Phillips Subwatershed Site 131 Reservoir Report
Last Updated: December 13, 2025
Phillips Subwatershed Site 131, located in Monona, Iowa, is a locally owned earth dam with a primary purpose of providing fire protection, stock, or a small fish pond.
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Summary
Built in 1956, this dam has a height of 26 feet and a storage capacity of 50 acre-feet, serving the Maple River. With a surface area of 4 acres and a drainage area of 0.18 square miles, this dam plays a crucial role in flood risk reduction in the area.
Managed by the Iowa Department of Natural Resources, Phillips Subwatershed Site 131 is classified as having a low hazard potential and a moderate risk level. Despite not being rated for its current condition, this dam meets state regulations for inspection, permitting, and enforcement. The dam features an uncontrolled spillway type and has not been modified in recent years, indicating a stable and well-maintained structure that contributes to the overall water resource management and climate resilience efforts in the region.
With its strategic location and functional design, Phillips Subwatershed Site 131 serves as a vital component in the water management infrastructure of Monona County. This dam not only provides essential services for fire protection and agricultural activities but also helps mitigate flood risks in the area. As climate change impacts continue to pose challenges to water resources, this dam stands as a testament to successful collaboration between local government agencies and the Natural Resources Conservation Service in ensuring the safety and sustainability of water resources in the region.
Year Completed |
1956 |
Dam Height |
26 |
River Or Stream |
TR- MAPLE RIVER |
Primary Dam Type |
Earth |
Surface Area |
4 |
Drainage Area |
0.18 |
Nid Storage |
50 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
26 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Maple River At Mapleton
|
323cfs |
Little Sioux River Near Turin
|
1040cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
West Fork Ditch At Hornick
|
80cfs |
Soldier River At Pisgah
|
112cfs |
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.
Phillips Subwatershed Site 131