Mertz Lake Dam Reservoir Report

Last Updated: December 20, 2025

Mertz Lake Dam is a privately owned structure located in St.


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Summary

Charles, Missouri, and serves primarily for recreational purposes. This earthen dam, completed in 1954, stands at a height of 24 feet and has a storage capacity of 39 acre-feet. It is situated along the TR to Creve Coeur Creek and covers a surface area of 3 acres within a drainage area of 42 square miles.

Despite its recreational function, Mertz Lake Dam poses a high hazard potential as it is not currently rated for its condition. The dam does not fall under state regulation or jurisdiction, with no permitting, inspection, or enforcement measures in place. Its Emergency Action Plan (EAP) status, risk assessment, and inundation maps remain unaddressed, reflecting potential vulnerabilities in emergency preparedness and overall risk management.

The dam's association with the Kansas City District of the US Army Corps of Engineers (USACE) is unclear, and there is limited federal involvement in its ownership, funding, design, construction, regulation, inspection, or operation. With its significant hazard potential and absence of comprehensive risk management measures, Mertz Lake Dam represents a focal point for water resource and climate enthusiasts interested in the intersection of recreational infrastructure and dam safety in the Missouri region.

Year Completed

1954

Dam Height

24

River Or Stream

TR TO CREVE COEUR CREEK

Primary Dam Type

Earth

Surface Area

3

Drainage Area

42

Nid Storage

39

Structural Height

24

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

24
       
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.