Mio Reservoir Report
Nearby: Bills Dam Blamer Dam
Last Updated: December 5, 2025
Mio is a captivating hydroelectric dam located on the scenic Au Sable River in Michigan.
°F
°F
mph
Wind
%
Humidity
Summary
Built in 1917, this historic structure stands as a testament to early engineering ingenuity and remains a vital source of renewable energy. With a height of 38 feet and a length of 2120 feet, Mio harnesses the power of the river to generate electricity while also providing recreational opportunities for locals and visitors alike.
Managed by the Federal Energy Regulatory Commission, Mio boasts a controlled spillway and a high hazard potential due to its location and structural design. Although its condition assessment is not available, regular inspections ensure the dam's safety and integrity. The dam's storage capacity of 6061 acre-feet and maximum discharge of 30,880 cubic feet per second highlight its importance in managing water resources and mitigating flood risks in the area.
As a key player in Michigan's water infrastructure, Mio serves as a reminder of the intersection between human innovation and natural resources. Its multi-arch core design and gravity structure blend seamlessly into the surrounding landscape, demonstrating how sustainable energy production can coexist with environmental conservation. For water resource and climate enthusiasts, Mio represents a harmonious balance between human needs and ecological stewardship, making it a symbol of resilience and progress in the face of climate challenges.
Year Completed |
1917 |
Dam Length |
2120 |
Dam Height |
38 |
River Or Stream |
Au Sable River |
Primary Dam Type |
Gravity |
Surface Area |
661 |
Hydraulic Height |
29.5 |
Drainage Area |
1100 |
Nid Storage |
6061 |
Structural Height |
36 |
Outlet Gates |
Other Controlled - 2, Tainter (radial) - 1 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
38 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Au Sable River At Mio
|
665cfs |
Au Sable River Near Red Oak
|
609cfs |
Au Sable River Near Mc Kinley
|
965cfs |
South Branch Au Sable River Near Luzerne
|
130cfs |
Au Sable River Near Curtisville
|
838cfs |
Au Sable River Near Au Sable
|
883cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Mio Pond State Forest Campground and Group Camp
Au Sable Loop Campground and Day Use Area
River Dune Campground
Meadow Springs Campground
Cathedral Pines Campground
Wagner Lake Campground
Mio