Johnson Dam Reservoir Report

Last Updated: December 8, 2025

Johnson Dam, located in Lucas County, Iowa, is a privately owned earth dam with a primary purpose of fire protection, stock, or small fish pond.


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Summary

Built in 1972 by the USDA NRCS, this dam stands at a height of 31 feet and spans 295 feet in length, with a storage capacity of 38 acre-feet. The dam is regulated by the Iowa DNR and undergoes regular inspections to ensure its safety and compliance with state regulations.

Situated on TR-WHITEBREAST CREEK near RED ROCK RESERVOIR, Johnson Dam serves as a recreational site in addition to its primary functions. The dam has a low hazard potential and a moderate risk assessment rating, indicating a manageable level of risk. While the dam's condition assessment is currently listed as "Not Rated," it is subject to periodic inspections and enforcement to maintain its integrity and safeguard against potential hazards.

Despite being a private structure, Johnson Dam plays a crucial role in water resource management in the region, providing storage capacity, fire protection, and recreational opportunities. With its strategic location and functional design, the dam serves as a vital asset for the community while contributing to the overall sustainability of the area's water resources and climate resilience efforts.

Year Completed

1972

Dam Length

295

Dam Height

31

River Or Stream

TR-WHITEBREAST CREEK

Primary Dam Type

Earth

Surface Area

2.9

Drainage Area

0.19

Nid Storage

38

Hazard Potential

Low

Foundations

Soil

Nid Height

31
       
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.