The Mystic Dam (and its gatehouse) are a historic dam and gatehouse between Lower and Upper

Mystic Lakes The Mystic Lakes, consisting of Upper Mystic Lake and Lower Mystic Lake, are closely linked bodies of water in the northwestern suburbs of Boston, Massachusetts. The lakes lie at an elevation of 1 meter above sea level, within the towns of Winch ...

in the suburbs north of Boston, Massachusetts. The dam was built in 1864–65 by the Charlestown Water Commission (Charlestown then being separate from Boston) as part of a water supply system. It was located at a narrow point between the Lower and Upper Mystic Lakes, with its west end in Arlington and its east end in Medford. The water system it was a part of eventually merged into the Metropolitan District Commission (MDC), predecessor to the

Massachusetts Water Resources Authority The Massachusetts Water Resources Authority (MWRA) is a public authority in the Commonwealth of Massachusetts that provides wholesale drinking water and sewage services to certain municipalities and industrial users in the state, primarily in th ...

(MWRA) and the

Massachusetts 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 ...

(DCR). As built, the dam was over long and high, with most of that length (about ) consisting of earthen embankments lined with

riprap Riprap (in North American English), also known as rip rap, rip-rap, shot rock, rock armour (in British English) or rubble, is human-placed rock or other material used to protect shoreline structures against scour and water, wave, or ice erosion. ...

and

puddle clay Puddling is both the material and the process of lining a water body such as a channel or pond with puddle clay (puddle, puddling) – a watertight (low hydraulic conductivity) material based on clay and water mixed to be workable. Puddle clay as ...

. Near its center is a

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

area consisting of a series of square columns constructed of granite blocks and a masonry apron. These columns are grooved on their inner faces to facilitate the installation of stop logs. A wooden walkway with a plank railing ran across the top of the dam. A wooden

fish ladder A fish ladder, also known as a fishway, fish pass, fish steps, or fish cannon is a structure on or around artificial and natural barriers (such as dams, locks and waterfalls) to facilitate diadromous fishes' natural migration as well as movemen ...

was built, but removed at a later date. A gatehouse on the Medford side was used to connect the upper lake to a brick-lined aqueduct that delivered the water to Charlestown. The lake area impounded by the dam is . The dam and gatehouse were each listed on the

National Register of Historic Places The National Register of Historic Places (NRHP) is the United States federal government's official list of districts, sites, buildings, structures and objects deemed worthy of preservation for their historical significance or "great artistic v ...

in 1990. By the early 2000s, the dam was known to not be in very good condition, with failing spillway masonry, erosion, and other damage to the dam's stonework. A major storm in 2006 flooded portions of the surrounding area, and highlighted the potential inability of the dam to handle a significant high-water event, leading to catastrophic flooding of downstream areas. Between 2010 and 2012 major work was undertaken to improve the dam's condition. A new spillway was constructed to the east of the old spillway, which received a new spillway apron. Work was done on the embankments and the shores near the upper areas of the dam, and a new fish ladder and bridge were built. The historic gatehouse was also rehabilitated, and modern controls were added, enabling improved control over the water levels behind the dam. Image:WinchesterMA MysticDamAfter2010Modernization.jpg, After the 2010 renovations. Image:WinchesterMA MysticGatehouse.jpg, The gatehouse.

References

{{National Register of Historic Places in Massachusetts Arlington, Massachusetts Dams on the National Register of Historic Places in Massachusetts Buildings and structures in Medford, Massachusetts Dams completed in 1864 Infrastructure completed in 1862 Gatehouses (waterworks) Water supply infrastructure on the National Register of Historic Places National Register of Historic Places in Arlington, Massachusetts National Register of Historic Places in Middlesex County, Massachusetts 1862 establishments in Massachusetts Dams in Massachusetts Dams with fish ladders

See also

References