Lower Peak Lake Auxiliary
Lower Peak Lake Auxiliary is an earth dam located in Placer County, California, built in 1860. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Lower Peak Lake Auxiliary
The primary purpose of Lower Peak 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 Pacific Gas And Electric Company (private). It impounds the South Yuba River - Tr near Washington.
The dam stands 7 feet tall and stretches 410 feet across, creates a reservoir covering 33 acres, has a maximum storage capacity of 484 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1860, the structure is one of the older dams in the region, with over a century and a half 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 06/28/2022.
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 | Placer |
| Nearest City | Washington |
| River/Stream | South Yuba River - Tr |
| Coordinates | 39.30410, -120.43860 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 7 ft |
| Dam Height | 7 ft |
| Dam Length | 410 ft |
| Year Completed | 1860 (166 years old) |
Storage & Hydraulics
| NID Storage | 484 acre-ft |
| Max Storage | 484 acre-ft |
| Normal Storage | 480 acre-ft |
| Surface Area | 33 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 312 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Pacific Gas and Electric Company |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/28/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00365 |
| Federal ID | CA00365S001 |
| More Info | State Dam Safety Program |