Drum Afterbay
Drum Afterbay is a concrete dam located in Placer County, California, built in 1968. It carries a Low hazard potential classification and has a satisfactory condition assessment.
About Drum Afterbay
The primary purpose of Drum Afterbay 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 Bear River.
The dam stands 102 feet tall and stretches 356 feet across, creates a reservoir covering 10 acres, has a maximum storage capacity of 341 acre-feet, and collects water from a drainage area of 12 square miles. Completed in 1968, the structure is well into its service life at over 50 years old.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. The most recent inspection on record was 09/20/2022.
At 102 feet, this dam is taller than 98% of all dams in the United States.
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Location
| State | California |
| County | Placer |
| Nearest City | None |
| River/Stream | Bear River |
| Coordinates | 39.25440, -120.77500 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 102 ft |
| Dam Height | 102 ft |
| Dam Length | 356 ft |
| Year Completed | 1968 (58 years old) |
Storage & Hydraulics
| NID Storage | 341 acre-ft |
| Max Storage | 341 acre-ft |
| Normal Storage | 181 acre-ft |
| Surface Area | 10 acres |
| Drainage Area | 12 sq mi |
| Max Discharge | 5,300 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Pacific Gas and Electric Company |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/20/2022 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | CA00421 |
| Federal ID | CA00421 |
| More Info | State Dam Safety Program |