The Pine Tree Brook origin starts at the Hillside Pond near the intersection of Chickataubut Road and Hillside Street in the Milton Blue Hills. As the Hillside Pond fills, it runs over a small dam outlet that travels through stone conduit under Hillside Street and the brook begins to form at this location. It flows downhill snaking through the tree line; parallel to Unquity Road heading to the Unquity Dam at Harland Street. But prior to reaching the dam at Harland Street several streams that have developed during heavy rain intersect with the brook including water overflow from the Harland Conservation land that flows through a large pipe under Harland Street. This added water and the water from the brook then arrives at the dam.
During a heavy rain massive amounts of water form many streams that flow into the brook from the Blue Hills. (The Blue Hills is 635 feet above sea level and the tallest mass of land on the east coast.) At the Unquity Dam the overflow of water will back up to Harland Street’s conservation land. It is not unusual that the bottom of Harland Street is forced to close because of water.
This is when the Unquity Dam does its job as it was designed to do – slow down the excess of water during heavy rain from entering the Pine Tree Brook that feeds into Pope’s Pond.
As the water leaves the Unquity Dam it flows through a pipe under Unquity Road. A pond begins to form and forces the water by the Ulin Ice Rink and is directed by two large pipes keeping the water flow even as it heads towards Canton Ave. When it reaches Canton Ave. a drain pipe under the road directs it towards Pope’s Pond. The brook meets Trout Brook that has entered through another drain under Sumner Street and Peverly Park. The end of the drain then flows into the Pine Tree Brook. From this point, depending on the amount of rain, the brook is added to from several other overflows and the brook then enters into Pope’s Pond.
Pope’s Pond then begins to swell as other small outlets carry water into the pond. As the pond fills it then overflows a dam under the Pope’s Pond bridge heading towards a conduit that runs under the Blue Hills Parkway. The water is picking up speed as it heads to the bridge on Thacher Street.
As the water enters under the Thacher Street bridge it is met by a large cement canal; filling with water the canal slows down the fast driving brook during a heavy rain. The canal then directs the brook under Brook Road and then under Central Ave.
The brook then winds outside of the banks of Turner Pond. A large outlet that carries the overflow of water from Turners Pond adds to the brook. The brook continues around the Glover School and under the bridge at School Street flowing to the lower mills and under the Elliot Street bridge into the Neponset River.
As it enters into the Neponset River the Pine Tree Brook has carried a massive amount of water along its 10-mile route. There are many drainage pipes carrying water from streets and naturally formed streams (during high rains) that dump into the brook.