Ottumwa Reservoir Report
Last Updated: December 6, 2025
Ottumwa is a hydroelectric facility located in Wapello, Iowa, along the Des Moines River.
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Summary
Built in 1960 and designed by Burns and McDonnell Engineering Co., this gravity dam stands at 16 feet tall and stretches 781 feet in length. With a normal storage capacity of 5000 acre-feet and a drainage area of 13,430 square miles, Ottumwa serves multiple purposes including hydroelectric power generation, recreation, and water supply.
Managed by the Federal Energy Regulatory Commission and regulated by the Iowa Department of Natural Resources, Ottumwa boasts a controlled spillway with a width of 603 feet and a maximum discharge capacity of 135,000 cubic feet per second. Despite its low hazard potential, Ottumwa is categorized as having a very high risk due to its critical importance in water resource management. Emergency action plans are in place, and the dam undergoes inspections every 3 years to ensure its safety and functionality.
For water resource and climate enthusiasts, Ottumwa represents a vital piece of infrastructure in Iowa's water management system. Its role in providing renewable energy, recreational opportunities, and water storage highlights the importance of sustainable development and resource utilization. As efforts continue to monitor and improve the dam's operations, Ottumwa remains a key player in the region's water resource management and climate resilience strategies.
Year Completed |
1960 |
Dam Length |
781 |
Dam Height |
16 |
River Or Stream |
Des Moines River |
Primary Dam Type |
Gravity |
Surface Area |
500 |
Drainage Area |
13430 |
Nid Storage |
5000 |
Outlet Gates |
Bascule - 1, Tainter (radial) - 9 |
Hazard Potential |
Low |
Foundations |
Rock |
Nid Height |
16 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Des Moines River At Ottumwa
|
1090cfs |
Fox River At Bloomfield
|
7cfs |
North Skunk River Near Sigourney
|
97cfs |
South Skunk River Near Oskaloosa
|
485cfs |
Chariton River Near Rathbun
|
15cfs |
Chariton River Near Moulton
|
34cfs |
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.
Ottumwa