Granite Lake Reservoir Report

Last Updated: December 21, 2025

Granite Lake, also known as Upper Granite Lake, is a privately owned reservoir located in McCall, Idaho.


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Summary

The dam was completed in 1949 for irrigation purposes, with a primary dam type of earth and core types of stone. The dam stands at a height of 24.8 feet with a hydraulic height of 20.5 feet, creating a storage capacity of 2900 acre-feet and covering a surface area of 195 acres. The reservoir is fed by Lake Creek East Fork and Fisher Creek, with a drainage area of 2.19 square miles.

The dam at Granite Lake is regulated by the Idaho Department of Water Resources, with state permitting, inspection, and enforcement in place. The spillway, which is uncontrolled, has a width of 10 feet and a maximum discharge capacity of 73 cubic feet per second. The dam has been assessed to have a significant hazard potential and is currently in fair condition as of the last inspection in July 2018. The risk assessment for Granite Lake is moderate, with a risk management plan in place to address any potential issues.

Located in the beautiful Valley County, Idaho, Granite Lake offers a vital water resource for irrigation in the region. As a key component of the local water infrastructure, this reservoir plays a crucial role in supporting agricultural activities in the area. With its picturesque setting and important function, Granite Lake serves as a fascinating site for water resource and climate enthusiasts to explore and study.

Year Completed

1949

Dam Length

1460

Dam Height

24.8

River Or Stream

LAKE CREEK EAST FORK FISHER CREEK

Surface Area

195

Hydraulic Height

20.5

Drainage Area

2.19

Nid Storage

2900

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

25
       
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.