Glen Elyn Lower Dam (Forest Glen Drive) Reservoir Report

Last Updated: December 9, 2025

Glen Elyn Lower Dam, located in the Moores Road Area of Harford, Maryland, is a recreational Earth dam built in 1975 with a height of 21.5 feet and a hydraulic height of 17 feet.


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Summary

The dam serves primarily for recreation purposes, providing a surface area of 1.8 acres and a normal storage capacity of 8.5 acre-feet. The dam is situated on the Little Gunpower Falls-TR river, within the Philadelphia District of the US Army Corps of Engineers.

Despite being categorized as having a significant hazard potential, Glen Elyn Lower Dam is assessed to be in fair condition as of April 2021. The dam underwent structural modifications in 2009 and is inspected every three years. Its spillway type is uncontrolled, with a maximum discharge capacity of 170 cubic feet per second. The dam is regulated by the Maryland Dam Safety agency and has state permits for operation, inspection, and enforcement.

Overall, Glen Elyn Lower Dam is a vital recreational structure in the Moores Road Area, offering opportunities for water-based activities and leisure. With its moderate risk assessment and fair condition, the dam continues to be an important feature for water resource and climate enthusiasts to appreciate and monitor for safety and regulatory compliance.

Years Modified

2009 - Structural

Year Completed

1975

Dam Length

550

Dam Height

21.5

River Or Stream

Little Gunpower Falls-TR

Primary Dam Type

Earth

Surface Area

1.8

Hydraulic Height

17

Drainage Area

0.18

Nid Storage

21

Structural Height

21

Outlet Gates

Needle - 0

Hazard Potential

Significant

Foundations

Soil

Nid Height

22
       
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.