Downsville Dam Reservoir Report

Last Updated: December 6, 2025

Downsville Dam, also known as Pepacton Reservoir, is located in Downsville, Delaware, New York, along the East Branch Delaware River.


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Summary

Completed in 1954, this earth dam stands at a height of 204 feet and stretches 2400 feet in length. Its primary purpose is water supply, with a maximum storage capacity of 609,740 acre-feet and a normal storage capacity of 420,280 acre-feet. The dam's surface area covers 5763 acres, serving a drainage area of 372 square miles.

Managed by local government authorities and regulated by the New York State Department of Environmental Conservation, Downsville Dam poses a high hazard potential, yet its condition assessment remains satisfactory as of February 2020. The dam is equipped with an uncontrolled spillway measuring 800 feet in width, capable of handling a maximum discharge of 200,000 cubic feet per second. Despite its moderate risk rating, the dam has undergone regular inspections, with the next scheduled assessment set for 2022. Overall, Downsville Dam stands as a critical water resource infrastructure supporting the region's water supply needs while ensuring safety and regulatory compliance.

Year Completed

1954

Dam Length

2400

Dam Height

204

River Or Stream

EAST BRANCH DELAWARE RIVER

Primary Dam Type

Earth

Surface Area

5763

Drainage Area

372

Nid Storage

609740

Hazard Potential

High

Nid Height

204
       
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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.