Twin Lakes No 1 Reservoir Report

Last Updated: December 5, 2025

Twin Lakes No 1, located in Westmoreland, Pennsylvania, is a recreational earth dam completed in 1908 with a height of 31 feet and a storage capacity of 470 acre-feet.


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Summary

Managed by the Pennsylvania Department of Environmental Protection, the dam sits on Little Crabtree Creek and serves as a vital water resource for the surrounding community. With a surface area of 33 acres and a drainage area of 1.9 square miles, Twin Lakes No 1 provides not only recreational opportunities but also essential water storage for the area.

Despite its age, Twin Lakes No 1 remains in satisfactory condition according to its most recent inspection in August 2019, with a high hazard potential due to its location. The dam, primarily used for recreation, offers a peaceful escape for visitors while also serving a crucial role in water management and flood control. As a state-regulated structure, it undergoes regular inspections and maintenance to ensure its continued safety and functionality. With its historical significance and environmental impact, Twin Lakes No 1 stands as a testament to the importance of responsibly managing and preserving our water resources in the face of changing climate patterns.

Year Completed

1908

Dam Length

950

Dam Height

31

River Or Stream

LITTLE CRABTREE CREEK

Primary Dam Type

Earth

Surface Area

33

Drainage Area

1.9

Nid Storage

470

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

31
       
Seasonal Comparison

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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.