Watershed Infrastructure

The Watershed Division manages a variety of critical infrastructure such as reservoirs, dams, gatehouses, conduit, maintenance facilities, and gaging stations. Click the links below to view infrastructure-related maps in the Cambridge Watershed.

Watershed Parcels and Infrastructure Map

Virtual Map Tour of the Cambridge Watershed

All Watershed Maps


The City of Cambridge owns four reservoirs: Hobbs Brook (593 acres) in Waltham, Stony Brook (74 acres) in Weston and Waltham, Fresh Pond (155 acres) in Cambridge, and the underground Payson Park (9 acres) reservoir in Belmont.

Click here for a map showing the reservoir locations. Learn more about Cambridge's reservoirs in Where Does Our Drinking Water Come From?

 An image of serene water on Hobbs Brook Reservoir and trees on the shoreline


Both the Hobbs Brook and Stony Brook Reservoirs were artificially formed in the 1890's by the construction of the two dams.  The Hobbs Brook Dam runs along Winter Street in Waltham and the Stony Brook Dam runs perpendicular to Gate House Lane in Weston.  Both dams are regularly inspected by Watershed Division staff and professional engineers to ensure dam safety.  Both dams have emergency spillways and sluice gates to allow large quantities of water to pass the dam in periods of heavy rain to ensure that the dam is not over-topped and structural integrity is maintained.

Grassy downstream dam slope and large outlet pipe of Hobbs Brook Reservoir


The City of Cambridge owns and operates three gatehouses. The Trapelo Road Gatehouse, located in Lincoln, allows water to pass through a sluice gate from the upper and middle basins of the Hobbs Brook Reservoir into the lower basin. The Winter Street Gatehouse, on Winter Street in Waltham, allows water to safely pass through the dam into Hobbs Brook.  This gatehouse has three sluice gates at different depths to ensure that the water drawn from the reservoir is of the highest quality.  Renovations to the two gatehouses were completed in 2012, which included the installation of new, electrically actuated gates. The Stony Brook Gatehouse, located on Gate House Lane in Weston, also has three sluice gates at varying depths so that the Water Department can control the elevation from where water is drawn. Renovations were made to the Stony Brook Gatehouse in 2000/2001 which also realized the installation of new electrically actuated sluice gates.

A red brick gatehouse building covered in snow on the Stony Brook Reservoir dam

A gatehouse structure on Fresh Pond Reservoir is no longer in use. Water is pumped directly from the reservoir for treatment in the purification facility.

Stony Brook Conduit

The Stony Brook Conduit is a 7.7-mile underground pipeline that carries water directly from the Stony Brook Reservoir to Fresh Pond Reservoir. The Watershed Division coordinates with the Distribution Division to manage the conduit. Continued assessment and maintenance of the conduit right-of-way ensures that Cambridge will have a continuous, easily accessible water source.

Maintenance Facilities

The Cambridge Water Department owns two barns used as storage and maintenance facilities in the watershed. The barn on River Road in Weston is used for maintenance and hazardous material response equipment storage. The barn at 167 Trapelo Road in Lincoln is also used for equipment storage and doubles as a staff field office.

CWD Staff Field Office at the Trapelo Road Barn in Lincoln

Gaging Stations

The Cambridge Water Department in cooperation with the USGS (United States Geological Survey) owns and operates 13 gaging stations throughout the watershed. These stations house equipment powering the continuous record surface water monitoring portion of the Source Water Quality Monitoring Program.