Hanthorn Dam Reservoir Report
Last Updated: December 10, 2025
Hanthorn Dam, located in Decatur County, Iowa, is a private earth dam constructed in 1991 by the USDA NRCS.
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Summary
With a height of 27 feet and a length of 430 feet, this dam serves multiple purposes including fire protection, stock, and small fish pond management. The dam has a storage capacity of 32 acre-feet and covers a surface area of 2.3 acres, receiving water from TR- Little River in the area.
Managed by the Iowa Department of Natural Resources, Hanthorn Dam is regulated and inspected regularly to ensure its safety and functionality. Despite being classified as a low hazard potential structure, the dam is considered to have moderate risk due to its location and characteristics. While the condition assessment of the dam is not rated, measures for risk management and emergency preparedness are in place to mitigate any potential risks associated with its operation.
For water resource and climate enthusiasts, Hanthorn Dam presents an interesting case study in private dam management and the importance of regulatory oversight in ensuring the safety and efficiency of such structures. With its unique location in the Little River Lake area and its multiple purposes, the dam serves as a crucial water resource for the surrounding community while also posing certain risks that need to be managed effectively. Overall, Hanthorn Dam stands as a testament to the intricate balance between water resource utilization and environmental conservation in the face of changing climate patterns.
Year Completed |
1991 |
Dam Length |
430 |
Dam Height |
27 |
River Or Stream |
TR- LITTLE RIVER |
Primary Dam Type |
Earth |
Surface Area |
2.3 |
Drainage Area |
0.09 |
Nid Storage |
32 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
27 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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.
Hanthorn Dam