Pool No. 21 Reservoir Report
Nearby: Pool No. 23 Pool No. 22
Last Updated: December 13, 2025
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Summary
21, located in Thief River Falls, Minnesota, is a federally owned earth dam completed in 1971 with a primary purpose of "Other." This dam stands at a height of 8 feet and spans a length of 1300 feet, providing a maximum storage capacity of 5370 acre-feet. The dam is situated on the Mud River and is under the jurisdiction of the Omaha District of the US Army Corps of Engineers.
Despite its low hazard potential, Pool No. 21 plays a crucial role in managing water resources in the area. With a normal storage capacity of 2100 acre-feet and a maximum discharge capability of 1400 cubic feet per second, this dam helps regulate water flow and mitigate flooding risks in the region. Although not currently rated for condition assessment, regular inspections are conducted every 8 years to ensure the safety and functionality of the structure.
Water resource and climate enthusiasts interested in the infrastructure that supports sustainable water management practices will find Pool No. 21 a fascinating feat of engineering. This structure not only serves as a vital component of the local water management system but also reflects the importance of maintaining and monitoring such critical infrastructure to ensure the resilience of water resources in the face of changing climate conditions.
Year Completed |
1971 |
Dam Length |
1300 |
Dam Height |
8 |
River Or Stream |
MUD RIVER |
Primary Dam Type |
Earth |
Nid Storage |
5370 |
Structural Height |
8 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
8 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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.
Pool No. 21