Harrisville Reservoir Report
Nearby: Alpina Dam Blanchard Pond Dam
Last Updated: December 22, 2025
Located in Harrisville, New York, the Harrisville Dam is a concrete structure built in 1905 for hydroelectric purposes on the West Branch Oswegatchie River.
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Summary
Managed privately, the dam stands at 25 feet tall and spans 385 feet in length, with a storage capacity of 84 acre-feet. With a low hazard potential and moderate risk assessment, the dam is inspected every three years by the Federal Energy Regulatory Commission to ensure compliance with safety regulations.
The dam features an uncontrolled spillway with a width of 220 feet and two slide gates for water release. While the condition assessment is not available, the dam's risk management measures are in place to mitigate potential hazards. The surrounding area has a drainage area of 198 square miles, making it a critical water resource for the region. With its historical significance and impact on the local ecosystem, the Harrisville Dam remains a key structure for water resource and climate enthusiasts to monitor and study.
Year Completed |
1905 |
Dam Length |
385 |
Dam Height |
25 |
River Or Stream |
West Branch Oswegatchie River |
Primary Dam Type |
Concrete |
Surface Area |
25 |
Drainage Area |
198 |
Nid Storage |
84 |
Outlet Gates |
Slide (sluice gate) - 2 |
Hazard Potential |
Low |
Foundations |
Rock |
Nid Height |
25 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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.
Harrisville