Tomhannock Reservoir Dam Reservoir Report

Last Updated: December 15, 2025

The Tomhannock Reservoir Dam, located in Rensselaer, New York, serves as a critical water supply infrastructure for the local communities of Pittstown and Schaghticoke.


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Summary

Completed in 1905, this earth dam stands at a height of 68 feet and has a length of 700 feet, with a maximum storage capacity of 56,600 acre-feet. The reservoir covers a surface area of 1,742 acres and has a normal storage level of 39,521 acre-feet, providing essential water resources for the region.

Managed by the local government and regulated by the New York State Department of Environmental Conservation, the Tomhannock Reservoir Dam has been assessed as being in satisfactory condition with a high hazard potential. Its spillway, with a width of 300 feet, is uncontrolled, and the dam is inspected every two years to ensure its structural integrity. While the dam poses a moderate risk, measures are in place to manage and mitigate any potential hazards, ensuring the safety and security of the surrounding communities.

For water resource and climate enthusiasts, the Tomhannock Reservoir Dam represents a crucial piece of infrastructure that supports the local water supply needs and contributes to the overall environmental resilience of the area. With its historical significance and ongoing maintenance efforts, this dam serves as a testament to the importance of sustainable water management practices in the face of changing climate conditions and increasing water demands.

Year Completed

1905

Dam Length

700

Dam Height

68

River Or Stream

TOMHANNOCK CREEK

Primary Dam Type

Earth

Surface Area

1742

Drainage Area

66.6

Nid Storage

56600

Hazard Potential

High

Nid Height

68
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.