After seeing this photo, I simply had to find out more. Never even heard of this lake before. The hole is actually a spillway which allows the water to fall 200 feet, creating enough momentum to drive electrical generators. I thought how horrible it would be to be drawn into it! After reading the Wiki account, I learned a lady was, in the '90s! Water spills into Lake Berryessa’s iconic Glory Hole "After a drought-ridden 10-year period, Friday water finally spilled (on its own) into Lake Berryessa’s Glory Hole, bringing an end to the longest gap between spills in the lake’s history. “Surprising,” said Solano County Water Agency General Manager Roland Sanford. “Given where we started, nobody initially thought it could spill this year.” " https://www.yahoo.com/news/m/0fe0b472-ef0f-33d9-834a-6dd6dea80172/ss_water-spills-into-lake.html See: https://en.wikipedia.org/wiki/Lake_Berryessa A view of Lake Berryessa Satellite photo. 20,000 acres, 15 miles long, 3 miles wide.