Bass Lake Reservoir Report

Last Updated: December 5, 2025

Bass Lake, also known as Bass Creek Reservoir, is a private water resource located in Ravalli, Montana, near the city of Florence.


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Summary

The lake was completed in 1887 and serves multiple purposes including flood risk reduction, hydroelectric power generation, irrigation, navigation, and recreation. With a dam height of 35 feet and a storage capacity of 3,900 acre-feet, Bass Lake covers a surface area of 93 acres and has a drainage area of 5 square miles.

Managed by the Montana Department of Natural Resources and Conservation (DNRC), Bass Lake has a spillway width of 23 feet and a maximum discharge of 405 cubic feet per second. The lake has a high hazard potential and a moderate risk assessment rating. Although the condition assessment is not rated, the lake's emergency action plan (EAP) status is unknown. The lake's risk management measures and inundation maps preparation status are also not specified, indicating a need for further evaluation and planning to ensure the safety and sustainability of this important water resource in the region.

Overall, Bass Lake is a vital water infrastructure in Montana that plays a significant role in flood control, irrigation, and recreational activities. With its historical significance dating back to the late 19th century, the lake continues to be a valuable asset to the community. As water resource and climate enthusiasts, it is important to monitor and evaluate the safety and sustainability of Bass Lake to ensure its continued functionality and benefit to the surrounding area.

Year Completed

1887

Dam Length

450

Dam Height

35

River Or Stream

BASS CREEK

Primary Dam Type

Earth

Surface Area

93

Hydraulic Height

35

Drainage Area

5

Nid Storage

3900

Structural Height

35

Hazard Potential

High

Nid Height

35
       
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.