The Los Angeles Aqueduct conveys water from the Owens River in the Eastern Sierra Nevada mountains to the city of Los Angeles. The system provides 80% of the water to Los Angeles. Part of the aqueduct system travels through the 5.5 mile (9 km) Elizabeth Tunnel. The San Andreas fault cuts across the tunnel and a major earthquake at this location has the potential to cut off this water supply to the city for over a year.