Swan Lake Dam Reservoir Report

Last Updated: December 6, 2025

Swan Lake Dam, located in Sullivan County, New York, was completed in 1894 and serves as a vital water resource for the area.


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Summary

With a primary purpose of recreation, this stone dam stands at a height of 31 feet and has a length of 135 feet, creating a reservoir with a storage capacity of 3,760 acre-feet. The dam is situated on the West Branch Mongaup River and is regulated by the New York State Department of Environmental Conservation.

Despite its age, Swan Lake Dam is in fair condition according to a 2013 assessment, with a significant hazard potential due to its location and structural characteristics. The dam is regularly inspected every four years, with the last inspection conducted in December 2018. The risk assessment for the dam indicates a very high risk level, emphasizing the importance of ongoing monitoring and maintenance to ensure the safety and stability of the structure.

Managed by a private owner, Swan Lake Dam plays a crucial role in providing recreational opportunities and water storage for the region. With its controlled spillway and significant storage capacity, the dam is a key feature in the local water infrastructure. As climate change impacts continue to affect water resources, the maintenance and safety of dams like Swan Lake Dam will be essential in safeguarding against potential risks and ensuring sustainable water management for the future.

Year Completed

1894

Dam Length

135

Dam Height

31

River Or Stream

WEST BRANCH MONGAUP RIVER

Primary Dam Type

Stone

Surface Area

327

Drainage Area

14.54

Nid Storage

3760

Hazard Potential

Significant

Nid Height

31
       
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.
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Area Campgrounds