Flat Rock Reservoir Report
Last Updated: December 18, 2025
Flat Rock is a captivating hydroelectric dam located on the East Branch Oswegatchie River in St.
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Summary
Lawrence, New York. Constructed in 1925, this concrete structure stands at a height of 67 feet and has a hydraulic height of 72 feet, providing a storage capacity of 3382 acre-feet. With a spillway width of 229 feet and a maximum discharge of 12000 cubic feet per second, Flat Rock ensures efficient water management in its surrounding area.
Managed by the Federal Energy Regulatory Commission, Flat Rock is a vital piece of infrastructure for the region, offering renewable energy generation and flood control capabilities. Despite its high hazard potential, the dam is regularly inspected to ensure its structural integrity and safe operation. Additionally, the dam has an emergency action plan in place, meeting established guidelines to mitigate risks and manage potential emergencies effectively. Overall, Flat Rock serves as a key player in water resource management and climate resilience efforts in the area.
With its historical significance and modern functionality, Flat Rock exemplifies the intersection of traditional dam engineering and contemporary hydroelectric technology. As a critical component of the local water infrastructure, this dam plays a crucial role in supporting the region's energy needs and environmental sustainability goals. As water resource and climate enthusiasts, we appreciate the importance of structures like Flat Rock in harnessing the power of water for both human benefit and ecological harmony.
Year Completed |
1925 |
Dam Length |
568 |
Dam Height |
67 |
River Or Stream |
East Branch Oswegatchie River |
Primary Dam Type |
Concrete |
Surface Area |
228 |
Hydraulic Height |
72 |
Drainage Area |
262 |
Nid Storage |
3382 |
Structural Height |
70 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
High |
Foundations |
Rock |
Nid Height |
72 |
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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Oswegatchie 45
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Oswegatchie 44
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Oswegatchie 43
|
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Oswegatchie 42
|
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Oswegatchie 41/High Rock
|
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Cranberry Lake 41
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Flat Rock