MWRA online - home
About MWRA
Water System
Sewer System
Harbor and Bay
School Program
About MWRA
Doing Business with MWRA
Contact MWRA
Watershed Protection
Massachusetts Water Resources Authority

A watershed is the total area that drains directly across the land and indirectly through the groundwater, to a particular stream, river, pond or reservoir. Precipitation that falls anywhere in the watershed of a given reservoir or stream will eventually end up in that body of water.

We protect watersheds because all activities within them have impacts - some small, some great - on their water quality.

MWRA's Watersheds
watershed map


A History of Protected Source Waters

The best way to deliver clean, safe water is to start with high quality source water. Since the 1870s, planners have sought relatively pristine and protected water sources for metropolitan Boston, ones that would require minimal water treatment. Historically, ever larger and more distant reservoirs have been secured in central and western Massachusetts to supply both the quantity and the quality of water needed. As a result, MWRA inherited in 1985 a water system whose sources - the Wachusett, Quabbin and the Ware River - are the least polluted available and require a minimal level of treatment - disinfection and corrosion control.

MWRA and Department of Conservation and Recreation Watershed Protection efforts continue this heritage by assuring that the quality of the source water is as high as it can be.

MWRA Source Waters
Quabbin Reservoir 412 billion gallons
Wachusett Reservoir 65 billion gallons
Ware River Amount varies: Water can be drawn from the Ware River if needed. When the Ware River flow is above 85 mgd during the period from October 15 to June 15, withdrawals are sent to the Quabbin Reservoir.

Protecting Backup Supplies

In addition to its source reservoirs, MWRA maintains backup water supplies throughout the metropolitan area. While these waterbodies do not have to meet stringent daily drinking water quality requirements, they are kept on standby status to be used in case of emergency.

MWRA Back Up Supplies
Sudbury Reservoir 7.3 million gallons
Foss Reservoir 1.2 million gallons
Norumbega Reservoir 205 million gallons
Chestnut Hill Reservoir 522 million gallons
Spot Pond Reservoir 1.8 million gallons

Once water has been treated at the Carroll Water Treatment Plant in Marlborough or the Brustch Water Treatment Facility in Ware, it is transported by aqueducts, tunnels and pipelines towards users. Along the way, it is stored in covered storage reservoirs and tanks to balance the demand from high and low periods of use each day. The water is safely protected all the way from the reservoir, through treatment and covered storage on its way to the user.

MWRA Treated Water Storage Facilities
Norumbega 115 million gallons
Carroll 45 million gallons
Nash Hill 25 million gallons
Fells 20 million gallons
Loring Road 20 million gallons
Arlington 2 million gallons
Bear Hill 6 million gallons
Bellevue 3.7 million gallons
Turkey Hill 2 million gallons
Walnut Hill 2 million gallons
Spot Pond 20 million gallons


Further Reading

MWRA's Integrated Water Supply Improvement Program

Source Water Assessment and Protection Report

Sudbury Reservoir Watershed Protection

EEA/DCR Water Supply Protection Trust

DCR/DWSP: Massachusetts Department of Conservation and Recreation
Division of Watershed Protection

DCR Wins National Clean Drinking Water Award [PDF]

DCR/DWSP Water Quality Reports


DCR/DWSP Fact Sheets and Newsletters

Updated January 21, 2021