U-B Subwatershed Site 2-2 Reservoir Report
Last Updated: December 13, 2025
U-B Subwatershed Site 2-2, located in Monona, Iowa, is a vital water resource managed by the local government with assistance from the USDA NRCS.
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Summary
This earth dam, completed in 1962, serves multiple purposes including fire protection, stock, small fish pond, and flood risk reduction. With a dam height of 51 feet and a storage capacity of 225 acre-feet, this structure plays a crucial role in water management in the area.
Despite being rated as low hazard potential and not currently assessed for condition, U-B Subwatershed Site 2-2 is still regulated by the Iowa DNR, with state permitting, inspection, and enforcement in place. The dam's primary source agency is IA, and it is situated on the TR-Little Sioux River, within the Rock Island District. The risk assessment for this site is moderate, indicating the need for ongoing monitoring and management to ensure its continued safety and effectiveness in mitigating flood risks and providing water resources for the surrounding community.
As a valuable asset in the region's water infrastructure, U-B Subwatershed Site 2-2 demonstrates the importance of proactive management and regulation in safeguarding water resources and reducing flood risks. With its strategic location, diverse purposes, and moderate risk assessment, this site serves as a key example of how effective collaboration between local government agencies and federal partners can help address climate challenges and ensure water security for communities in Iowa and beyond.
Year Completed |
1962 |
Dam Length |
366 |
Dam Height |
51 |
River Or Stream |
TR-LITTLE SIOUX RIVER |
Primary Dam Type |
Earth |
Surface Area |
10.4 |
Drainage Area |
0.42 |
Nid Storage |
225 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
51 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Little Sioux River Near Turin
|
1040cfs |
Maple River At Mapleton
|
323cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
Soldier River At Pisgah
|
112cfs |
West Fork Ditch At Hornick
|
80cfs |
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.
U-B Subwatershed Site 2-2