Stoney Brook used to pass under the old Worcester Turnpike so, when it was flooded, a good chunk of the old stagecoach road went under water. This led to a rerouting of what is now Route 9 along the South shore of Reservoir Number Three.
Gothic Victorian gate houses were built on each reservoir's dam and also on Farm Pond, which was tapped and linked to the network.
A conduit brought the water (by gravity) to the Chestnut Hill Reservoir, which in turn could bring the "pure" water to the faucets of Bostonian homes. In the late 1800s, most of the water used in Boston came from Lake Cochituate and the Sudbury River System. When the Quabbin Reservoir was built in the 1930s and 40s, it became Boston's main water supply, relegating the Sudbury River System to an emergency water source. Today, the Framingham reservoirs are pretty much offline. The Sudbury Reservoir and Reservoir Number Three are emergency backup supplies. For more information on Boston's water supply history, please have a look at Metropolitan Boston's Water System History.
The Sudbury river in its South to North course becomes Reservoir Number Two (Brackett) and then the larger part of Reservoir Number One before veering East (below Framingham Centre) and then North on its way to Saxonville. The Stoney Brook, coming from the West, becomes Reservoir Number Three before going into what's left of the Sudbury river at Reservoir Number One. A small piece of the Sudbury Reservoir (7 billion gallon capacity) can be seen in the North-West corner. Thanks to googlemaps.
Gate house at Reservoir Number Three's dam right along Route 9.