Lewis Dam Reservoir Report

Last Updated: December 5, 2025

Lewis Dam, located in Mills River, North Carolina, is a private recreational structure along Osborne Branch, boasting a hydraulic height of 16 feet and a structural height of 18 feet.


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Summary

With a storage capacity of 10 acre-feet and a surface area of 1 acre, this earthen dam provides essential water resources for both recreational purposes and environmental conservation in the area. Despite its fair condition assessment as of May 2018, the dam poses a high hazard potential, requiring regular inspections every two years to ensure public safety and the integrity of the structure.

Owned and regulated by the North Carolina Department of Environmental Quality's Dam Safety Program, Lewis Dam stands as a testament to responsible water management practices in the region. The dam's primary purpose is to provide a safe and enjoyable recreational space for the community while also supporting conservation efforts for the surrounding natural habitats. With a strong emphasis on state permitting, inspection, and enforcement, Lewis Dam demonstrates a commitment to sustainability and environmental stewardship in the face of climate change and shifting water resource dynamics.

As a vital component of the local watershed, Lewis Dam plays a crucial role in managing water flow, storage, and distribution in Transylvania County. With a focus on risk management measures and emergency preparedness, the dam serves as a model for sustainable water infrastructure development in the region. Climate enthusiasts and water resource advocates alike can appreciate Lewis Dam's dedication to balancing human recreation with ecological preservation in the face of evolving environmental challenges.

Dam Length

150

River Or Stream

Osborne Branch

Primary Dam Type

Earth

Surface Area

1

Hydraulic Height

16

Nid Storage

10

Structural Height

18

Hazard Potential

High

Nid Height

18
       
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.