Hannawa Reservoir Report
Nearby: Sugar Island Potsdam - West Dam
Last Updated: December 18, 2025
Hannawa Dam, located in Potsdam, New York, is a privately owned structure on the Raquette River that serves multiple purposes, including hydroelectric power generation, fire protection, and creating a small fish pond.
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Summary
Built in 1902, this gravity dam stands at 34 feet tall and has a length of 255 feet, with a storage capacity of 690 acre-feet. The dam's uncontrolled spillway has a width of 216 feet and a maximum discharge of 12,700 cubic feet per second.
Managed by the Federal Energy Regulatory Commission, Hannawa Dam is inspected regularly to ensure its structural integrity and low hazard potential. Despite being considered a moderate risk structure, the dam has not had any recent condition assessments available. While the dam does not fall under state regulation or permitting, it is subject to federal oversight and enforcement. The surrounding area has a drainage area of 993 square miles and a surface area of 204 acres, making it an important water resource in the region.
Overall, Hannawa Dam is a key component in managing water resources and providing hydroelectric power in St. Lawrence County, New York. Its historical significance and multi-purpose design make it a valuable asset for the community while also highlighting the importance of infrastructure maintenance and risk management in the face of changing climate conditions. This dam serves as a reminder of the delicate balance between harnessing nature for human benefit and ensuring the safety and sustainability of our water resources for future generations.
Year Completed |
1902 |
Dam Length |
255 |
Dam Height |
34 |
River Or Stream |
Raquette River |
Primary Dam Type |
Gravity |
Surface Area |
204 |
Drainage Area |
993 |
Nid Storage |
690 |
Outlet Gates |
Slide (sluice gate) - 1, Tainter (radial) - 1 |
Hazard Potential |
Low |
Foundations |
Rock |
Nid Height |
34 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Raquette River At South Colton Ny
|
360cfs |
W Br St. Regis R Nr Parishville Ny
|
211cfs |
Raquette River At Raymondville Ny
|
2060cfs |
Grass River At Chase Mills Ny
|
1350cfs |
St. Regis River At Brasher Center Ny
|
534cfs |
Oswegatchie River Near Heuvelton Ny
|
1250cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Hannawa