O'brien North
O'brien North is an earth dam located in Itasca County, Minnesota, built in 1972. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
About O'brien North
The primary purpose of O'brien North is tailings. Tailings dams contain waste material from mining operations — typically a slurry of finely ground rock left over after valuable minerals have been extracted. These structures require ongoing monitoring because tailings can contain heavy metals and other contaminants. The dam is owned by Us Steel (private). It impounds the O'brien Creek near Pengilly.
The dam stands 58 feet tall and stretches 1,000 feet across, has a maximum storage capacity of 2,550 acre-feet, and collects water from a drainage area of 8 square miles. Completed in 1972, the structure is well into its service life at over 50 years old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. The most recent inspection on record was 10/04/2022.
At 58 feet, this dam is taller than 95% of all dams in the United States.
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Location
| State | Minnesota |
| County | Itasca |
| Nearest City | Pengilly |
| River/Stream | O'brien Creek |
| Coordinates | 47.37959, -93.13380 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 58 ft |
| Dam Height | 49 ft |
| Dam Length | 1,000 ft |
| Year Completed | 1972 (54 years old) |
Storage & Hydraulics
| NID Storage | 2,550 acre-ft |
| Max Storage | 2,550 acre-ft |
| Normal Storage | 1,450 acre-ft |
| Drainage Area | 8 sq mi |
| Max Discharge | 175 cfs |
Ownership & Safety
| Purpose | Tailings |
| Owner | US Steel |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 10/04/2022 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MN00803 |
| Federal ID | MN00803 |
| More Info | State Dam Safety Program |