Rush Lake Level Control Structure Reservoir Report

Last Updated: December 5, 2025

The Rush Lake Level Control Structure in Michigan is a privately owned dam that serves primarily for recreation purposes.


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Summary

Completed in 1956, this Earth dam stands at a height of 19 feet and has a storage capacity of 5025 acre-feet, with a normal storage capacity of 2250 acre-feet. Located on the North Branch Thunder Bay River, this controlled spillway structure has a spillway width of 30 feet and a maximum discharge of 106 cubic feet per second, helping to manage water levels in Rush Lake.

With a low hazard potential and a very high risk assessment rating, the Rush Lake Level Control Structure is regulated by the Michigan Department of Environment, Great Lakes, and Energy (EGLE). Regular state inspections and enforcement ensure the safety and functionality of the dam, although its condition is currently not rated. The structure's emergency action plan status and risk management measures are not fully documented, indicating a potential area for improvement in preparedness for any unforeseen events. For water resource and climate enthusiasts, the Rush Lake Level Control Structure provides an interesting case study in dam management and regulation within the state of Michigan.

Year Completed

1956

Dam Length

350

Dam Height

19

River Or Stream

N Br Thunder Bay River

Primary Dam Type

Earth

Surface Area

355

Hydraulic Height

14

Nid Storage

5025

Structural Height

19

Hazard Potential

Low

Nid Height

19
       
Seasonal Comparison

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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.