Hannibal Dam Reservoir Report

Last Updated: December 6, 2025

Located in Oswego, New York, the Hannibal Dam stands as a crucial structure for fire protection, stocking, and small fish pond purposes since its completion in 1907.


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Summary

With a height of 10 feet and a length of 110 feet, this concrete dam on Ninemile Creek has a storage capacity of 10 acre-feet and serves as a recreational spot for enthusiasts in the area.

Managed by local government authorities and regulated by the New York State Department of Environmental Conservation, the Hannibal Dam is categorized as having a significant hazard potential with a fair condition assessment as of June 2017. The dam features an uncontrolled spillway with a width of 34 feet and a drainage area of 22 square miles, contributing to its moderate risk assessment level.

Visitors can appreciate the historical significance and functionality of the Hannibal Dam while also recognizing the importance of its role in water resource management and climate resilience efforts. As a key element in the region's infrastructure, the dam continues to play a vital role in safeguarding the community against potential hazards while offering opportunities for recreation and environmental stewardship along Ninemile Creek.

Year Completed

1907

Dam Length

110

Dam Height

10

River Or Stream

NINEMILE CREEK

Primary Dam Type

Concrete

Surface Area

3

Drainage Area

22

Nid Storage

10

Hazard Potential

Significant

Nid Height

10
       
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.