Watershed Planning

In Westchester, there are six major drainage basins; Peekskill & Haverstraw Bay, Croton River, Pocantico & Saw Mill River, Inland Long Island Sound, Bronx River, and the Coastal Long Island Sound Watershed. The planning department provides a lead role, including administrative and technical support for watershed planning efforts in the county.

The Department of Planning’s Watershed Planning program endeavors to maintain and provide information and tools to the public and municipalities in accessible forms. Through collaboration with local municipal partners and environmental organizations, we educate the public about stormwater, watersheds, and best management practices for controlling stormwater to prevent pollution and mitigate flooding. These efforts include capital funding for flood mitigation projects, developing and maintaining watershed-wide studies, and providing community science water quality sampling tools. Additionally, the Croton Watershed-based project and septic funding is also managed through this the watershed planning program. Please contact us if you have any specific questions or needs about programs or past/present watershed plans.

Westchester County Watersheds

Westchester County contains a myriad of streams and waterways that provide many benefits to residents including ecological health, recreation, and quality of life. Westchester County has six (6) major watersheds: the Coastal Long Island Sound, the Bronx River, the Saw Mill and Pocantico rivers, the Peekskill and Haverstraw bays, and the Croton River and Inland Long Island Sound. Watersheds are used as a common way to define areas of study when dealing with a wide variety of environmental issues. Each watershed contains subwatersheds and Westchester County has approximately 60! They encompass the land area that drains to a stream, lake or common waterway. The Department of Planning maintains an active watershed planning program, with periodic updates to watershed plans. If you would like more information about your local watershed, visit our Westchester’s Waterways Portal.

New York City Watershed

The largest reservoir system in the county is part of the New York City water supply system which has three components:

• Croton Reservoir Source System, which covers 18,000 acres of land and water surface in Westchester plus additional areas of Putnam County
• Catskill system
• Delaware system

Water from the two upstate systems passes through Westchester via aqueducts and into reservoirs on the way to New York City. New York City’s water supply system provides water to 85% of Westchester’s residents. All the reservoirs that are part of the New York City water supply system that are East of the Hudson River are featured on this map.

Twelve (12) Westchester County municipalities have some land in the New York City watershed: The Towns of Bedford, Cortlandt, Harrison, Lewisboro, Mount Pleasant, New Castle, North Castle, North Salem, Pound Ridge, Somers, Yorktown, and the Village/Town of Mount Kisco. The Map of Croton-Kensico Watershed shows the exact outline of the watershed. One can type in an address to determine if it is located in the watershed.

 Watershed Mapper – Westchester Waterways Portal

Westchester Waterways is our NEW watershed educational tool. Configured for both community members and municipal officials, come explore what encompasses Westchester’s watersheds. Located in this portal, you will also find an anonymous flood reporting tool, where anybody can report a site of a flooding event within their community and also guidance on how to report any flooding instances to your respective legislator as well as guidance to where reports for other observed environmental violations can be sent.

Check out our Westchester’s Waterways portal to find all information related to Watersheds in your community, and also report any flooding instances to alert your municipal officials or your local legislatures!

How to Navigate Mapper:

Experience tabs that cater to different audience types.

• For Community Members: Catered for the Westchester County community members, this section showcases where the different watershed features in Westchester are like streams, flood zones, aquifers, and lakes and ponds are.
• For Municipalities: While geared for municipal officials, anybody can explore this section! Here you will find the different capital programs boundaries for Westchester initiatives as well as the anonymous flood survey report results.
• Flooding Reporting Tool: This anonymous survey will be used to collect flooding reports throughout Westchester County and help inform municipal officials about local flooding reports. The objective with this survey is to help inform the respective officials about flooding in their area to help better prioritize flooding projects in those areas. The objective with this survey is to help inform the respective officials about flooding in their area to help better prioritize flooding projects in those areas.

Watershed Plans and Studies

Early watershed plans were focused on water quality issues, particularly better management of stormwater runoff, as there was much federal funding and regulatory development during the 1980s and 1990s. With increased flooding experienced over the past two decades, watershed plans have switched focus to flood mitigation and community resilience.

Watershed studies have a direct public benefit by supporting existing programs and efforts whereby studies are commissioned, managed, and owned by the County and the findings, models, recommendations and data remain available for public use and implementation. The watershed studies, by identifying flood-prone zones, impaired streams, and vulnerable infrastructure will allow the Department of Planning to direct capital funds toward efficient and effective projects. On the water quality-side, sources of pollution, stormwater runoff, failing septic systems, and other infrastructure pitfalls may be identified to provide a prioritized list for capital investments that improves quality of life county-wide. The following is a recent history of watershed plans within the county. Please contact us if you’re interested in obtaining a digital copy of a plan.

The Environmental Division is undergoing a period of review with regard to its watershed plans. Weather and land use changes within the county necessitate updated plans to develop effective, community-driven strategies to mitigate flooding and flood damage. Much of lower Westchester has been recently studied for flood mitigation by the NYSDEC through the Resilient NY program. Resilient NY studies focus on the main stem of the streams in studied watersheds, potentially missing areas of localized flooding and opportunities for flood mitigation throughout the watershed. The Department of Planning has initiated the process to modernize watershed plans to identify flood problem areas with the latest tools and provide coordinated solutions that achieve county and regional goals. Updates will also include a significant public engagement component in the development of recommended strategies. Proposed plans will provide decision makers and the public critical information to implement efforts that prioritize resilient and sustainable communities, and support the engineering-oriented components of the plans that will result in identification and conceptual in identification, conceptual design and preliminary cost estimates for physical mitigation projects (water quality, flooding and other watershed issues).