Tioga Lake Auxiliary Reservoir Report

Last Updated: December 5, 2025

Tioga Lake Auxiliary, located in Lee Vining, California, is a private hydroelectric dam constructed in 1928 with a primary purpose of generating electricity.


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Summary

The dam stands at a height of 19 feet and has a storage capacity of 1254 acre-feet, providing necessary water resources for the surrounding area. With a surface area of 73 acres and a maximum discharge of 690 cubic feet per second, the dam plays a crucial role in regulating water flow in Glacier Creek.

Managed by the Federal Energy Regulatory Commission, the Tioga Lake Auxiliary dam has a high hazard potential and is subject to regular state inspections and enforcement to ensure its safety and structural integrity. Although the condition assessment is not currently available, emergency action plans are in place, with the last revision completed in December 2020. Despite moderate risk assessments, the dam continues to serve as a vital resource for both hydroelectric power generation and recreational activities, highlighting the intersection of water resource management and climate resilience in the region.

Year Completed

1928

Dam Length

50

Dam Height

19

River Or Stream

Glacier Creek

Primary Dam Type

Concrete

Surface Area

73

Nid Storage

1254

Structural Height

19

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

19
       
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.