Tioga Lake Auxiliary is a concrete dam located in Mono County, California, built in 1928. It carries a High hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 19 ft19 ft tall and 50 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Tioga Lake Auxiliary
The primary purpose of Tioga Lake Auxiliary is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by Southern California Edison Company (private). It impounds the Glacier Creek near Lee Vining.
The dam stands 19 feet tall and stretches 50 feet across, creates a reservoir covering 73 acres, and has a maximum storage capacity of 1,254 acre-feet. Completed in 1928, the structure is well-established, with more than 75 years of service.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 08/19/2025.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The California dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | California |
| County | Mono |
| Nearest City | Lee Vining |
| River/Stream | Glacier Creek |
| Coordinates | 37.92860, -119.25290 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 19 ft |
| Dam Height | 19 ft |
| Dam Length | 50 ft |
| Year Completed | 1928 (98 years old) |
Storage & Hydraulics
| NID Storage | 1,254 acre-ft |
| Max Storage | 1,254 acre-ft |
| Normal Storage | 1,254 acre-ft |
| Surface Area | 73 acres |
| Max Discharge | 690 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Southern California Edison Company |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/19/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00456 |
| Federal ID | CA00456S001 |
| More Info | State Dam Safety Program |