The Watertown Dam spans the

Charles River The Charles River ( Massachusett: ''Quinobequin)'' (sometimes called the River Charles or simply the Charles) is an river in eastern Massachusetts. It flows northeast from Hopkinton to Boston along a highly meandering route, that doubles bac ...

upstream from the Watertown Bridge near Watertown Square in Watertown,

Massachusetts Massachusetts (Massachusett language, Massachusett: ''Muhsachuweesut assachusett writing systems, məhswatʃəwiːsət'' English: , ), officially the Commonwealth of Massachusetts, is the most populous U.S. state, state in the New England ...

. The dam is located where the Charles River

tidal estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...

historically ended (the tides no longer reach this point because of the downstream Charles River Dam). Watertown Dam is of Concrete construction, a gravity dam. Its length is . Its capacity is . Normal storage is . It drains an area of . The history of the dam traces back to 1632 when construction of a fish

weir A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of l ...

was authorized. The current dam, maintained by the

Department of Conservation and Recreation The Department of Conservation and Recreation (DCR) is a state agency of the Commonwealth of Massachusetts, situated in the Executive Office of Energy and Environmental Affairs. It is best known for its parks and parkways. The DCR's mission is ...

, dates from 1900. It is part of the Upper Charles River Reservation.

Ecological impact

The Watertown Dam is the second of numerous dams located along the length of the

. The current earthen dam creates an obstacle for the river herring that run in the spring, but herring have long been harvested at this site. The Pequossette (one of the tribes of the Massachusett people) inserted stakes into the river then interwove brushwood to create a weir that would trap the herring as the tide went out. Today, a fish ladder provides access to upstream spawning habitat as part of a system of fish passages that provide access up to river mile 20. The high concentrations of

blueback herring The blueback herring, blueback shad, or summer shad (''Alosa aestivalis'') is an anadromous species of herring from the east coast of North America, with a range from Nova Scotia to Florida. Blueback herring form schools and are believed to m ...

and alewife below the dam in the spring make it a popular fishing spot for herring gulls,

great black-backed gull The great black-backed gull (''Larus marinus'') is the largest member of the gull family. Described by the Cornell Lab of Ornithology as "the king of the Atlantic waterfront", it is a very aggressive hunter, pirate, and scavenger. It breeds on ...

great blue heron The great blue heron (''Ardea herodias'') is a large wading bird in the heron family Ardeidae, common near the shores of open water and in wetlands over most of North America and Central America, as well as the Caribbean and the Galápagos ...

s, night herons and

cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the IOC adopted a consensus taxonomy of seven ge ...

s. File:Great Blue Heron readying to strike.JPG, Readying to strike File:Great Blue Heron catching Herring.JPG, Heron has fish under water File:Great Blue Heron spears Herring.JPG, Successfully speared File:Great Blue Heron with Herring.JPG, With herring

References

{{Crossings navbox , structure = Crossings , place =

, bridge = Watertown Dam , bridge signs = , upstream = Thompson Footbridge , upstream signs = , downstream = Watertown Bridge , downstream signs = MA Route 16

Dams in Massachusetts Buildings and structures in Watertown, Massachusetts Charles River Dams completed in 1900 1900 establishments in Massachusetts Crossings of the Charles River