Portage Plant Dam
Portage Plant Dam is an earth dam located in St. Joseph County, Michigan, built in 1922. It carries a High hazard potential classification and has a poor condition assessment.
About Portage Plant Dam
The primary purpose of Portage Plant Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Portage Power Company (private). It impounds the Portage River near Three Rivers.
The dam stands 19 feet tall and stretches 1,116 feet across, creates a reservoir covering 81 acres, has a maximum storage capacity of 1,300 acre-feet, and collects water from a drainage area of 192 square miles. Completed in 1922, the structure is over a century old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. An emergency action plan is in place for this dam. The most recent inspection on record was 12/02/2021.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Michigan dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Michigan |
| County | St. Joseph |
| Nearest City | Three Rivers |
| River/Stream | Portage River |
| Coordinates | 41.95667, -85.62500 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 19 ft |
| Dam Height | 19 ft |
| Dam Length | 1,116 ft |
| Year Completed | 1922 (104 years old) |
Storage & Hydraulics
| NID Storage | 1,300 acre-ft |
| Max Storage | 1,300 acre-ft |
| Normal Storage | 900 acre-ft |
| Surface Area | 81 acres |
| Drainage Area | 192 sq mi |
| Max Discharge | 7,734 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Portage Power Company |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Poor |
| Last Inspection | 12/02/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MI00374 |
| Federal ID | MI00374 |
| More Info | State Dam Safety Program |