Henson Dam Reservoir Report

Last Updated: December 5, 2025

Henson Dam, located in Marathon Township, Michigan, is a privately owned earth dam built in 1999 primarily for recreational purposes.


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Summary

Standing at a height of 27 feet with a hydraulic height of 10.5 feet, this dam boasts a storage capacity of 800 acre-feet and covers a surface area of 66 acres. It is regulated by the Michigan Department of Environment, Great Lakes, and Energy (DEGLE) and undergoes regular inspections to ensure its structural integrity.

Despite its low hazard potential and satisfactory condition assessment, Henson Dam poses a moderate risk due to its location in Lapeer County, Michigan. The dam's uncontrolled spillway, with a width of 2 feet, contributes to its risk assessment rating of 3 out of 5. The dam has a drainage area of 0.15 square miles and is a tributary to Hemingway Lake. With a history of regular inspections and adherence to regulatory guidelines, Henson Dam remains a vital resource for both water management and climate enthusiasts in the region.

Overall, Henson Dam serves as a crucial recreational resource in the area, offering opportunities for outdoor activities and water-based recreation. Its stable condition, regulated oversight, and moderate risk assessment underscore its importance in managing water resources and adapting to climate challenges in a sustainable manner. As a privately owned structure, Henson Dam stands as a testament to the collaboration between private entities and state agencies in ensuring the safety and functionality of essential water infrastructure.

Year Completed

1999

Dam Length

2700

Dam Height

27

River Or Stream

Tributary to Hemingway Lake

Primary Dam Type

Earth

Surface Area

66

Hydraulic Height

10.5

Drainage Area

0.15

Nid Storage

800

Structural Height

27

Hazard Potential

Low

Nid Height

27
       
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.
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Area Campgrounds