Sonny #1 Reservoir Report
Nearby: Jim Bob #1 Murnions (Jim)
Last Updated: December 6, 2025
Sonny #1 is a privately-owned earth dam located on Sonny Coulee in Garfield, Montana.
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Summary
Completed in 1950, this dam serves multiple purposes including fire protection, stock, and a small fish pond. With a height of 14 feet and a length of 400 feet, Sonny #1 has a storage capacity of 72 acre-feet and a maximum discharge capacity. Despite being categorized as a low hazard potential structure, the dam's condition assessment is currently listed as "Not Rated".
Managed by the Montana Department of Natural Resources and Conservation (DNRC), Sonny #1 is regulated, permitted, inspected, and enforced by the state agency. Located in Congressional District 00, Montana, this dam plays a crucial role in water resource management in the region. As a key feature in the local landscape, Sonny #1 provides essential water storage for fire protection and livestock while also supporting recreational activities like fishing. With its historical significance and ongoing maintenance, Sonny #1 stands as a testament to sustainable water resource management in Montana.
Year Completed |
1950 |
Dam Length |
400 |
Dam Height |
14 |
River Or Stream |
SONNY COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
14 |
Nid Storage |
72 |
Hazard Potential |
Low |
Nid Height |
14 |
Seasonal Comparison
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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.
Sonny #1