It conveys water from the Sacramento-San Joaquin Delta through over forty miles of pipelines and canals.
It begins in north-eastern Alameda County on the California Aqueduct's Bethany Reservoir serving as the forebay.
Water flow then continues about nine miles to a junction point where a portion is diverted into a 1 1/2-mile branch line and pumped into Lake Del Valle.
Beyond the Del Valle junction, the water flows by pipeline to La Costa Tunnel, proceeds southwest past Sunol, through the Mission Tunnel, then south through the hills overlooking San Francisco Bay.
The South Bay Aqueduct terminates inside a 160-foot diameter steel tank at the Santa Clara Valley Water District’s Penitencia Water Treatment Plant, located approximately five miles east of downtown San Jose.