Patterson Dam Reservoir Report
Nearby: Oswald Dam High Prairie Farms Dam
Last Updated: December 11, 2025
Patterson Dam, located in Indianola, Iowa, is a privately owned structure designed by USDA NRCS and completed in 2018 for grade stabilization purposes.
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Summary
The dam stands at a height of 32 feet and spans a length of 447 feet, with a storage capacity of 57 acre-feet and a surface area of 4 acres. It serves multiple purposes, including grade stabilization, recreation, and water supply for the surrounding area.
Managed by the Iowa DNR and regulated by the state, Patterson Dam has a low hazard potential and is currently not rated for its condition assessment. Despite its moderate risk level, the dam has not been modified since completion, and its emergency action plan status and risk management measures remain unreported. With a spillway width of 20 feet and uncontrolled outlet gates, the dam plays a crucial role in managing water resources in the region and ensuring the safety of downstream communities in the event of a flood or emergency situation.
As a key infrastructure in the tributary to Squaw Creek, Patterson Dam contributes to the overall resilience of the water management system in Clarke County, Iowa. With its strategic location and design, the dam plays a vital role in mitigating erosion, providing recreational opportunities, and supporting water supply needs. Continuous monitoring and maintenance efforts are essential to ensure the long-term effectiveness and safety of Patterson Dam for both water resource and climate enthusiasts in the region.
Year Completed |
2018 |
Dam Length |
447 |
Dam Height |
32 |
River Or Stream |
Trib to Squaw Creek |
Primary Dam Type |
Earth |
Surface Area |
4 |
Drainage Area |
0.16 |
Nid Storage |
57 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
32 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
South River Near Ackworth
|
18cfs |
Middle River Near Indianola
|
48cfs |
North River Near Norwalk
|
48cfs |
Raccoon River Near West Des Moines
|
1300cfs |
Raccoon River At Van Meter
|
1640cfs |
White Breast Creek Near Dallas
|
5cfs |
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.
Patterson Dam