Knott Detention Reservoir Report
Last Updated: December 13, 2025
Knott Detention, also known as the Arlen Knott Detention Dam, is a privately owned structure located in Sanborn, Minnesota.
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Summary
Built in 1977 by the USDA NRCS, this earth dam stands at a height of 32 feet and stretches 570 feet in length along the Cottonwood River. Its primary purpose is flood risk reduction, with a storage capacity of 261 acre-feet and a maximum discharge rate of 686 cubic feet per second.
Managed by the Minnesota Department of Natural Resources, Knott Detention is regulated, permitted, inspected, and enforced by state agencies to ensure its structural integrity and public safety. Despite its low hazard potential and satisfactory condition assessment, the dam undergoes regular inspections every eight years to monitor its performance. The surrounding area, with a drainage area of 2 square miles, benefits from the dam's flood protection measures, with a normal storage capacity of 63 acre-feet and a surface area of 6 acres.
Overall, Knott Detention plays a crucial role in mitigating flood risks in the Redwood County region of Minnesota. With its efficient design and operational protocols, this structure provides a valuable resource for water resource and climate enthusiasts interested in sustainable flood management practices.
Year Completed |
1977 |
Dam Length |
570 |
Dam Height |
32 |
River Or Stream |
COTTONWOOD RIVER-TR |
Primary Dam Type |
Earth |
Surface Area |
6 |
Drainage Area |
2 |
Nid Storage |
261 |
Structural Height |
44 |
Outlet Gates |
Uncontrolled |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
44 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Redwood River Near Redwood Falls
|
53cfs |
Redwood River Near Marshall
|
0cfs |
Minnesota River At Morton
|
1750cfs |
Yellow Medicine River Near Granite Falls
|
133cfs |
Minnesota River At Montevideo
|
1810cfs |
Minnesota River At New Ulm
|
1130cfs |
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.
Knott Detention