Lake Oniad Dam Reservoir Report

Last Updated: December 6, 2025

Lake Oniad Dam, located in Wappingers Falls, New York, is a private recreational dam on the TR-Wappinger Creek.


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Summary

The dam, primarily made of concrete, stands at 8 feet in height and stretches 20 feet in length, with a storage capacity of 59 acre-feet. With a spillway width of 18 feet and an uncontrolled spillway type, the dam has a low hazard potential and is classified as having a moderate risk level.

Owned privately, the dam is regulated by the New York State Department of Environmental Conservation (NYS DEC) and is subject to state permitting, inspection, and enforcement. Despite its low hazard potential, the dam has not been rated for its condition assessment. The last inspection of Lake Oniad Dam was conducted in March 2013, with a risk assessment indicating a moderate risk level.

Overall, Lake Oniad Dam serves as a key recreational structure in Dutchess County, New York, offering opportunities for water activities and enjoyment for visitors. Its location and design make it a significant asset for the community, albeit with necessary oversight and maintenance to ensure its safety and functionality for years to come.

Dam Length

20

Dam Height

8

River Or Stream

TR-WAPPINGER CREEK

Primary Dam Type

Concrete

Surface Area

13

Nid Storage

59

Hazard Potential

Low

Nid Height

8
       
Seasonal Comparison

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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.