Twin Lake

Twin Lake is an earth dam located in Alpine County, California, built in 1903. It carries a Low hazard potential classification and has a satisfactory condition assessment.

About Twin Lake

The primary purpose of Twin Lake 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-tr near Kirkwood.

The dam stands 22 feet tall and stretches 1,520 feet across, creates a reservoir covering 600 acres, has a maximum storage capacity of 21,581 acre-feet, and collects water from a drainage area of 13 square miles. Completed in 1903, the structure is over a century 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 09/07/2022.

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Low HazardSatisfactory ConditionEmergency Action Plan: Not Required

Location

StateCalifornia
CountyAlpine
Nearest CityKirkwood
River/StreamNorth Fork Mokelumne River-tr
Coordinates38.60890, -119.94452

Physical Characteristics

Dam TypeEarth
NID Height22 ft
Dam Height22 ft
Dam Length1,520 ft
Year Completed1903 (123 years old)

Storage & Hydraulics

NID Storage21,581 acre-ft
Max Storage21,581 acre-ft
Normal Storage1,210 acre-ft
Surface Area600 acres
Drainage Area13 sq mi
Max Discharge12,400 cfs
Spillway TypeUncontrolled

Ownership & Safety

PurposeHydroelectric
OwnerPacific Gas and Electric Company
Owner TypePrivate
Hazard ClassificationLow
Condition AssessmentSatisfactory
Last Inspection09/07/2022
Emergency Action PlanNot Required

Identifiers

NID IDCA00384
Federal IDCA00384
More InfoState Dam Safety Program

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