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FACT SHEET - Mamaroneck & Sheldrake Rivers, Village of Mamaroneck, NY

Flood Risk Management Project

U.S. Army Corps of Engineers, New York District
Published Jan. 4, 2024

DESCRIPTION:  A severe flood risk persists in the Village of Mamaroneck, NY along the Mamaroneck River and Sheldrake River based on the recurrence of flood events and the damages sustained.  The largest floods of record resulted from the storms of October 1955, June 1972, September 1975, and April 2007.  Extensive damages and loss of life have occurred during these major flood events.  Damages within the Mamaroneck and Sheldrake Rivers Basin for the June 1972 and September 1975 floods alone amounted to approximately $18M and $92M, respectively, based on conditions of development at the time and October 2015 price levels.  A combination of low channel capacity, small bridge openings, developmental encroachment along both rivers, urbanization, and a poor flow conveyance at the confluence of both rivers has contributed to significant and frequent flooding.  

A Chief of Engineer’s Report was signed on 14 Dec 2017 this General Reevaluation Report (GRR) was being conducted after interest peaked following storm events in 2007, which struck the Mamaroneck and Sheldrake Basin flooding homes and businesses.  This GRR was an attempt at resolving issues with previous studies that yielded a 1977 Feasibility Report and a 1989 General Design Memorandum (1989 GDM) which did not proceed to construction due to concerns of the non-Federal sponsors relating to the costs and separable element justification.  

AUTHORIZATION:   Authorized for construction in Section 1401 of the American Water Infrastructure Act of 2018 (Public Law 115-279).

STATUS:  A Design Agreement was signed by the District and NYS Department of Conservation (NYSDEC) and Westchester County for the GRR Study and Preconstruction Engineering and Design (PED) on 1 Mar 2010. A Chief of Engineer’s Report was signed on 14 Dec 2017 which finalized the GRR study. The Chief of Engineer’s Report proposed a National Economic Development (NED) plan at a total first construction cost of $88,057,000 (FY 2021 price level).  The final Chief of Engineer’s Report was signed, and the report has been submitted to the Assistant Secretary of the Army. The report was sent to OMB and Congress for consideration in an authorization bill. The project was authorized for construction by Congress as noted above in 2018.  The Federal and Non-Federal portion of PED funding of the first constructible element has proceeded with coordination with the Village of Mamaroneck.  The PED effort has been completed for the preparation of the first set of plans and specifications of the first construction contract, the demolition of the Ward Avenue bridge deck. A Project Partnership Agreement (PPA) is anticipated to be signed with NYSDEC for the remainder of the project, anticipated for Summer 2024. The project construction was funded in the Disaster Relief Supplemental Appropriations Act or Public Law 117–43 on 30 September 2021. 


Ms. Bethany McClanahan P.E., CFM

Phone: (917) 790-8426

E-mail: Bethany.M.McClanahan@usace.army.mil

Programs and Project Management, Civil Works Branch

26 Federal Plaza, New York, NY 10278-0090