Wilmington Dam Reservoir Report

Last Updated: December 20, 2025

The Wilmington Dam, located in Wilmington, New York, serves as a crucial structure on the WEST BRANCH AUSABLE RIVER, offering recreational opportunities and other purposes for the local community.


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Summary

Built-in 1937, this concrete dam stands at a height of 16 feet and spans 255 feet in length. With a storage capacity of 250 acre-feet and a drainage area of 142 square miles, the dam plays a significant role in managing water resources in the region.

Managed by the local government and regulated by the NYS DEC, the Wilmington Dam has a spillway width of 228 feet and a maximum discharge capacity of 16,130 cubic feet per second. Despite being classified as having a "Significant" hazard potential, the dam's condition is currently "Not Rated", with inspections conducted every 4 years. The risk assessment for the dam is moderate, indicating the need for ongoing monitoring and management measures to ensure its safety and functionality for the surrounding area's water resources and climate resilience.

As an essential infrastructure asset in Essex County, New York, the Wilmington Dam stands as a testament to engineering ingenuity and the importance of water management in the face of changing climate patterns. With its historical significance and continued role in water resource management, the dam serves as a focal point for local stakeholders and climate enthusiasts alike, highlighting the intersection of infrastructure, water resources, and climate resilience in the region.

Year Completed

1937

Dam Length

255

Dam Height

16

River Or Stream

WEST BRANCH AUSABLE RIVER

Primary Dam Type

Concrete

Surface Area

26

Drainage Area

142

Nid Storage

250

Hazard Potential

Significant

Nid Height

16
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.