Valley Mall Expansion Swm Dam Reservoir Report

Last Updated: December 5, 2025

The Valley Mall Expansion Swm Dam in Williamsport, Maryland, is a private dam constructed in 1987 primarily for flood risk reduction along the Conococheague-TR-Semple Run river.


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Summary

The dam is an earth-core type structure with a height of 19 feet and a hydraulic height of 16 feet, providing a maximum storage capacity of 58 acre-feet. With a low hazard potential and moderate risk rating, the dam serves as a critical infrastructure for managing stormwater and protecting the surrounding area from potential flooding events.

Managed by the Maryland Dam Safety regulatory agency, the Valley Mall Expansion Swm Dam undergoes regular inspections and enforcement to ensure its structural integrity and operational efficiency. Despite being uncontrolled, the dam features a spillway with a width of 25 feet to manage excess water flow during periods of heavy rainfall. The dam's location within the Baltimore District and its close proximity to Washington County makes it a key piece of infrastructure contributing to the overall water resource management and climate resilience efforts in the region.

As water resource and climate enthusiasts, understanding the design and purpose of the Valley Mall Expansion Swm Dam sheds light on the importance of flood risk reduction and infrastructure maintenance in mitigating potential hazards. By recognizing the role of private dams like this one in safeguarding communities and ecosystems from the impacts of extreme weather events, we can advocate for sustainable water management practices and continued investment in critical infrastructure to adapt to changing climate conditions.

Year Completed

1987

Dam Length

1900

Dam Height

19

River Or Stream

Conococheague-TR-Semple Run

Primary Dam Type

Earth

Surface Area

2

Hydraulic Height

16

Drainage Area

0.06

Nid Storage

58

Hazard Potential

Low

Foundations

Soil

Nid Height

19
       
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.