Zellmer Subwtrshd Sta 31+70 #M Reservoir Report
Last Updated: December 14, 2025
Zellmer Subwtrshd Sta 31+70 #M is a local government-owned dam located in Woodbury County, Iowa, specifically in the city of ROLLY SPRINGS.
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Summary
Constructed in 1964 by the USDA NRCS, this earth dam has a height of 42 feet and a length of 407 feet, with a primary purpose of providing fire protection, stock, or small fish pond, as well as flood risk reduction. With a normal storage capacity of 19 acre-feet and a drainage area of 0.18 square miles, this dam serves as a valuable resource for the surrounding community.
Managed by the Iowa Department of Natural Resources, Zellmer Subwtrshd Sta 31+70 #M is regulated by state authorities for inspection, permitting, and enforcement. The dam has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment, with a moderate risk level identified. While it does not have a specific Emergency Action Plan (EAP) prepared, the dam has not undergone any recent modifications and has not required any major risk management measures to be implemented. Overall, this dam plays a crucial role in water resource management and protection in the area.
Located along the TR-WEST FORK LITTLE SIOUX RIV, Zellmer Subwtrshd Sta 31+70 #M provides important benefits for fire protection, stock water supply, and flood risk reduction in the region. With a focus on maintaining public safety and environmental sustainability, this dam stands as a key infrastructure for water resource and climate enthusiasts to monitor and support.
Year Completed |
1964 |
Dam Length |
407 |
Dam Height |
42 |
River Or Stream |
TR-WEST FORK LITTLE SIOUX RIV |
Primary Dam Type |
Earth |
Surface Area |
1.9 |
Drainage Area |
0.18 |
Nid Storage |
34 |
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
|
13700cfs |
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 Subwtrshd Sta 31+70 #M