Graessle-Rockers Lake Dam Reservoir Report

Last Updated: December 6, 2025

Located in Osage City, Missouri, the Graessle-Rockers Lake Dam stands as a recreational gem in the heart of Cole County.


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Summary

Built in 1967, this private Earth dam rises to a height of 31 feet, offering a maximum storage capacity of 249 acre-feet. With a primary purpose of recreation, the dam provides a serene escape for water resource and climate enthusiasts seeking solace in its 15-acre surface area.

Although not regulated by the state, the Graessle-Rockers Lake Dam boasts a high hazard potential, emphasizing the importance of proper maintenance and oversight. Despite its condition not being rated, the dam remains a key feature in the TR-OSAGE RIVER watershed, contributing to the drainage of a 290-acre area. As a site not under federal agency jurisdiction, the Graessle-Rockers Lake Dam serves as a testament to the importance of private ownership in preserving and managing our valuable water resources.

For those interested in exploring the intersection of water resource management and climate adaptation, the Graessle-Rockers Lake Dam offers a unique case study in recreational dam construction and maintenance. With its picturesque location and high hazard potential, this dam serves as a reminder of the need for proactive risk assessment and management in safeguarding our vital water infrastructure. As the Graessle-Rockers Lake Dam continues to provide a sanctuary for outdoor enthusiasts, it also serves as a reminder of the delicate balance between water conservation and recreational enjoyment in our changing climate.

Year Completed

1967

Dam Height

31

River Or Stream

TR-OSAGE RIVER

Primary Dam Type

Earth

Surface Area

15

Drainage Area

290

Nid Storage

249

Structural Height

31

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

31
       
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.