Hart Lake Reservoir Report

Last Updated: December 5, 2025

Hart Lake in Michigan is a captivating water resource site that serves as a hydroelectric dam on the South Branch Pentwater River.


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Summary

This Earth dam, completed in 1927, stands at a height of 31 feet and stretches 580 feet in length, providing a storage capacity of 3600 acre-feet. With a surface area of 240 acres and a controlled spillway width of 56 feet, Hart Lake is a key player in managing water resources in Oceana County.

Managed by the Federal Energy Regulatory Commission, Hart Lake has a low hazard potential but is associated with a very high risk due to its critical infrastructure status. The dam relies on three outlet gates for water control, ensuring the safety of the surrounding area. Despite its age, Hart Lake has experienced regular inspections and has an Emergency Action Plan in place, demonstrating a commitment to the safety and maintenance of this vital water resource site.

For water resource and climate enthusiasts, Hart Lake represents a blend of history, engineering, and environmental stewardship. Its role as a hydroelectric facility underscores the importance of sustainable energy production, while its location in a picturesque setting near Pentwater adds to its allure. With a rich history dating back to the early 20th century, Hart Lake continues to be a significant player in water management efforts in Michigan, showcasing the intersection of human ingenuity and natural resources in the face of climate challenges.

Year Completed

1927

Dam Length

580

Dam Height

31

River Or Stream

South Branch Pentwater

Primary Dam Type

Earth

Surface Area

240

Nid Storage

3600

Outlet Gates

None - 1, Slide (sluice gate) - 2

Hazard Potential

Low

Nid Height

31
       
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.