Heron Dam Reservoir Report

Last Updated: December 5, 2025

Heron Dam, located in Grand Blanc, Michigan, is a state-owned structure primarily used for recreation along Thread Creek.


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Summary

Completed in 1969, this earth dam stands at a height of 26 feet with a hydraulic height of 23.1 feet and a length of 1025 feet. The dam has a normal storage capacity of 1100 acre-feet and a maximum storage of 1600 acre-feet, providing essential water resources for the area.

With a high hazard potential and fair condition assessment as of October 2018, Heron Dam is regularly inspected by Michigan DEGLE to ensure its safety and compliance with state regulations. The dam's spillway type is uncontrolled, with a width of 3 feet, and the structure poses moderate risk according to the latest risk assessment. Despite its age, Heron Dam continues to serve as a vital recreational spot and water resource in Oakland County, Michigan, attracting visitors from far and wide to enjoy its scenic beauty.

As climate enthusiasts, it is crucial to monitor and support sustainable management practices for dams like Heron Dam to mitigate potential risks and ensure the preservation of water resources for future generations. By staying informed about the dam's condition, regulatory oversight, and emergency preparedness measures, we can contribute to the safeguarding of this essential infrastructure and the surrounding ecosystem in the face of changing environmental conditions.

Year Completed

1969

Dam Length

1025

Dam Height

26

River Or Stream

Thread Creek

Primary Dam Type

Earth

Surface Area

123

Hydraulic Height

23.1

Drainage Area

3.5

Nid Storage

1600

Structural Height

26

Hazard Potential

High

Nid Height

26
       
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.