Henrys Lake Nr Lake Id Reservoir Report

Last Updated: December 5, 2025

Henry's Lake is a natural lake located in Idaho, USA.


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Summary

The lake has a long history, first known to be inhabited by Native Americans. Today, it is a popular destination for recreational activities such as fishing, boating, and camping. The lake is fed by several small streams, including Targhee Creek, Howard Creek, and Henrys Fork, and its outflow is Henrys Fork. The lake is also part of the Henrys Fork Watershed, which provides water for agriculture and industry in the region. Snowpack in the surrounding mountains is a significant source of water for the lake, and it also receives some surface flow from nearby creeks. The lake is known for its healthy populations of trout, including Yellowstone cutthroat, rainbow, and brook trout.

Reservoir Details

Gage Height, Ft 24hr Change 0.41%
Percent of Normal None%
Minimum 6.86 ft
2022-12-22
Maximum 17.17 ft
2023-06-14
Average 15 ft
Dam_Height 25.2
Hydraulic_Height 22.5
Drainage_Area 93.4
Year_Completed 1923
Nid_Storage 58700
River_Or_Stream HENRYS FORK SNAKE RIVER
Foundations Rock, Soil
Surface_Area 6050
Hazard_Potential High
Outlet_Gates Slide (sluice gate)
Dam_Length 408
Nid_Height 25
       
Seasonal Comparison
Reservoir Storage, Acre-Ft Levels
Gage Height, Ft Levels

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.