Lake Valley Auxiliary
Lake Valley Auxiliary is an earth dam located in Placer County, California, built in 1889. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
About Lake Valley Auxiliary
The primary purpose of Lake Valley 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 North Fork American River near Washington.
The dam stands 28 feet tall and stretches 525 feet across, creates a reservoir covering 298 acres, has a maximum storage capacity of 7,964 acre-feet, and collects water from a drainage area of 4 square miles. Completed in 1889, the structure is over a century old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. 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 06/06/2022.
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Location
| State | California |
| County | Placer |
| Nearest City | Washington |
| River/Stream | North Fork American River |
| Coordinates | 39.30150, -120.60030 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 28 ft |
| Dam Height | 28 ft |
| Dam Length | 525 ft |
| Year Completed | 1889 (137 years old) |
Storage & Hydraulics
| NID Storage | 7,964 acre-ft |
| Max Storage | 7,964 acre-ft |
| Normal Storage | 7,700 acre-ft |
| Surface Area | 298 acres |
| Drainage Area | 4 sq mi |
| Max Discharge | 5,200 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Pacific Gas and Electric Company |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/06/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00361 |
| Federal ID | CA00361S001 |
| More Info | State Dam Safety Program |