close up of water jets released at o`shaughnessy dam from hetch hetchy reservoir in yosemite national park; one of the main

alpine america bay california close concrete construction copy dam debit detail drinking energy engineering floodgate flow flowing francisco hetch hetchy hydro hydroelectric industry jet jets lake large main management melt mountains national one overflow park popular power powerful release released reservoir river runoff rushing san sierra snow snowmelt sources space states structure supply system technology tuolumne united usa wall water yosemite