Prehm Dam Reservoir Report

Last Updated: December 5, 2025

Prehm Dam, located in Iowa's Henry County near Lake Geode, is a privately-owned structure designed by the USDA NRCS and regulated by the Iowa DNR.


°F

°F

mph

Wind

%

Humidity

Summary

Completed in 1986, this earth dam stands at a height of 33 feet and spans 210 feet in length, with a storage capacity of 40 acre-feet. The dam serves multiple purposes, including fire protection and creating a small fish pond, making it a valuable resource for the local community.

With a low hazard potential and a moderate risk assessment rating, Prehm Dam plays a crucial role in water management for the area. While not currently rated for its condition, the dam's construction and design by the Natural Resources Conservation Service highlight its importance in ensuring water security and safety. Its location on the TR- Cedar Creek stream and ownership by a private entity underscore the collaborative efforts needed to sustain and protect this vital water resource in Iowa.

As a key feature in the region's water infrastructure, Prehm Dam provides essential services for both fire protection and recreational use. Its controlled spillway and earth construction contribute to its functionality and overall resilience. With ongoing regulatory oversight and maintenance, Prehm Dam continues to play a significant role in water resource management and climate resilience efforts in the area.

Year Completed

1986

Dam Length

210

Dam Height

33

River Or Stream

TR- CEDAR CR.

Primary Dam Type

Earth

Surface Area

2.9

Drainage Area

0.1

Nid Storage

40

Hazard Potential

Low

Foundations

Soil

Nid Height

33
       
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.