Zellmer Subwatershed Site J-1a Reservoir Report
Last Updated: December 13, 2025
Zellmer Subwatershed Site J-1a, located in Climbing Hill, Iowa, is a flood risk reduction structure designed by the USDA NRCS and completed in 2002.
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Summary
This earth dam stands at a height of 42 feet and spans 460 feet, with a storage capacity of 70 acre-feet. It serves the primary purpose of flood risk reduction along the TR- West Fork Little Sioux River and is regulated by the Iowa DNR.
With a low hazard potential and a moderate risk assessment rating, Zellmer Subwatershed Site J-1a plays a crucial role in managing water resources in Woodbury County, Iowa. Despite not being rated for its condition assessment, this structure has not experienced any major modifications or incidents. Its uncontrolled spillway and soil foundation contribute to its effectiveness in mitigating flood risks in the area.
Water resource and climate enthusiasts will find Zellmer Subwatershed Site J-1a to be an intriguing example of sustainable flood risk reduction infrastructure in the region. Its location, design, and purpose highlight the importance of proactive water management strategies in addressing the challenges posed by changing climate patterns and increasing development pressures. As a state-regulated and inspected structure with a history of successful operation, this site serves as a model for resilient water resource management practices in the face of environmental uncertainties.
Year Completed |
2002 |
Dam Length |
460 |
Dam Height |
42 |
River Or Stream |
TR- WEST FORK LITTLE SIOUX RIVER |
Primary Dam Type |
Earth |
Surface Area |
4.6 |
Drainage Area |
0.16 |
Nid Storage |
70 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
42 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
West Fork Ditch At Hornick
|
80cfs |
Floyd River At James
|
187cfs |
Missouri River At Sioux City
|
15100cfs |
Little Sioux River At Correctionville
|
327cfs |
Omaha Cr At Homer
|
45cfs |
Perry Creek Near Milnerville
|
25cfs |
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.
Zellmer Subwatershed Site J-1a