Middle Branch Dam and Reservoir

Location:  Croton Watershed


Architect/Engineer/Other Responsible Parties:  Croton Aqueduct Department, reorganized as the Department of Public Works in 1870, William “Boss” Tweed, Commissioner

Historic Use:  Dam and reservoir for the Croton System 

Present Use:  Same

Typology:  Dam/Reservoir

Period(s) of Construction:  1866-1873 

Date of Decommissioning:    N/A

Date(s) of Demolition:  N/A

Structural System/Materials:  Masonry dam, 670 feet long, 57 feet high; “rusticated stone ashlars facing both the vertical upstream face and the battered downstream side of the dam.  The heart, or ‘hearting,’ of the dam was composed of large undressed stones set in concrete.  A small stone gatehouse was located at the base of the downstream face, and the overflow was designed to spill down a wasteway cut from the natural bedrock.” (Water-works) 

Significant Alterations:  Buttressed by earthworks shortly after construction, although this addition did more harm than good, and was eventually removed; 1990, as part of large modernization of 19 reservoirs in city system.


“Immediately after the completion of Boyd’s Corners Dam, officials from the new Department of Public Works questioned the strength of its masonry wall and the overall soundness of the design.  The new department ordered an earthen embankment to be built against the upstream side, ostensibly to strengthen the structure by resisting some of the lateral pressure of the impounded water.  But it seems the huge and unnecessary embankment project was just another opportunity for graft, and the work, like much of the construction during the Tweed era, was poorly done with little regard for the requirements or specifications of the project.  The engineer originally responsible for the construction of the dam observed that the earth embankment was badly built of improperly compacted and porous materials.  It was soon fully saturated, and probably did more to increase pressure on the structure than reduce it” (Water-works, 66).


Kevin Bone, “The Extension of the Croton System,”  Water-works:  The Architecture and Engineering of the New York City Water Supply, Kevin Bone, ed. (New York:  The Irwin S. Chanin School of Architecture of the Cooper Union and The Monacelli Press, 2006)

NYC.gov website. “Boyds Corners.”  http://www.nyc.gov/html/dep/html/watershed_protection/boyds_corners.shtml


Jørgen G. Cleemann


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