Hagerstown Municipal Pwr Plant Dam Reservoir Report

Last Updated: December 5, 2025

The Hagerstown Municipal Power Plant Dam, also known as the Mt Aetna Dam, is a privately owned structure located in Washington County, Maryland.


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Summary

This earth dam was completed in 1950 and serves primarily as a water supply source, with a storage capacity of 60 acre-feet and a normal storage level of 48 acre-feet. The dam spans a length of 250 feet and has a height of 10 feet, impounding water from the Antietam Creek.

Managed by the Maryland Dam Safety agency, the Hagerstown Municipal Power Plant Dam has a low hazard potential and is currently rated in fair condition. The spillway, with a width of 250 feet, is uncontrolled, allowing excess water to safely flow downstream. The dam's drainage area is 176.2 square miles, with a maximum discharge capacity of 775 cubic feet per second. Despite its moderate risk assessment, the dam has not been significantly modified since its construction, highlighting the importance of regular inspections and maintenance to ensure its continued safety and functionality for water resource and climate enthusiasts in the region.

Year Completed

1950

Dam Length

250

Dam Height

10

River Or Stream

Antietam Creek

Primary Dam Type

Earth

Surface Area

12

Drainage Area

176.2

Nid Storage

60

Outlet Gates

Needle - 0

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

10
       
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.