Fish Lake Reservoir Report

Reservoir Report

Montana

Nearby: Upper Bear Dam Lower Twin Lakes

Last Updated: December 15, 2025

Fish Lake, located in Ravalli County, Montana, is a federal-owned water resource managed by the USDA Forest Service.

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Summary

Built in 1927, this Earth dam serves multiple purposes including fire protection, stock watering, and as a small fish pond for recreational activities. With a dam height of 26 feet and a storage capacity of 400 acre-feet, Fish Lake covers a surface area of 6 acres and is fed by the South Fork Lost Horse Creek.

Despite being categorized as having a low hazard potential, Fish Lake's condition assessment remains unrated as of the last inspection in March 2017. The dam features an uncontrolled spillway and outlet gates, with a moderate risk assessment rating. While no emergency action plan has been reported, the site's risk management measures and inundation maps status are also unknown. With its picturesque location and diverse purposes, Fish Lake stands as a vital water resource in the region, attracting enthusiasts interested in water conservation and climate-related activities.

Surrounded by the stunning wilderness of Hamilton, Montana, Fish Lake remains a focal point for water resource and climate enthusiasts. As a key component of the region's ecosystem, the lake not only serves practical purposes such as fire protection and stock watering but also offers recreational opportunities for visitors. Given its historical significance dating back to 1927 and the Forest Service's role in its maintenance, Fish Lake continues to be a captivating destination for those interested in the intersection of water management, climate resilience, and environmental conservation.

Year Completed	1927
Dam Length	287
Dam Height	26
River Or Stream	SOUTH FORK LOST HORSE CREEK
Primary Dam Type	Earth
Surface Area	6
Hydraulic Height	6
Drainage Area	1
Nid Storage	400
Structural Height	14
Outlet Gates	Uncontrolled
Hazard Potential	Low
Nid Height	26

Explore Interactive Map

FISH LAKE

Reservoir Report • Water Levels • Weather Forecast

December 15, 2025

Year_Completed	1927
Dam_Length	287
Dam_Height	26
River_Or_Stream	SOUTH FORK LOST HORSE CREEK
Primary_Dam_Type	Earth
Surface_Area	6
Hydraulic_Height	6
Drainage_Area	1
Nid_Storage	400
Structural_Height	14
Outlet_Gates	Uncontrolled
Hazard_Potential	Low
Nid_Height	26

Seasonal Comparison

Weather Forecast

Nearby Streamflow Levels

Bitterroot River Near Darby Mt 627.0cfs	627cfs
West Fork Bitterroot River Nr Conner Mt 54.3cfs	54cfs
Bitterroot River At Bell Crossing Nr Victor Mt 670.0cfs	670cfs
Middle Fork Rock Cr Nr Philipsburg Mt 63.5cfs	64cfs
Selway River Nr Lowell Id 5630.0cfs	5630cfs
Salmon River Nr Shoup Id 1670.0cfs	1670cfs

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.