A Watershed is a term used to describe the area drained by a river and its tributaries.
|Kimball St. Dorchester Overflow 1896|
Boston has been using sewers since before 1700. The first sewers were privately owned and served the purpose of draining water from cellars and low lying areas into nearby surface waters. Problems arose due to the nuisance caused by constructing these sewers as well as disagreements over ownership rights. In 1709, the Massachusetts General Court passed an Act regulating the construction of sewers. The Act also provided the basis for distributing sewer costs and charging for their use.
Up to this point, water entering this system was from flooded cellars, yards and streets. In 1833, however, sanitary waste was allowed into the system. The practice proliferated throughout the city and in just one year later, the city encouraged adding rainwater from roofs to the system to assist in flushing the sewers of sanitary waste. This flushing did not solve the problem; and health issues, related to water contamination such as cholera, typhoid and dysentery, began to increase among Bostonians. In 1875, a study was initiated to address this problem, which led to the construction of the Boston Main Drainage System.
|Moon Island Reservoirs|
The Boston Main Drainage System (BMDS) was the original backbone of Boston's early sewer system. The BMDS was constructed from 1877 to 1884 under the direction of a special committee established by the City. The purpose of the BMDS was to intercept local sewers and carry the sanitary waste and rainwater runoff to an offshore disposal point. The system included: 25 miles of intercepting sewers, the Calf Pasture pumping station in Dorchester, the Dorchester Bay Tunnel and an outfall pipe at Moon Island in Boston Harbor. (It should be noted that neither the pumping station nor the tunnel is now in use.) As Boston's population grew and its city limits expanded due to annexation and land reclamation, the drainage works were subsequently enlarged to accommodate this growth.
|Construction of Stony Brook Channels|
The BMDS disposed of a substantial portion of the City's waste; however, there were parts of Boston lying outside the service area. To address this, the Metropolitan Sewerage System was form in 1889. The first of its kind in the country, the Metropolitan Sewerage District included: the North Metropolitan Sewer District, the Charles River Valley Sewer System and the South Metropolitan Sewer District.
In 1919, to oversee the complex Metropolitan Sewerage District (as well as the water system), the Massachusetts Legislature created the Metropolitan District Commission (MDC), now the Department of Conservation and Recreation. The Boston Main Drainage System, however, continued to be owned by the City. Up to this point, wastewater was merely collected and deposited into Boston Harbor. Because of worsening pollution, city planners recommended the construction of treatment plants before depositing the wastewater into the harbor. In response to this, the MDC constructed two primary wastewater treatment plants: the Nut Island Wastewater Treatment Plan in 1952 and the Deer Island Wastewater Treatment Plant in 1968. The outlet facilities at Calf Pasture and Moon Island were maintained as a backup for the Deer Island Plant during wet weather.
In 1977, ownership and operating responsibility for the sewer system (as well as the water system) serving the City of Boston was transferred from the City to the newly formed Boston Water and Sewer Commission (BWSC). And in 1985, Massachusetts Legislature was enacted that transferred the possession, control and operation of the MDC Water and Sewerage Divisions to the newly created Massachusetts Water Resources Authority (MWRA).
|Deer Island Treatment Plant|
Once in control of the system, BWSC began planned modifications and improvements. In 1988, construction of the New Boston Main Interceptor and the New East Side Interceptor were completed, replacing portions of the original BMDS. In addition, MWRA was also incorporating improvements to the system. Between 1997 and 2000, the MWRA upgraded the Deer Island Wastewater Treatment Plant from primary to secondary treatment, opened the Inter-Island Tunnel connecting Nut Island Wastewater Treatment Plant to Deer Island, thereby eliminating primary discharge from Nut Island, and completed the 9.5 mile Outfall Tunnel to move discharge from the confined waters of Boston Harbor to the deep waters of Massachusetts Bay.
Today, all wastewater collected by BWSC facilities is conveyed to the MWRA's Deer Island Treatment Facility for secondary treatment. BWSC's wastewater collection system serves approximately 20,500 acres. Visit our Present Day Sewer System page to learn more.