The Department of Conservation and Recreation (DCR), Division of Water Supply Protection (DWSP), Office of Watershed Management (OWM) and the Massachusetts Water Resources Authority (MWRA) currently supply drinking water to 51 communities, 2.5 million people and 5,500 industrial users in the metropolitan Boston area. DCR is responsible for collection and safe storage of the source water, protection of reservoir water quality, and management of the watersheds, while MWRA is responsible for drinking water treatment and distribution.


A watershed is a geographic area of land in which all surface and ground water flows downhill to common point, such as a river, stream, pond, lake, wetland, or estuary.




Quabbin Reservoir, the Ware River, and Wachusett Reservoir are the active water supply sources for the metropolitan Boston water system. Ware River water is transferred seasonally to Quabbin Reservoir, while Quabbin Reservoir water is transferred regularly to Wachusett Reservoir through the Quabbin Aqueduct. Wachusett Reservoir is the terminal supply reservoir of the Cosgrove Intake. Water is withdrawn through the Cosgrove Intake at the eastern end of Wachusett Reservoir, and is carried by the Cosgrove Tunnel to the MWRA distribution system. Quabbin Reservoir is also the terminal supply reservoir for 95,000 people in three Western Massachusetts communities (Chicopee, South Hadley Fire District #3, and Wilbraham) that obtain their water through the Chicopee Valley Aqueduct. The Sudbury and Foss Reservoirs are the emergency backup supply for metropolitan Boston.


Every aspect of this water supply system was considered an engineering marvel at the time of its construction. Both Wachusett and Quabbin Reservoirs were the largest man-made reservoirs in the world upon their completion. DCR/DWSP/OWM currently manages over 100,000 acres of land owned in fee by the Commonwealth specifically for water supply protection. The Office of Watershed Management also holds Watershed Preservation Restrictions (WPRs) on more than 2,000 acres of privately held property. Please click on each watershed below to view relevant facts and figures about each respective reservoir and its watershed.



Quabbin Reservoir Watershed      Ware River Watershed      Wachusett Reservoir Watershed    

  Sudbury Reservoir Watershed


Brief History of the DCR/MWRA Water Supply System 

During the nineteenth century, the Boston area obtained water mostly from Lake Cochituate in Natick, a reservoir completed in 1848. Some communities were also served by the Mystic Lakes. Officials determined that these sources of supply would prove inadequate. In 1878 a system of seven reservoirs was constructed to supplement the Cochituate system by holding back the Sudbury river.


Limited yield, urbanization of the watersheds, unsatisfactory water quality, and intrusion of sea water into existing well supplies led to the investigation for additional water supply of satisfactory quantity and quality. A study completed by the state health board in 1895 recommended the development of a reservoir along the South Branch of the Nashua River. Thus the Wachusett dam and reservoir were constructed by the Metropolitan Water Board (predecessor to DCR and its precursor, the Metropolitan District Commission) to use the Nashua River in central Massachusetts as a source of drinking water. The Wachusett Reservoir was completed in 1908.


To serve the growing needs of Eastern Massachusetts, the Quabbin Reservoir was created in the 1930s, using the Winsor dam to impound the Swift river and flood an area formerly occupied by the four Western Massachusetts towns of Dana, Enfield, Prescott, and Greenwich. In addition, the Ware River is used as a source of supply from October through June when flows in the river are sufficient and water is needed. Diversions of water from the river are conveyed into the Quabbin Reservoir through the Quabbin tunnel.


This information comes from Great Waters: A History of Boston's Water Supply, by Fern L. Nesson [University Press of New England: Hanover and London, 1983.]


Additional Information

  A History of the Development of the Metropolitan District Commission's Water Supply System  pdf format of A History of the Development of the MDC Water Supply
file size 3MB is a 1984 study by Wallace, Floyd Associates that contains a detailed history of the water supply system.


The MWRA website has an on-line historical timeline of the water supply system.