Crabbs Branch Swm Facility (Redland Road) Reservoir Report

Last Updated: December 5, 2025

Located in Twin Brook Forest, Montgomery County, Maryland, the Crabbs Branch Stormwater Management (SWM) Facility on Redland Road serves a primary purpose of recreation.


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Summary

Constructed in 1983, the earth dam stands at a height of 27 feet and spans 950 feet in length, with a storage capacity of 311 acre-feet. The facility boasts a surface area of 6.8 acres and a drainage area of 0.9 square miles, with a maximum discharge capacity of 4200 cubic feet per second.

Managed by the local government and regulated by the Maryland Dam Safety agency, the Crabbs Branch SWM Facility underwent structural modifications in 2007. Despite its high hazard potential, the facility's condition is deemed satisfactory as of the last assessment in April 2021. With an emergency action plan in place and a moderate risk assessment rating of 3, the facility continues to play a crucial role in managing stormwater and supporting recreational activities in the area. For water resource and climate enthusiasts, the Crabbs Branch SWM Facility stands as a testament to effective stormwater management and environmental stewardship in Maryland.

Years Modified

2007 - Structural

Year Completed

1983

Dam Length

950

Dam Height

27

River Or Stream

Crabbs Branch

Primary Dam Type

Earth

Surface Area

6.8

Drainage Area

0.9

Nid Storage

311

Outlet Gates

Slide (sluice gate) - 0

Hazard Potential

High

Foundations

Soil

Nid Height

27
       
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.