Seneca State Park Dam (Seneca Creek Road) Reservoir Report

Last Updated: December 5, 2025

Seneca State Park Dam, also known as Clopper Lake, is a picturesque recreational spot located in Montgomery County, Maryland.


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Summary

Built in 1975, this earth dam stands at a height of 64 feet and stretches 580 feet in length, creating a serene 90-acre surface area for visitors to enjoy. The dam serves multiple purposes, including flood risk reduction and recreation, making it a vital asset in the area.

Managed by the Maryland Dam Safety agency, Seneca State Park Dam is subject to regular state inspections and enforcement measures to ensure its structural integrity and safety. With a high hazard potential due to its location on Long Draught Branch, the dam is classified as having a fair condition assessment as of June 2020. Despite its moderate risk assessment, the dam continues to be a popular destination for water resource and climate enthusiasts seeking outdoor activities in the Dawsonville area.

As one of the key features in Seneca Creek State Park, visitors can explore the natural beauty of the surrounding area, participate in water-based activities, or simply relax by the peaceful waters of Clopper Lake. With its rich history, stunning views, and important role in flood risk management, Seneca State Park Dam remains a significant landmark for both locals and tourists alike.

Year Completed

1975

Dam Length

580

Dam Height

64

River Or Stream

Long Draught Branch

Primary Dam Type

Earth

Surface Area

90

Drainage Area

2.9

Nid Storage

2792

Outlet Gates

Slide (sluice gate) - 0

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

64
       
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.