Grimm Dam Reservoir Report

Last Updated: December 15, 2025

Grimm Dam, located in Louisa, Iowa, along the TR-Iowa River, was completed in 1987 by the Soil Conservation Service (SCS) and is privately owned.


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Summary

This earth dam stands at 38 feet in height and stretches 260 feet in length, with a storage capacity of 112 acre-feet. The primary purposes of Grimm Dam are fire protection, stock, and serving as a small fish pond, making it a valuable resource for the local community.

Managed by the Iowa Department of Natural Resources, Grimm Dam is regulated, permitted, inspected, and enforced by state authorities to ensure its safety and compliance with regulations. The dam has a low hazard potential and a moderate risk assessment rating of 3, indicating a need for ongoing risk management measures. Despite its uncontrolled spillway type, Grimm Dam plays a crucial role in water resource management, supporting irrigation, wildlife habitat, and recreational activities in the area.

For water resource and climate enthusiasts, Grimm Dam offers a fascinating example of earth dam construction and management in the Midwest. With its strategic location and design, this dam contributes to the sustainable use of water resources and provides essential services for fire protection, livestock, and fisheries. As climate change continues to impact water availability and quality, dams like Grimm play a vital role in mitigating risks and ensuring the resilience of communities in the face of environmental challenges.

Year Completed

1987

Dam Length

260

Dam Height

38

River Or Stream

TR- IOWA RIVER

Primary Dam Type

Earth

Surface Area

5.4

Drainage Area

0.33

Nid Storage

112

Hazard Potential

Low

Foundations

Soil

Nid Height

38
       
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.