Johns Dam Reservoir Report

Last Updated: December 5, 2025

Johns Dam in Potosi, Missouri, is a privately owned Earth dam with a buttress core type that was completed in 2000.


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Summary

Situated on John's Creek, this dam stands at a height of 33 feet and has a storage capacity of 483 acre-feet, with a normal storage of 253 acre-feet. The dam serves the purpose of water resource management and contributes to flood control efforts in the area.

Despite being unregulated by the state and having a low hazard potential, Johns Dam plays a crucial role in the local ecosystem by providing a surface area of 23 acres and draining a watershed area of 1,500 acres. Its strategic location in Washington County, Missouri, ensures that it effectively manages water resources in the region. With no designated spillway and a condition assessment of 'Not Rated,' the dam's structural integrity remains a key consideration for water resource and climate enthusiasts.

With no associated structures or locks and a limited inspection frequency, Johns Dam continues to be an essential feature in the local water infrastructure. Although its risk assessment and emergency preparedness status remain unclear, the dam's contribution to water resource management and flood control in the area cannot be understated. For enthusiasts interested in the intersection of water resources and climate change, Johns Dam offers a fascinating case study of a privately owned structure that plays a vital role in maintaining the ecological balance of the region.

Year Completed

2000

Dam Height

33

River Or Stream

JOHN'S CREEK

Surface Area

23

Drainage Area

1500

Nid Storage

483

Hazard Potential

Low

Foundations

Unlisted/Unknown

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.