Three Mile Creek Watershed Site U-2 Reservoir Report

Last Updated: December 12, 2025

Three Mile Creek Watershed Site U-2 in Union, Iowa is a crucial water resource managed by the local government and designed by the USDA NRCS.


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Summary

This site serves multiple purposes, including fire protection, stock, and small fish pond management, as well as flood risk reduction. The earth dam, completed in 1980, stands at 26 feet in height and has a storage capacity of 137 acre-feet, with a normal storage of 38 acre-feet over a surface area of 8 acres.

Despite its low hazard potential and moderate risk assessment, the dam's condition remains unrated, with no recent inspections or emergency preparedness assessments recorded. The dam's spillway is uncontrolled, and there are no outlet gates or associated structures. The site's location along Three Mile Creek provides valuable insight into water resource management and climate resilience efforts in the area, making it an important focal point for water resource and climate enthusiasts looking to understand the intersection of infrastructure, regulation, and environmental conservation in Iowa.

Year Completed

1980

Dam Length

720

Dam Height

26

River Or Stream

TR-THREE MILE CREEK

Primary Dam Type

Earth

Surface Area

8

Drainage Area

0.42

Nid Storage

137

Hazard Potential

Low

Foundations

Soil

Nid Height

26
       
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.