More and more, extraordinary weather events are becoming the norm in Westchester County. Nor’easters, tropical storms and thunderstorms have deluged Westchester, often with greater frequency and intensity. Some recent and memorable weather events were the late winter/spring 2007 storms, especially an April nor’easter that dumped up to nine inches of rain on southern Westchester just as residents and business owners were recovering from a large storm only weeks earlier. In late summer of 2011, Hurricane Irene and Tropical Storm Lee hit the region within 10 days of each other, dropping a total of nearly 11 inches of rain. Superstorm Sandy, in October of 2012, while not resulting in significant rainfall still caused extreme coastal flooding from storm surge and high winds. Chronic flooding from short-lived but intense thunderstorms throughout the county wreaks havoc with some neighborhoods, where roads become impassable, stormwater enters homes, and lawns become ponds.
To lessen the risks associated with flooding on residents and businesses, the county is leading several efforts to better understand ways in which flooding can be controlled, to educate the public and municipal officials about flooding and flood mitigation, and to implement projects that will lessen the degree of flooding. The county also has partnered with other governmental entities to leverage its efforts.
The Army Corps of Engineers re-studied flooding along the Saw Mill River in Greenburgh and Elmsford that led to its 2002 “Project Management Plan (PMP) for the Saw Mill River at Elmsford and Greenburgh, New York.” Read the report.
The Army Corps of Engineers is also re-studying flooding in the Village of Mamaroneck and revising prior plans for a diversion tunnel to include a wide variety of cost effective measures to reduce flooding throughout the village.
Stormwater Management Law - Stormwater Reconnaissance Plans
The county enacted a Stormwater Management Law in 2011 requiring the county to develop “reconnaissance” plans that assess current conditions and identify cost-effective projects to directly address flooding and flood damage and impacts in Westchester. County projects to lessen the risks and impacts associated with flooding will be guided by these plans. A Stormwater Advisory Board created under the law began meeting in 2012, and is advising the county on flood-related matters, including the development of the reconnaissance plans and on projects to better manage stormwater.
Under Stormwater Management Law, the County Department of Planning is charged with developing flood-related stormwater “reconnaissance plans” for each of the county’s major watersheds or drainage basins. Working with the municipalities in each of these watersheds as well as the County’s Department of Public Works and Transportation, Planning has completed:
(1) Stormwater Reconnaissance Plan for the Saw Mill River-Pocantico River Watershed (December 2012), and
(2) Stormwater Reconnaissance Plan for the Bronx River Watershed (April 2013).
(3) Stormwater Reconnaissance Plan for the Coastal Long Island Sound Watershed (August 2013).
Planning is currently developing a plan for the Haverstraw and Peekskill bays watershed portion of the Hudson River watershed in Westchester. The three completed reconnaissance plans are currently being reviewed by the county Board of Legislators.
The county has been incorporating stormwater management into its infrastructure and building improvement projects, where applicable, including practices to detain and absorb stormwater runoff. Examples include improvements to sections of the Bronx River Parkway and parking lot reconstruction at the Westchester County Center. It also has partnered with other governmental entities to leverage its efforts, largely through grants, to install stormwater practices at other county and municipal facilities. View completed stormwater management and natural resources restoration projects.
PowerPoint presentations on these county initiatives to address flooding are titled, “Flooding in Westchester: Addressing Local and Regional Impacts” and “Westchester County Stormwater Management Law.”
The county also has developed a manual for elected officials, planning and zoning board members, planners and development professionals to improve land use decisions with respect to flooding and flood damage. The manual, titled “Flooding and Land Use Planning: A Guidance Document for Municipal Officials and Planners,” covers topics such as flooding causes, the relationship to development, regulations and site plan review tools. It includes an extensive appendix of additional information and resources. View the manual.
Flood Zone Mapping
The Federal Emergency Management Agency (FEMA) updated the Flood Insurance Rate Maps for Westchester. To find out if your property is in a designated flood zone, go to the county’s interactive maps. Enter your address and click "Go." Select the "Show Additional Data on Map" tab at lower right, click the "plus" sign in front of “Environmental Features” and then check the check box in front of "Floodplains."