Los Angeles Aqueduct Jawbone Canyon Pipe, California

This is the largest of the pressurized tubes dipping into and out of the canyons along the Los Angeles Aqueduct (8,095 feet, with a 850-foot drop), and is notable also for having burst in freezing weather in 1988. A few of these siphon points are visible along the course of the original Los Angeles aqueduct which, when it was built in 1913, was the largest single water project in the world, and was especially remarkable for being gravity powered for its entire 226-mile length. In order to flow through valleys the aqueduct is contained in steel pipes, using the pressure developed in the down slope to force the water through the up slope. The Los Angeles Aqueduct supplies Los Angeles with around half of its drinking water.