Larson Dam; John M Reservoir Report
Last Updated: December 6, 2025
Larson Dam, also known as John M.
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Summary
Larson Dam, is a private structure located in Adams County, North Dakota. Built in 1950 by the USFWS, this earth dam serves as a fish and wildlife pond with a storage capacity of 200 acre-feet. The dam stands at a height of 12 feet and has a length of 1000 feet, creating a surface area of 25 acres.
The dam is regulated by the North Dakota State Water Commission, with state permitting, inspection, and enforcement in place. It has a spillway width of 470 feet and is classified as having a low hazard potential. In 1991, the dam underwent structural modifications to ensure its continued safety and functionality. With a moderate risk assessment rating, the dam is closely monitored to mitigate any potential risks and ensure the protection of surrounding areas.
Located on Cedar Creek-TR, Larson Dam plays a crucial role in the local ecosystem by providing a habitat for fish and wildlife. Its construction and management reflect a commitment to conservation efforts in North Dakota. With its unique design and purpose, Larson Dam stands as a testament to the importance of water resource management and climate resilience in the region.
Years Modified |
1991 - Structural |
Year Completed |
1950 |
Dam Length |
1000 |
Dam Height |
12 |
River Or Stream |
CEDAR CREEK-TR |
Primary Dam Type |
Earth |
Surface Area |
25 |
Drainage Area |
5.66 |
Nid Storage |
200 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
12 |
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.
Larson Dam; John M