Little Black River Structure D Reservoir Report

Last Updated: December 5, 2025

Little Black River Structure D, also known as the High School Structure, is a vital flood risk reduction infrastructure located in Cheboygan, Michigan.


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Summary

Managed by the local government, this earth dam stands at a height of 25 feet and boasts a hydraulic height of 19 feet. Built in 1964 by the USDA NRCS, it plays a crucial role in protecting the surrounding area from potential flooding by the South Br Little Black River.

With a storage capacity of 313 acre-feet and a spillway width of 504 feet, Little Black River Structure D is designed to handle high hazard potential situations. Despite its age, the dam's condition assessment in 2017 deemed it satisfactory, showcasing its reliability and effectiveness in mitigating flood risks. As a regulated structure under the oversight of the Michigan DEGLE, this dam undergoes regular inspections and maintenance to ensure its continued functionality and safety for the community it serves. For water resource and climate enthusiasts, Little Black River Structure D serves as a prime example of effective flood risk reduction infrastructure in action.

Year Completed

1964

Dam Length

480

Dam Height

25

River Or Stream

South Br Little Black River

Primary Dam Type

Earth

Hydraulic Height

19

Drainage Area

3.9

Nid Storage

313

Structural Height

25

Outlet Gates

None

Hazard Potential

High

Foundations

Soil

Nid Height

25
       
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.