The one at Berryessa is of the “bellmouth” persuasion, which is also called a morning glory, plug hole or a glory hole, as the locals refer to it. The lake can hold about 521 trillion gallons of water before needing the morning glory to prevent floods. “It’s a lot of water, but not a lot of velocity,” Mr. King said. In the world of spillways, bellmouths like this one are uncommon, Mr. King added. “You can definitely hear it as it’s cascading,” Mr. King said.

Source: New York Times February 22, 2017 19:30 UTC