Union County Roadgrade Dam 29-73-29 Reservoir Report

Last Updated: December 12, 2025

Union County Roadgrade Dam 29-73-29, located in Afton, Iowa, is a local government-owned structure designed by the Soil Conservation Service (SCS) and completed in 1993.


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Summary

This earth dam stands at a height of 39 feet and spans 435 feet, with a storage capacity of 59 acre-feet and a drainage area of 0.12 square miles. Situated on TR- Three Mile Creek, the dam serves a primary purpose of "Other" and is state-regulated by the Iowa Department of Natural Resources.

With a low hazard potential and a moderate risk assessment rating of 3, Union County Roadgrade Dam 29-73-29 is currently in "Not Rated" condition. While it lacks a formal Emergency Action Plan (EAP) and updated inspection dates, the dam meets state permitting and inspection requirements. The dam's spillway type is classified as "Uncontrolled," with no outlet gates or locks present. Despite its operational status, the dam's risk management measures and inundation maps have yet to be fully developed.

For water resource and climate enthusiasts, Union County Roadgrade Dam 29-73-29 presents an intriguing case study in dam infrastructure and regulation. With its unique design features and location in Union County, Iowa, this earth dam provides valuable insights into the management and assessment of water resources in the region. As efforts continue to enhance the dam's safety and emergency preparedness measures, stakeholders can track its progress towards achieving a higher condition rating and reducing potential risks associated with its operation.

Year Completed

1993

Dam Length

435

Dam Height

39

River Or Stream

TR- THREE MILE CREEK

Primary Dam Type

Earth

Surface Area

2

Drainage Area

0.12

Nid Storage

59

Hazard Potential

Low

Foundations

Soil

Nid Height

39
       
Seasonal Comparison

Weather Forecast

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.