Onondaga Dam Reservoir Report

Last Updated: December 6, 2025

Onondaga Dam, located in Onondaga Nation, New York, was completed in 1949 with the primary purpose of flood risk reduction along the Onondaga Creek.


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Summary

As a state-regulated dam with a height of 67 feet and a length of 2050 feet, it provides storage capacity of 48,400 acre-feet and has a maximum discharge capacity of 82,350 cubic feet per second. The dam has a surface area of 2500 acres and a drainage area of 68.1 square miles, making it a crucial structure for managing water resources in the region.

Despite its high hazard potential, the dam is in satisfactory condition, according to a 2017 assessment. The dam's emergency action plan is up to date, with regular inspections conducted every two years to ensure its integrity and safety. The spillway type for the dam is uncontrolled, with a width of 200 feet, further enhancing its ability to manage floodwaters effectively. With moderate risk assessment and enforcement by the New York State Department of Environmental Conservation, Onondaga Dam plays a vital role in safeguarding the surrounding area from potential flooding events and highlights the importance of proper water resource management in the face of changing climate conditions.

Year Completed

1949

Dam Length

2050

Dam Height

67

River Or Stream

ONONDAGA CREEK

Primary Dam Type

Earth

Surface Area

2500

Drainage Area

68.1

Nid Storage

48400

Hazard Potential

High

Nid Height

67
       
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.