Chippewa Diversion Dam - Watson Sag Weir Reservoir Report
Last Updated: December 13, 2025
The Chippewa Diversion Dam and Watson Sag Weir, located in Montevideo, Minnesota, are vital flood risk reduction structures managed by the US Army Corps of Engineers.
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Summary
Completed in 1938, the concrete dam stands at 23 feet tall and spans 1900 feet, with a capacity of 150 acre-feet and a maximum discharge of 6200 cubic feet per second. Despite being classified as low hazard dams, a risk assessment conducted in 2009 highlighted concerns for overtopping and intermittent scour downstream of the Chippewa structure.
To mitigate potential risks, the USACE continuously monitors the dam's condition and implements risk management measures to ensure public safety. Regular maintenance and repairs are conducted to uphold the dam's functionality, with a focus on activities that will have the greatest impact on reducing flood risks. Despite the moderate-risk designation, the potential consequences of a breach are minimal, with only minor impacts on downstream water levels during large floods. The Chippewa Diversion Dam and Watson Sag Weir play a crucial role in safeguarding the surrounding area from flooding, showcasing the importance of effective water resource management in addressing climate-related challenges.
Year Completed |
1938 |
Dam Length |
1900 |
Dam Height |
23 |
River Or Stream |
CHIPPEWA RIVER |
Primary Dam Type |
Concrete |
Surface Area |
150 |
Hydraulic Height |
16 |
Drainage Area |
2050 |
Nid Storage |
150 |
Structural Height |
23 |
Hazard Potential |
Low |
Nid Height |
23 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Chippewa River Near Watson
|
423cfs |
Minnesota River Near Lac Qui Parle
|
1240cfs |
Chippewa River Near Milan
|
624cfs |
Lac Qui Parle River Near Lac Qui Parle
|
536cfs |
Minnesota River At Montevideo
|
1810cfs |
Pomme De Terre River At Appleton
|
237cfs |
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.
Chippewa Diversion Dam - Watson Sag Weir