Lewis Dam Reservoir Report
Nearby: Hughes Dam Ever-Tru Pond
Last Updated: December 14, 2025
Lewis Dam, located in Union Mills, Iowa, along the TR-North Skunk River, was completed in 1963 by the USDA NRCS.
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Summary
This private dam serves primarily for fire protection, stock, or small fish pond purposes, with a height of 25 feet and a length of 327 feet. The dam has a storage capacity of 45 acre-feet, with a normal storage level of 25 acre-feet and a surface area of 4 acres. Despite its low hazard potential and moderate risk assessment, the dam's condition is currently not rated, and it is not regularly inspected.
Managed by the Iowa Department of Natural Resources, Lewis Dam is regulated, permitted, inspected, and enforced by state authorities to ensure its safety and compliance with regulations. The dam features an uncontrolled spillway type and is constructed with an earth foundation and soil core. While the dam has not been modified in recent years and lacks certain emergency preparedness measures, it remains a key structure for water resource management in the region. The dam's location, design, and purpose make it a vital component in the local ecosystem and water supply infrastructure.
Water resource and climate enthusiasts will find Lewis Dam intriguing for its historical significance, structural design, and environmental impact. As a privately owned dam with state oversight, Lewis Dam showcases the importance of balancing water management needs with regulatory requirements. With its unique characteristics and role in fire protection and stock pond maintenance, Lewis Dam serves as a focal point for understanding the intersection of human development and natural resource conservation in the context of climate change and water sustainability.
Year Completed |
1963 |
Dam Length |
327 |
Dam Height |
25 |
River Or Stream |
TR-NORTH SKUNK RIVER |
Primary Dam Type |
Earth |
Surface Area |
4 |
Drainage Area |
0.25 |
Nid Storage |
45 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
25 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
South Skunk River Near Oskaloosa
|
485cfs |
Des Moines River Near Pella
|
2440cfs |
Des Moines River Near Tracy
|
1400cfs |
Walnut Creek Near Hartwick
|
13cfs |
Cedar Creek Near Bussey
|
11cfs |
English Creek Near Knoxville
|
2cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Robertson Access
|
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Diamond Lake County Park
|
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Union Mills Access
|
Lewis Dam