Johnson Dam Reservoir Report
Nearby: Berndt Dam Beedle Dam
Last Updated: December 13, 2025
Johnson Dam, located in Pottawattamie County, Iowa, is a privately owned structure designed by the USDA NRCS for fire protection, stock, or small fish pond purposes.
°F
°F
mph
Wind
%
Humidity
Summary
Completed in 1959, the earth dam stands at a height of 27 feet and spans 472 feet in length, with a storage capacity of 80 acre-feet. Situated on the TR-West Nishnabota River, the dam serves as a vital resource for water management and conservation in the region.
Despite its low hazard potential and moderate risk assessment, Johnson Dam is regulated by the Iowa Department of Natural Resources and undergoes regular inspections to ensure its structural integrity. The dam has not been rated for its current condition, but its primary purpose and design indicate its importance in safeguarding against wildfires, supporting livestock, and providing habitat for small fish populations. With a surface area of 5.2 acres and a drainage area of 0.52 square miles, Johnson Dam plays a crucial role in maintaining water quality and quantity in the area.
As a key feature in the local water infrastructure, Johnson Dam's uncontrolled spillway and soil foundation highlight its reliance on natural resources for operation. While the dam has not been modified in recent years, its historic significance and ongoing regulatory oversight underscore the importance of sustainable water resource management in mitigating climate-related risks. For water resource and climate enthusiasts, Johnson Dam serves as a case study in balancing human needs with environmental stewardship to ensure the resilience of water systems in the face of changing weather patterns and increasing demands.
Year Completed |
1959 |
Dam Length |
472 |
Dam Height |
27 |
River Or Stream |
TR-WEST NISHNABOTA RIVER |
Primary Dam Type |
Earth |
Surface Area |
5.2 |
Drainage Area |
0.52 |
Nid Storage |
80 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
27 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
West Nishnabotna River At Hancock
|
154cfs |
East Nishnabotna River Near Atlantic
|
143cfs |
Boyer River At Logan
|
417cfs |
East Nishnabotna River At Red Oak
|
270cfs |
Missouri River At Omaha
|
17700cfs |
West Nishnabotna River At Randolph
|
420cfs |
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.
Pottawattamie County Fairgrounds
Botna Bend County Park
Nishna Bend Rec Area
Lyons Park
Prairie Rose State Park West Campground
Prairie Rose State Park
Johnson Dam