Thoreson-Monson Dam Reservoir Report

Last Updated: December 13, 2025

Thoreson-Monson Dam, located in Barnes County, North Dakota, was completed in 1966 by the USDA NRCS for the primary purpose of recreation.


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Summary

This private-owned Earth dam stands at 40 feet tall and stretches 296 feet in length, offering a storage capacity of 92 acre-feet with a normal storage level of 70 acre-feet. Situated on the Sheyenne River, this dam serves as a popular spot for water resource and climate enthusiasts to enjoy various recreational activities such as fishing, boating, and wildlife observation.

Despite being categorized as having a low hazard potential, the dam has a moderate risk level due to its location and size. Thoreson-Monson Dam is regulated by the NDSWC and undergoes state permitting, inspection, and enforcement to ensure its structural integrity and compliance with safety standards. The dam features an uncontrolled spillway, with a width of 96 feet, and has no outlet gates. While the dam's condition is currently not rated, it remains a vital asset for water management in the region and a key site for outdoor recreation enthusiasts to appreciate the beauty of the Sheyenne River.

Year Completed

1966

Dam Length

296

Dam Height

35

River Or Stream

SHEYENNE RIVER-TR

Primary Dam Type

Earth

Surface Area

6.9

Drainage Area

1.78

Nid Storage

92

Structural Height

40

Outlet Gates

None

Hazard Potential

Low

Foundations

Soil

Nid Height

40
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.