Electra Afterbay

Electra Afterbay is a concrete dam located in Calaveras County, California, built in 1948. It carries a Low hazard potential classification and has a satisfactory condition assessment.

About Electra Afterbay

The primary purpose of Electra 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 North Fork Mokelumne River near Jackson.

The dam stands 30 feet tall and stretches 319 feet across, creates a reservoir covering 1 acres, and has a maximum storage capacity of 50 acre-feet. Completed in 1948, the structure is well-established, with more than 75 years of service.

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 06/14/2017.

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Low HazardSatisfactory ConditionEmergency Action Plan: Not Required

Location

StateCalifornia
CountyCalaveras
Nearest CityJackson
River/StreamNorth Fork Mokelumne River
Coordinates38.33045, -120.67521

Physical Characteristics

Dam TypeConcrete
NID Height30 ft
Dam Height30 ft
Dam Length319 ft
Year Completed1948 (78 years old)

Storage & Hydraulics

NID Storage50 acre-ft
Max Storage50 acre-ft
Normal Storage1 acre-ft
Surface Area1 acres
Spillway TypeUncontrolled

Ownership & Safety

PurposeHydroelectric
OwnerPacific Gas and Electric Company
Owner TypePrivate
Hazard ClassificationLow
Condition AssessmentSatisfactory
Last Inspection06/14/2017
Emergency Action PlanNot Required

Identifiers

NID IDCA10426
Federal IDCA10426
More InfoState Dam Safety Program

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