewater Advisory Committee (WAC)

Updated December 13, 2021