Hanlontown Slough Dam 1.1 Reservoir Report

Last Updated: December 6, 2025

Hanlontown Slough Dam 1.1, located in Worth County, Iowa, is a Federal-owned structure designed by NRCS for the primary purpose of serving as a Fish and Wildlife Pond.


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Summary

Completed in 2001, this Earth-type dam stands at a height of 11 feet and spans a length of 938 feet, with a storage capacity of 191 acre-feet. The dam is situated on TR- Willow Creek and is regulated by the Iowa Department of Natural Resources, with state permitting, inspection, and enforcement in place.

With a low hazard potential and a moderate risk assessment rating, Hanlontown Slough Dam 1.1 plays a crucial role in managing water resources and supporting wildlife in the area. The dam's surface area of 14 acres and drainage area of 0.75 square miles contribute to its function as a habitat for fish and wildlife. Despite being in a moderate-risk category, the dam's condition assessment is currently not rated, highlighting the need for ongoing monitoring and maintenance to ensure its continued safety and effectiveness.

As a key feature in the St. Paul District managed by the US Army Corps of Engineers, Hanlontown Slough Dam 1.1 serves as a vital component in the local ecosystem, providing valuable benefits for both wildlife and the surrounding community. Its presence along TR- Willow Creek underscores its significance in water resource management and conservation efforts, making it a focal point for water resource and climate enthusiasts interested in sustainable infrastructure and environmental stewardship.

Year Completed

2001

Dam Length

938

Dam Height

11

River Or Stream

TR- WILLOW CREEK

Primary Dam Type

Earth

Surface Area

14

Drainage Area

0.75

Nid Storage

191

Hazard Potential

Low

Foundations

Soil

Nid Height

11
       
Seasonal Comparison

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Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.