| Begins | Tuolumne River |
|---|---|
| Ends | Crystal Springs Reservoir |
| Maintained by | San Francisco Public Utilities Commission |
| Length | 167 mi (269 km) |
| Capacity | 905,000 m3 (734 acre·ft) per day |
| Construction began | 1914 |
| Opening date | 24 October 1934 |
| References: U.S. Geological Survey Geographic Names Information System: . Note that map above only shows Bay Area portion of aqueduct. | |
The Hetch Hetchy Aqueduct is a conveyance of Tuolumne River water runoff from federal lands in Yosemite National Park to San Francisco and its client municipalities in the greater San Francisco Bay Area. The system, completed in 1934, is a 167 mi (269 km) gravity-driven network of dams, reservoirs, tunnels, aqueducts and pipelines that delivers , from the Hetch Hetchy Reservoir behind O'Shaughnessy Dam.
The aqueduct splits into four separate Bay Division pipelines at the point where it reaches the city of Fremont. These are called Bay Division Pipelines (BDPL) 1, 2, 3, and 4, with nominal pipeline diameters of 60, 66, 78, and 96 inches (2,400 mm), respectively. All four pipelines cross the Hayward fault. Pipelines 1 and 2 cross the San Francisco Bay to the south of the Dumbarton Bridge. Pipelines 3 and 4 run to the south of the bay.