US Army Corps of Engineers
New York District

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

Flood Risk Management Project

Published Sept. 1, 2018

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:  Section 401(a) of WRDA 1986

STATUS: A Design Agreement was signed by the District and NYS Department of Conservation (NYSDEC) and Westchester County for the GRR Study and Pre 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 Plan (NED) at a total construction cost of $82,250,000 (FY 2018 price level).  The final Chief of Engineer’s Report was signed and the report has been submitted to the Assistant Secretary of the Army, upon approval the report will be sent to OMB and on to Congress for consideration in an authorization bill.  Remaining 2007 Supplemental Funds total approximately $535,000 of $700,000 needed for the Federal portion of PED of the first constructible element.  These funds will be used upon the approval to move into PED and/or a construction authorization.


Mr. Matthew Cosby, PMP

Phone: (917) 790-8080, Fax: (212) 264-2924


Programs and Project Management, Civil Works Branch

26 Federal Plaza, New York, NY 10278-0090