The barrel sat in the same spot for decades and only emerged when the lake receded to the current record-low water level of 1,049 feet, the lowest since the lake started filling in late 1934, amid declining snow melt from the western Rocky Mountains that drains into the Colorado River, and an exceptionally intense 22-year-long drought in the Southwest. Lake Mead’s water supply has dropped 22 feet in the past year, and the U.S. Bureau of Reclamation projects it will drop another 26 feet by fall 2

Dig into the engineering of the Hoover Dam, a massive hydroelectric dam that supplies water to the US southwest: | TED-Ed