Mix Reservoir Report

Last Updated: December 5, 2025

Mix, also known as the State Street Dam, is a private hydroelectric structure located on the Grand River in Eaton Rapids, Michigan.


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Summary

Built in 1910, this gravity dam stands at 15 feet tall and spans 188 feet in length. With a normal storage capacity of 180 acre-feet and a maximum discharge of 3,670 cubic feet per second, Mix plays a vital role in harnessing the power of water to generate electricity.

Managed by the Federal Energy Regulatory Commission, Mix has a low hazard potential and is deemed to have a moderate risk level. The dam features an uncontrolled spillway with a width of 20 feet and is equipped with slide and vertical lift outlet gates for water flow regulation. While its condition assessment is currently not available, Mix undergoes inspections every three years to ensure its structural integrity and operational safety.

Water resource and climate enthusiasts will find Mix to be a fascinating example of historical hydroelectric infrastructure in Michigan. Its multi-arch design, soil foundation, and strategic location on the Grand River contribute to its role in renewable energy production. As efforts continue to monitor and maintain this important structure, Mix stands as a symbol of sustainable energy generation and the intersection of water resources and climate resilience.

Year Completed

1910

Dam Length

188

Dam Height

7

River Or Stream

Grand River

Primary Dam Type

Gravity

Surface Area

80

Hydraulic Height

9

Drainage Area

654

Nid Storage

500

Structural Height

15

Outlet Gates

Slide (sluice gate) - 3, Vertical Lift - 1

Hazard Potential

Low

Foundations

Soil

Nid Height

15
       
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.