Stillwater Dam Reservoir Report

Last Updated: December 6, 2025

Stillwater Dam, also known as Stillwater Lake, is a federal-owned rockfill dam located in Forest City, Pennsylvania.


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Summary

Completed in 1960, the dam serves primarily for flood risk reduction, but also supports recreation and water supply purposes. With a height of 77 feet and a capacity of 17,000 acre-feet, the dam controls the flow of the Lackawanna River, reducing the risk of downstream flooding. However, despite its risk reduction measures, the dam still poses a high hazard potential, especially in scenarios involving high-volume releases from the spillway during significant storm events or rare breaches that could lead to devastating flooding in communities along the river.

The U.S. Army Corps of Engineers (USACE) plays a crucial role in managing and reducing the risks associated with Stillwater Dam. With ongoing maintenance, inspections, and monitoring, the integrity of the dam is ensured, and emergency preparedness measures are in place. USACE regularly updates the Emergency Action Plan for the dam, conducts emergency response exercises with relevant authorities, and closely monitors weather forecasts to provide timely flood warnings. Despite these efforts, the downstream communities, including Forest City, Carbondale, and Scranton, remain at risk, emphasizing the importance of continued vigilance and preparedness in the face of potential flood events stemming from the dam.

Year Completed

1960

Dam Length

1700

Dam Height

77

River Or Stream

LACKAWANNA RIVER

Primary Dam Type

Rockfill

Surface Area

422

Hydraulic Height

72.1

Drainage Area

37

Nid Storage

17000

Structural Height

77

Hazard Potential

High

Foundations

Soil

Nid Height

77
       
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.