Green Oak Lake Dam Reservoir Report

Last Updated: December 5, 2025

Green Oak Lake Dam, located in Washtenaw County, Michigan, is a privately owned structure with a primary purpose of recreation.


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Summary

Completed in 1960, this Earth-type dam stands at a height of 20 feet and stretches 425 feet in length. The dam has a storage capacity of 200 acre-feet and a normal storage level of 80 acre-feet, serving as a popular spot for outdoor activities in the area.

Managed by the Michigan Department of Environment, Great Lakes, and Energy (DEGLE), the Green Oak Lake Dam is regulated, permitted, inspected, and enforced by the state. The dam, which is situated on a tributary to the Huron River, has a controlled spillway with a width of 6 feet and a maximum discharge capacity of 625 cubic feet per second. Despite being classified as having a low hazard potential, the dam's risk assessment is marked as very high, indicating the importance of ongoing monitoring and maintenance to ensure its safety and functionality.

With a satisfactory condition assessment as of November 2017, the Green Oak Lake Dam provides a serene recreational environment for visitors while also playing a crucial role in water resource management in the region. As climate change continues to impact water resources, the upkeep and regulation of dams like Green Oak Lake Dam are essential in safeguarding communities and ecosystems against potential risks and disruptions.

Year Completed

1960

Dam Length

425

Dam Height

20

River Or Stream

Tributary to Huron River

Primary Dam Type

Earth

Surface Area

19

Hydraulic Height

20

Drainage Area

7.6

Nid Storage

200

Structural Height

20

Hazard Potential

Low

Nid Height

20
       
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.