O'Brien North Reservoir Report
Nearby: Perry-Wyman Tailings Reservoir No. 2
Last Updated: December 13, 2025
O'Brien North, also known as Reservoir 4, is a private-owned dam located in Itasca County, Minnesota.
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Summary
Completed in 1972, this earth dam stands at 49 feet high and serves primarily for tailings purposes related to mining activities in the area. With a storage capacity of 2550 acre-feet and a drainage area of 8 square miles, O'Brien North plays a crucial role in managing water resources in the region.
Managed by the Minnesota Department of Natural Resources, O'Brien North is regulated, inspected, and enforced by state agencies to ensure its safety and integrity. The dam has a significant hazard potential and has been assessed to be in fair condition as of August 2015. Its last inspection in June 2018 indicated that it meets regulatory guidelines, but further risk assessments and emergency preparedness measures may need to be undertaken to enhance its resilience to potential disasters.
Situated on O'Brien Creek, O'Brien North is a key component of the water infrastructure in the area, providing vital flood control and water storage capabilities. As climate change continues to impact the region, ensuring the safety and effectiveness of dams like O'Brien North becomes increasingly important for water resource and climate enthusiasts alike.
Year Completed |
1972 |
Dam Length |
1000 |
Dam Height |
49 |
River Or Stream |
O'BRIEN CREEK |
Primary Dam Type |
Earth |
Drainage Area |
8 |
Nid Storage |
2550 |
Structural Height |
58 |
Hazard Potential |
Significant |
Foundations |
Unlisted/Unknown |
Nid Height |
58 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Prairie River Near Taconite
|
63cfs |
Mississippi River At Grand Rapids
|
633cfs |
St. Louis River At Scanlon
|
693cfs |
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.
O'Brien North
O'Brien Reservoir