Johnsonville Reservoir Report
Nearby: James Thompson Schaghticoke
Last Updated: December 14, 2025
Johnsonville is a private hydroelectric dam located in Rensselaer, New York, along the Hoosic River.
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Summary
Constructed in 1909, this concrete gravity dam stands at 39 feet high and spans 529 feet in length, with a storage capacity of 6430 acre-feet. The dam has a spillway width of 526 feet and can discharge up to 11000 cubic feet per second, making it a crucial infrastructure for water resource management in the area.
Managed by the Federal Energy Regulatory Commission, Johnsonville has a high hazard potential due to its size and location. The dam is inspected regularly by the same agency to ensure its safety and functionality. Despite its age, Johnsonville remains a significant player in the local water resource system, contributing to both hydroelectric power generation and water storage for the surrounding area. As climate change continues to impact water resources, the proper maintenance and monitoring of dams like Johnsonville are essential for sustainable water management practices.
With its historical significance and role in modern water resource management, Johnsonville serves as a reminder of the importance of hydroelectric infrastructure in the face of changing climate conditions. As the dam continues to play a vital role in the region's water management strategies, it stands as a testament to the enduring impact of human engineering on the natural environment. For water resource and climate enthusiasts, Johnsonville offers a fascinating case study in the intersection of technology, sustainability, and environmental stewardship.
Year Completed |
1909 |
Dam Length |
529 |
Dam Height |
39 |
River Or Stream |
Hoosic River |
Primary Dam Type |
Concrete |
Surface Area |
450 |
Drainage Area |
604 |
Nid Storage |
6430 |
Outlet Gates |
Slide (sluice gate) - 4 |
Hazard Potential |
High |
Foundations |
Rock |
Nid Height |
39 |
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.
Johnsonville