Thorn Hill Park Detention Basin Reservoir Report

Last Updated: December 6, 2025

Thorn Hill Park Detention Basin in Marshall Township, Allegheny County, Pennsylvania, is a vital piece of infrastructure designed for flood risk reduction along the TR Brush Creek.


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Summary

Completed in 1987, this earth dam stands at a height of 18 feet and spans 1,125 feet in length, providing a storage capacity of 28.9 acre-feet to help manage stormwater runoff in the area. The primary purpose of this detention basin is to safeguard the surrounding communities from potential flooding events, with the Pennsylvania Department of Environmental Protection overseeing its state-regulated operations.

Despite its significant hazard potential, Thorn Hill Park Detention Basin has been rated as being in fair condition during its last assessment in September 2017. The dam is subject to regular inspection every two years to ensure its structural integrity and effectiveness in flood risk reduction. The basin's emergency action plan status and risk management measures remain unspecified in the available data, though its location, design, and capacity underscore its importance in mitigating flood-related risks in the region. As climate change continues to impact weather patterns, structures like Thorn Hill Park Detention Basin play a crucial role in enhancing community resilience to extreme weather events.

Year Completed

1987

Dam Length

1125

Dam Height

18

River Or Stream

TR BRUSH CREEK

Primary Dam Type

Earth

Drainage Area

0.2

Nid Storage

28.9

Hazard Potential

Significant

Foundations

Unlisted/Unknown

Nid Height

18
       
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.