John C Youngman Reservoir Report

Last Updated: December 9, 2025

John C Youngman, also known as Mosquito Creek Reservoir, is a vital water supply infrastructure in Limestone Township, Pennsylvania.



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Summary

Owned and regulated by the local government, this earth dam stands tall at a height of 100.5 feet and was completed in 1951. With a storage capacity of 2581 acre-feet, it serves the primary purpose of water supply for the surrounding area.

Situated along the Mosquito Creek in Lycoming County, Pennsylvania, the John C Youngman dam plays a crucial role in managing water resources in the region. Despite its fair condition assessment and high hazard potential, the dam has been inspected regularly, with the last inspection conducted in October 2020. The Pennsylvania Department of Environmental Protection oversees its permitting, inspection, and enforcement, ensuring its safety and reliability for water supply.

Climate and water resource enthusiasts will be intrigued by the engineering and environmental aspects of the John C Youngman dam, as well as its impact on the local ecosystem. With a surface area of 61 acres and a drainage area of 2.12 square miles, this dam not only provides water storage but also contributes to flood control and water quality management along the Mosquito Creek. Its historical significance and ongoing maintenance efforts make it a noteworthy site for those interested in sustainable water resource management and climate resilience.

Year Completed

1951

Dam Length

600

Dam Height

100.5

River Or Stream

MOSQUITO CREEK

Primary Dam Type

Earth

Surface Area

61

Drainage Area

2.12

Nid Storage

2581

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

101
       
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.