Twelvemile Watershed Site D-60 Reservoir Report
Nearby: Beattie Dam Beattle Dam
Last Updated: December 12, 2025
Twelvemile Watershed Site D-60 in Union, Iowa, is a vital water resource managed by the local government with oversight from the Iowa Department of Natural Resources.
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Summary
This earth dam, completed in 1999 by the USDA NRCS, serves multiple purposes including fire protection, stock watering, and flood risk reduction. With a height of 35 feet and a storage capacity of 497 acre-feet, this dam plays a crucial role in managing water resources in the region.
Situated along Twelvemile Creek, this dam covers a surface area of 14.9 acres and has a drainage area of 1.66 square miles. Despite its uncontrolled spillway type and low hazard potential, the dam is rated as being in moderate risk condition. With no recent inspection data available, the risk management measures and emergency preparedness of this site remain unclear. Overall, Twelvemile Watershed Site D-60 stands as a significant infrastructure for water management and conservation efforts in the area, contributing to the environmental sustainability of the region.
As a key component of the water infrastructure in Afton, Iowa, Twelvemile Watershed Site D-60 embodies the collaborative efforts of various agencies and stakeholders. With its primary purpose being fire protection and stock watering, this dam also provides essential flood risk reduction benefits to the community. While the dam's condition assessment is currently not rated, its role in managing water resources and mitigating potential hazards underscores the importance of ongoing monitoring and maintenance to ensure its continued functionality for the region's water supply and environmental health.
Year Completed |
1999 |
Dam Length |
611 |
Dam Height |
35 |
River Or Stream |
TR- TWELVEMILE CREEK |
Primary Dam Type |
Earth |
Surface Area |
14.9 |
Drainage Area |
1.66 |
Nid Storage |
497 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
35 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Thompson River At Davis City
|
22cfs |
East Fork 102 River At Bedford
|
1cfs |
Raccoon River At Van Meter
|
1640cfs |
South Raccoon River At Redfield
|
268cfs |
Raccoon River Near West Des Moines
|
1300cfs |
North River Near Norwalk
|
48cfs |
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.
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