Johnson Dam Site 1 Reservoir Report
Last Updated: December 23, 2025
Johnson Dam Site 1, located in Fairfield, Iowa, is a privately owned earth dam completed in 1993 by the NRCS.
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Summary
The dam's primary purposes include fire protection, stock, or small fish pond. With a height of 27 feet and a length of 580 feet, the dam has a storage capacity of 116 acre-feet and covers a surface area of 9.8 acres. It is regulated by the Iowa DNR and is inspected, permitted, and enforced by the state.
Situated on TR- Mitchell Creek, Johnson Dam Site 1 serves as a crucial water resource for the surrounding area, with a low hazard potential and a moderate risk assessment rating. While the dam is currently deemed to be in "Not Rated" condition, its emergency action plan status, inundation maps, and risk management measures are not fully updated. The dam's location in Jefferson County, Iowa, makes it a valuable asset for water conservation and management in the region.
Overall, Johnson Dam Site 1 plays a significant role in providing essential water resources for fire protection, stock, and small fish pond purposes in Fairfield, Iowa. As a state-regulated structure with a low hazard potential, the dam ensures water storage and management in the area. However, there is room for improvement in updating emergency preparedness plans and risk management measures to enhance the dam's overall safety and resilience in the face of potential climate challenges and water resource management needs.
Year Completed |
1993 |
Dam Length |
580 |
Dam Height |
27 |
River Or Stream |
TR- MITCHELL CREEK |
Primary Dam Type |
Earth |
Surface Area |
9.8 |
Drainage Area |
0.21 |
Nid Storage |
116 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
27 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
North Skunk River Near Sigourney
|
97cfs |
Cedar Creek Near Oakland Mills
|
10cfs |
Des Moines River At Ottumwa
|
1090cfs |
Des Moines River At Keosauqua
|
1800cfs |
Big Creek Near Mt. Pleasant
|
0cfs |
Fox River At Bloomfield
|
7cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Johnson Dam Site 1