West Sunnyside Watershed Site A-1 Reservoir Report
Last Updated: December 15, 2025
West Sunnyside Watershed Site A-1 is a local government-owned earth dam located in Sioux City, Iowa, designed by USDA NRCS and completed in 1969.
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Summary
This dam serves multiple purposes including fire protection, stock, and small fish pond, as well as flood risk reduction. With a height of 38 feet and a length of 417 feet, the dam has a storage capacity of 70 acre-feet and covers a surface area of 3.8 acres, draining an area of 0.37 square miles.
Managed by the Iowa DNR, this watershed site on TR-Broken Kettle Creek has a low hazard potential and is classified as having a moderate risk level. The dam features an uncontrolled spillway and is inspected, permitted, and regulated by state authorities. Despite not being rated for condition assessment, the dam has not undergone any modifications since its completion and does not have an Emergency Action Plan (EAP) in place. With its critical role in water resource management and flood prevention, West Sunnyside Watershed Site A-1 is an essential infrastructure for the local community.
For water resource and climate enthusiasts, West Sunnyside Watershed Site A-1 offers a fascinating case study in dam engineering and management practices. As a key element in the regional water infrastructure, this earth dam exemplifies the balance between multiple water usage purposes and flood risk mitigation. With its location in Plymouth County, Iowa, and oversight by the Iowa DNR, the site presents an opportunity for further research and analysis on sustainable water resource management in the face of changing climate conditions.
Year Completed |
1969 |
Dam Length |
417 |
Dam Height |
38 |
River Or Stream |
TR-BROKEN KETTLE CREEK |
Primary Dam Type |
Earth |
Surface Area |
3.8 |
Drainage Area |
0.37 |
Nid Storage |
70 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
38 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Perry Creek Near Milnerville
|
25cfs |
Big Sioux River At Akron
|
816cfs |
Floyd River At James
|
187cfs |
Missouri River At Sioux City
|
13700cfs |
Vermillion River Nr Vermillion Sd
|
33cfs |
Omaha Cr At Homer
|
45cfs |
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.
West Sunnyside Watershed Site A-1
220th Street Plymouth County