Arnold-Armstrong Subwtrshd Gully 23 Reservoir Report
Last Updated: December 14, 2025
Arnold-Armstrong Subwtrshd Gully 23 is a significant earth dam located in Monona, Iowa, with a primary purpose of fire protection, stock, or small fish pond.
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Summary
Completed in 1961, this dam has a height of 36 feet and a length of 470 feet, providing a storage capacity of 35 acre-feet. The dam is owned and regulated by the local government, with oversight from the Iowa Department of Natural Resources.
The dam's condition assessment in 2015 rated it as fair, with a significant hazard potential. Despite its moderate risk assessment, the dam has not been modified in recent years and lacks emergency action plans and inundation maps. The surrounding area, which includes the TR-MAPLE RIVER, is at risk of flooding, making it crucial for proper management and maintenance of the dam to ensure the safety of the community.
With its location in a rural area prone to flooding, the Arnold-Armstrong Subwtrshd Gully 23 serves as a crucial infrastructure for flood risk reduction. As water resource and climate enthusiasts, it is important to monitor the condition of this dam and advocate for necessary updates and emergency preparedness measures to protect the surrounding environment and communities from potential disasters.
Year Completed |
1961 |
Dam Length |
470 |
Dam Height |
36 |
River Or Stream |
TR-MAPLE RIVER |
Primary Dam Type |
Earth |
Surface Area |
1.6 |
Drainage Area |
0.32 |
Nid Storage |
35 |
Hazard Potential |
Significant |
Foundations |
Soil |
Nid Height |
36 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Maple River At Mapleton
|
323cfs |
Little Sioux River Near Turin
|
1040cfs |
West Fork Ditch At Hornick
|
80cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
Soldier River At Pisgah
|
112cfs |
Missouri River At Decatur
|
14900cfs |
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.
Arnold-Armstrong Subwtrshd Gully 23