Cowanesque Dam Reservoir Report

Last Updated: December 8, 2025

Cowanesque Dam, also known as Cowanesque Lake, is a rockfill dam located on the Cowanesque River in Lawrenceville, Pennsylvania.


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Summary

Completed in 1980 by the US Army Corps of Engineers, the primary purpose of the dam is flood risk reduction, with additional benefits for recreation and water supply. Standing at a height of 151 feet and a length of 3100 feet, the dam has a storage capacity of 84,747 acre-feet and a surface area of 1050 acres.

While Cowanesque Dam helps reduce the risk of flooding to downstream communities, there are still potential hazards that could lead to significant flooding events. The dam has a high hazard potential, with scenarios including high-volume releases from the spillway during storms and rare breaches that could result in uncontrolled surges of water. The U.S. Army Corps of Engineers actively manages and monitors the dam to mitigate risks, conducting regular inspections, updating emergency action plans, and collaborating with local authorities for emergency response exercises.

In the event of a breach or high water event, downstream communities such as Lawrenceville, Tioga, Corning, and Elmira could be impacted by swift and deep floodwaters. It is crucial for residents in these areas to stay informed about the dam's condition and follow emergency protocols. Despite the risks, the proactive risk management measures implemented by the USACE aim to ensure the safety and integrity of Cowanesque Dam and protect surrounding communities from potential flooding disasters.

Year Completed

1980

Dam Length

3100

Dam Height

151

River Or Stream

COWANESQUE RIVER

Primary Dam Type

Rockfill

Surface Area

1050

Hydraulic Height

147.3

Drainage Area

298

Nid Storage

84747

Structural Height

151

Hazard Potential

High

Foundations

Soil

Nid Height

151
       
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.