Hassett #2 Reservoir Report

Last Updated: December 6, 2025

Hassett #2 is a privately owned earth dam located in Petroleum County, Montana, along the TR-Flatwillow Creek.


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Summary

Built in 1959 by the USDA NRCS, the dam serves multiple purposes including fire protection, stock water, and a small fish pond. With a dam height of 15 feet and a storage capacity of 74 acre-feet, it plays a crucial role in water resource management in the area.

Despite being classified as having a low hazard potential, Hassett #2 is recognized as a moderate risk structure with a risk assessment rating of 3. The dam is regulated by the Montana Department of Natural Resources and Conservation (DNRC) and undergoes regular inspections, enforcement, and permitting to ensure its safety and functionality. With a spillway width of 100 feet and a maximum discharge capacity of 500 cubic feet per second, the dam is designed to handle potential flooding events.

For water resource and climate enthusiasts, Hassett #2 serves as a notable example of how earth dams can support various water management needs while also posing certain risks that necessitate ongoing monitoring and maintenance. The dam's location in a rural area highlights the importance of sustainable water infrastructure in supporting agricultural activities and wildlife habitats in Montana.

Year Completed

1959

Dam Length

300

Dam Height

15

River Or Stream

TR-FLATWILLOW CREEK

Primary Dam Type

Earth

Hydraulic Height

15

Drainage Area

0.94

Nid Storage

74

Hazard Potential

Low

Nid Height

15
       
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.