Great Falls Estate Dam Reservoir Report

Last Updated: December 5, 2025

Great Falls Estate Dam, located in Montgomery, Maryland, is a privately owned structure primarily designed for recreation and flood risk reduction along the Cool Spring Branch river.


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Summary

Constructed in 1963 by Robert A. Goves & Assoc., this earth dam stands at a height of 34 feet and is 300 feet long, with a storage capacity of 134 acre-feet. Despite its low hazard potential, the dam remains state-regulated and regularly inspected by Maryland Dam Safety.

With a spillway width of 18 feet and a maximum discharge of 160 cubic feet per second, Great Falls Estate Dam plays a crucial role in managing water flow and ensuring the safety of surrounding areas. The dam's risk assessment indicates a moderate level of risk, emphasizing the importance of ongoing monitoring and maintenance to prevent potential hazards. Although the condition assessment is currently not rated, the dam's emergency action plan readiness and compliance with guidelines are areas for improvement.

As a key structure in the region, Great Falls Estate Dam serves as a significant asset for both water resource management and recreational activities. With its unique design and historical significance, the dam continues to attract water resource and climate enthusiasts seeking to appreciate its engineering marvel and environmental impact on the surrounding watershed.

Year Completed

1963

Dam Length

300

Dam Height

34

River Or Stream

Cool Spring Branch

Primary Dam Type

Earth

Surface Area

5.4

Drainage Area

0.3

Nid Storage

134

Hazard Potential

Low

Foundations

Rock

Nid Height

34
       
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.