Cold Harbor Brook is a medium-sized tributary of the Assabet River that flows out of Rocky Pond in Boylston. The brook flows under Central Street and Reservoir Street before entering Northborough, where makes its way along Church Street and under I-290.

The area surrounding Cold Harbor Brook along Crawford Street from Church Street south to West Main Street is owned by the Department of Environmental Management and is maintained as a flood plain. The hayfields are still mown in the northern part of the area.

Cold Harbor Brook Flood Control conservation property is owned by the Massachusetts Department of Conservation and Recreation. It is 231 acres. This property is open to the public.

The AllTrails website has a description and map of a hike at Cold Harbor Brook.