Larson Dam Reservoir Report
Last Updated: December 13, 2025
Larson Dam, located in Woodbury County, Iowa, serves multiple purposes including fire protection, stock maintenance, and small fish pond management.
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Summary
Completed in 1998, this earth dam stands at a height of 38 feet and spans a length of 460 feet. With a storage capacity of 66 acre-feet and a surface area of 3.6 acres, Larson Dam plays a crucial role in flood risk reduction for the surrounding area.
Managed by a private entity, Larson Dam is regulated by the Iowa Department of Natural Resources and undergoes regular inspections to ensure its structural integrity. Despite being classified as a low hazard potential structure, the dam's risk assessment indicates a moderate level of risk. With a drainage area of 0.33 square miles and a controlled spillway, Larson Dam is equipped to handle potential flooding events while maintaining the safety of the local community.
Located on TR-Miller Creek in the city of OTO, Larson Dam is a vital resource for water management in the region. With its strategic design by the NRCS and successful operation since its completion, Larson Dam stands as a testament to effective water resource management and climate resilience in the state of Iowa.
Year Completed |
1998 |
Dam Length |
460 |
Dam Height |
38 |
River Or Stream |
TR- MILLER CREEK |
Primary Dam Type |
Earth |
Surface Area |
3.6 |
Drainage Area |
0.33 |
Nid Storage |
66 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
38 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Maple River At Mapleton
|
323cfs |
West Fork Ditch At Hornick
|
80cfs |
Little Sioux River At Correctionville
|
327cfs |
Little Sioux River Near Turin
|
1040cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
Missouri River At Decatur
|
15500cfs |
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.
Larson Dam