Unionville Reservoir Report
Nearby: Hewittville Sissonville
Last Updated: December 18, 2025
Unionville is a private hydroelectric dam located on the Raquette River in St.
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Summary
Lawrence, New York. Built in 1907, this concrete dam stands at a height of 20 feet and spans 350 feet in length, with a storage capacity of 99 acre-feet. The dam serves multiple purposes, including fire protection, stockpond, and recreation, in addition to generating hydroelectric power.
Managed by the Federal Energy Regulatory Commission, Unionville is regulated by the New York State Department of Environmental Conservation. With a low hazard potential and moderate risk assessment, the dam features an uncontrolled spillway with a width of 300 feet. The dam's condition assessment is currently unavailable, but it undergoes inspections every three years to ensure its structural integrity and safety measures. Unionville offers a glimpse into the intersection of water resource management and climate considerations, highlighting the importance of balancing energy production with environmental preservation in our changing climate landscape.
Year Completed |
1907 |
Dam Length |
350 |
Dam Height |
20 |
River Or Stream |
Raquette River |
Primary Dam Type |
Concrete |
Surface Area |
35 |
Drainage Area |
1036 |
Nid Storage |
99 |
Outlet Gates |
Slide (sluice gate) - 2 |
Hazard Potential |
Low |
Foundations |
Rock |
Nid Height |
20 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Raquette River At Raymondville Ny
|
2010cfs |
Grass River At Chase Mills Ny
|
1350cfs |
St. Regis River At Brasher Center Ny
|
588cfs |
Raquette River At South Colton Ny
|
360cfs |
W Br St. Regis R Nr Parishville Ny
|
211cfs |
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.
Unionville