Janssen Lake Dam Reservoir Report

Last Updated: December 8, 2025

Located in Washington, Missouri, Janssen Lake Dam stands as a testament to engineering ingenuity and resource management.


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Summary

Built in 1974, this earth dam measures 30 feet in height and serves as a crucial water resource for the surrounding area. With a storage capacity of 96 acre-feet and a drainage area of 43 square miles, the dam plays a vital role in managing water flow and maintaining ecological balance in the region.

Despite being privately owned and not regulated by the state, Janssen Lake Dam boasts a low hazard potential and has not been rated for condition assessment. The dam primarily serves as a water source for recreational purposes and wildlife conservation, with a surface area of 6 acres and a normal storage capacity of 55 acre-feet. Although lacking certain safety measures such as an Emergency Action Plan and updated inspection reports, the dam remains a key feature in the local landscape and a symbol of sustainable water resource management.

For water resource and climate enthusiasts, Janssen Lake Dam presents a fascinating case study in balancing human needs with environmental stewardship. With its unique design and historical significance, the dam serves as a reminder of the delicate interplay between infrastructure development, water conservation, and ecosystem preservation. As discussions around climate change and water scarcity continue to gain momentum, the lessons learned from Janssen Lake Dam can offer valuable insights into sustainable resource management practices for the future.

Year Completed

1974

Dam Height

30

River Or Stream

TR TO ST JOHNS CREEK

Primary Dam Type

Earth

Surface Area

6

Drainage Area

43

Nid Storage

96

Structural Height

30

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

30
       
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.