Ivy #3 Reservoir Report
Last Updated: December 5, 2025
Ivy #3 is a privately owned earth dam located in Musselshell, Montana, near the city of Mosby.
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Summary
Built in 1974 by the USDA NRCS, this dam serves multiple purposes including fire protection, stock watering, and small fish pond creation. With a height of 20 feet and a storage capacity of 340 acre-feet, Ivy #3 is situated on the Little Wall Creek with a drainage area of 6.25 square miles.
Managed by the Montana Department of Natural Resources and Conservation (DNRC), Ivy #3 has a low hazard potential and has not been rated for its condition. Despite its age, the dam is regularly inspected and maintained, with state permitting, inspection, and enforcement measures in place to ensure its safety and functionality. The dam also has a spillway width of 100 feet to manage maximum discharge of up to 1100 cubic feet per second, providing crucial flood protection for the surrounding area.
Located in Congressional District 00, Montana, Ivy #3 plays a vital role in water resource management in the region. With its primary purpose being fire protection and irrigation, the dam contributes to the sustainability of the local ecosystem and supports agricultural activities in the area. As a key infrastructure for water storage and management, Ivy #3 serves as a testament to the importance of proper dam construction and maintenance in ensuring water security and climate resilience.
Year Completed |
1974 |
Dam Length |
924 |
Dam Height |
20 |
River Or Stream |
Little Wall Creek |
Primary Dam Type |
Earth |
Hydraulic Height |
16.1 |
Drainage Area |
6.25 |
Nid Storage |
340 |
Hazard Potential |
Low |
Nid Height |
20 |
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.
Ivy #3