Upper Long Lake Dam Reservoir Report

Last Updated: December 5, 2025

Upper Long Lake Dam, located in Millville, Michigan, is a state-owned earth dam on the Abbott Drain.


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Summary

Built in 1992, this dam stands at a height of 7 feet with a hydraulic height of 5.3 feet, serving as a vital structure for water resource management in the region. With a normal storage capacity of 300 acre-feet and a maximum discharge of 310 cubic feet per second, the dam plays a crucial role in regulating water flow and preventing flooding in the area.

Despite its low hazard potential and satisfactory condition assessment, Upper Long Lake Dam is subject to periodic inspections every five years to ensure its structural integrity and operational efficiency. The dam's spillway, with a width of 26 feet, is uncontrolled, allowing for the safe release of excess water during peak flow periods. With a moderate risk assessment rating of 3, measures for risk management and emergency preparedness are continuously evaluated to mitigate any potential threats to the dam and surrounding communities.

Upper Long Lake Dam, nestled in the scenic landscape of Lapeer County, Michigan, stands as a testament to the importance of sustainable water resource management and climate resilience. As a key component of the region's infrastructure, this dam serves not only as a barrier against flooding but also as a symbol of the ongoing efforts to balance water conservation with environmental protection. Its role in safeguarding the local ecosystem and supporting the community's water needs underscores the interconnectedness of water resources and climate dynamics in shaping our shared future.

Year Completed

1992

Dam Length

660

Dam Height

7

River Or Stream

Abbott Drain

Primary Dam Type

Earth

Surface Area

215

Hydraulic Height

5.3

Drainage Area

2.9

Nid Storage

1100

Structural Height

7

Hazard Potential

Low

Nid Height

7
       
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.