MWRA is a Massachusetts public authority established by an act of the Legislature in 1984 to provide wholesale water and sewer services to 3.1 million people and more than 5,500 large industrial users in 63 metropolitan Boston communities.

Thanks to the Quabbin and Wachusett Watersheds and Reservoirs, 2.5 million people and 5,500 industrial users have one of the most abundant and high quality water supplies in the world.

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.