Hemlock Lake Dam Reservoir Report

Last Updated: December 6, 2025

Hemlock Lake Dam, located in Hartwood Club, Sullivan County, New York, is a privately owned structure primarily used for recreation.


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Summary

This earth dam, standing at a height of 27 feet and stretching 200 feet in length, was completed in 1890 and has a storage capacity of 536 acre-feet. The dam overlooks the Bush Kill river and has a controlled spillway with a width of 19 feet, showcasing engineering excellence from the late 19th century.

With a significant hazard potential and a very high risk assessment rating, Hemlock Lake Dam is under state regulation and inspection by the New York State Department of Environmental Conservation. While the dam's condition is currently not rated, its emergency action plan status and risk management measures are not specified. Despite its age, the dam continues to serve its recreational purpose, providing a serene backdrop for water resource and climate enthusiasts to appreciate and study.

As a historical landmark with a rich engineering heritage, Hemlock Lake Dam stands as a testament to early dam construction in New York State. Its picturesque setting and controlled spillway design make it a popular destination for outdoor enthusiasts and researchers alike. While its risk potential is noted, ongoing state oversight ensures the safety and integrity of this important water resource infrastructure for future generations to enjoy and learn from.

Year Completed

1890

Dam Length

200

Dam Height

27

River Or Stream

BUSH KILL

Primary Dam Type

Earth

Surface Area

38

Nid Storage

536

Hazard Potential

Significant

Nid Height

27
       
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.