Olson Dam Reservoir Report
Nearby: Herzog Dam Hanks Corner Dam
Last Updated: December 13, 2025
Olson Dam, also known as Tongue River WS Dam T7-1, is a local government-owned structure located in Pembina, North Dakota.
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Summary
Designed by the USDA NRCS and completed in 1957, this earth dam stands at a height of 67 feet and has a structural height of 74 feet, with a length of 990 feet. Its primary purpose is flood risk reduction, with a storage capacity of 1077 acre-feet and a surface area of 7.1 acres.
The dam, regulated by the NDSWC, features an uncontrolled spillway with a width of 250 feet and a single valve outlet gate. Despite its high hazard potential, recent condition assessments have deemed it to be in poor condition as of April 2021. The dam has undergone modifications in 1985 for structural improvements, and its emergency action plan (EAP) status is currently unknown. With a moderate risk assessment rating, it is crucial for authorities to address the dam's deteriorating condition to ensure the safety and integrity of this vital water resource infrastructure.
For water resource and climate enthusiasts, Olson Dam serves as a significant component of the Tongue River watershed, providing essential flood protection for the surrounding area. With its historical significance and ongoing regulatory oversight, this dam exemplifies the critical role that infrastructure plays in managing water resources and mitigating flood risks. As efforts continue to maintain and improve the dam's condition, it is essential for stakeholders to prioritize its safety and resilience in the face of changing climatic conditions and evolving water management challenges.
Years Modified |
1985 - Structural |
Year Completed |
1957 |
Dam Length |
990 |
Dam Height |
67 |
River Or Stream |
TONGUE RIVER-TR |
Primary Dam Type |
Earth |
Surface Area |
7.1 |
Drainage Area |
5.9 |
Nid Storage |
1077 |
Structural Height |
74 |
Outlet Gates |
Valve - 1 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
74 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Tongue River At Akra
|
53cfs |
Little South Pembina River Nr Walhalla
|
5cfs |
Pembina River At Walhalla
|
138cfs |
Pembina River At Neche
|
188cfs |
Park River At Grafton
|
26cfs |
Red River Of The North At Drayton
|
1650cfs |
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.
Olson Dam