North Twin
North Twin is an earth dam located in Penobscot County, Maine, built in 1934. It carries a High hazard potential classification and has a satisfactory condition assessment.
About North Twin
The primary purpose of North Twin is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. It impounds the West Branch Penobscot River near Millinocket.
The dam stands 35 feet tall and stretches 1,051 feet across, creates a reservoir covering 17,790 acres, has a maximum storage capacity of 346,000 acre-feet, and collects water from a drainage area of 1,877 square miles. Completed in 1934, the structure is well-established, with more than 75 years of service.
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 satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 08/10/2022.
At 35 feet, this dam is taller than 82% of dams nationwide.
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 Maine 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 | Maine |
| County | Penobscot |
| Nearest City | Millinocket |
| River/Stream | West Branch Penobscot River |
| Coordinates | 45.63486, -68.78094 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 35 ft |
| Dam Height | 35 ft |
| Dam Length | 1,051 ft |
| Year Completed | 1934 (92 years old) |
Storage & Hydraulics
| NID Storage | 346,000 acre-ft |
| Max Storage | 346,000 acre-ft |
| Normal Storage | 346,000 acre-ft |
| Surface Area | 17,790 acres |
| Drainage Area | 1,877 sq mi |
| Max Discharge | 72,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner Type | Not Listed |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/10/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | ME00203 |
| Federal ID | ME00203 |
| More Info | State Dam Safety Program |