Geddes Dam Reservoir Report

Last Updated: December 5, 2025

Geddes Dam, located in Ypsilanti, Michigan, is a vital structure on the Huron River that serves as a popular recreational spot for locals and visitors alike.


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Summary

Built in 1920, this earth dam stands at 28 feet high and spans 274 feet in length, with a maximum storage capacity of 3,100 acre-feet and a normal storage capacity of 4,250 acre-feet. The dam plays a crucial role in regulating water flow, with a maximum discharge capacity of 14,400 cubic feet per second and a controlled spillway width of 84 feet.

Managed by the local government and regulated by the Michigan Department of Environment, Great Lakes, and Energy (DEGLE), Geddes Dam is inspected regularly to ensure its structural integrity and safety. Despite being classified as a high hazard potential structure, the dam is currently assessed to be in fair condition. With a risk assessment rating of very high, measures are in place to manage potential risks and emergencies effectively. Given its significance in water resource management and recreation, Geddes Dam continues to be a key landmark in the region, attracting outdoor enthusiasts and nature lovers.

Overall, Geddes Dam stands as a testament to effective water management and recreational development in Washtenaw County. With its rich history and functional design, the dam remains a vital component of the local landscape, offering both leisure and safety benefits to the community. As efforts continue to maintain and monitor its condition, Geddes Dam serves as a beacon of resilience and sustainability in the face of changing climate conditions and environmental challenges.

Year Completed

1920

Dam Length

274

Dam Height

28

River Or Stream

Huron River

Primary Dam Type

Earth

Surface Area

261

Hydraulic Height

24.5

Drainage Area

765

Nid Storage

4250

Structural Height

28

Hazard Potential

High

Nid Height

28
       
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.