Loch Lyall Dam Reservoir Report

Last Updated: December 5, 2025

Loch Lyall Dam, located in Nelson Corners, Putnam, New York, is a concrete dam completed in 1950 primarily for recreational purposes.


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Summary

Standing at a height of 11 feet and spanning 400 feet in length, the dam boasts a storage capacity of 98 acre-feet, with a normal storage level of 60 acre-feet. The dam impounds Indian Brook, offering a surface area of 19 acres for recreational activities such as boating and fishing.

Despite its recreational appeal, Loch Lyall Dam presents significant hazard potential with a poor condition assessment. Inspected in November 2020, the dam's maintenance and emergency preparedness are key concerns. With a moderate risk rating, there is a need for ongoing risk management measures to ensure the safety and integrity of the structure. The dam is regulated by the New York State Department of Environmental Conservation, which conducts regular inspections, permits, and enforcement to uphold safety standards.

Enthusiasts of water resources and climate will find Loch Lyall Dam a fascinating subject for study and monitoring. Its historical significance, design features, and risk profile offer valuable insights into the intersection of recreational infrastructure and environmental stewardship. By staying informed about the dam's condition, regulatory oversight, and risk assessment, enthusiasts can contribute to the preservation and sustainable management of this essential water resource in New York.

Year Completed

1950

Dam Length

400

Dam Height

11

River Or Stream

INDIAN BROOK

Primary Dam Type

Concrete

Surface Area

19

Nid Storage

98

Hazard Potential

Significant

Nid Height

11
       
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.