The Monticello Dam & "The Glory Hole"
The construction of the Monticello Dam in California started in 1953, and it was completed in 1957. The height of the dam is 304 feet, and its length at the top is 1,023 feet. It's volume is 326,000 cubic yards. The Dam is used for produce hydroelectricity and as a resevoir for the people of Napa. However, the dam is most noted for its spillway (overflow controller) which is commonly called "The Glory Hole".
The glory hole is located about 200 feet from the dam. Water spills over its lip when the lake reaches 1,602,000 acre-feet. The funnel’s largest diameter is 72 feet and narrows to about 28 feet. It is designed to handle a maximum of 362,000 gallons of water per second, which occurs when the lake level rises to 15.5 feet above the level of the funnel.
For obvious reasons, swimming near the glory hole is both prohibited and stupid. There are buoys strung across the lake to discourage boaters and swimmers from approaching the glory hole and the dam. Furthermore, the glory hole is well fenced off from the land. The eerie appearance of the spillway in operation attracts visitors, and when the spillway is dry the outlet downstream is popular with skateboarders .