Lake Berryessa - Morning Glory Spillway

Lake Berryessa was formed when the Bureau of Reclamation built Monticello Dam on Putah Creek in 1957.  Project purposes included flood control, municipal and industrial water supply, and irrigation water supply. Lake Berryessa is located in northern California; the Monticello Dam's is the largest Hydroelectric Power Plant is owned and operated by the Solano Irrigation District.

The Morning Glory Spillway (Glory Hole) is the funnel-shaped outlet that allows water to bypass the dam. This funnel-shaped outlet lets water to bypass the dam when it reaches to its maximum capacity (1,602,000 acre-feet), as it swallows a rate of 48,400 cubic feet per second (1370 m³/s). The distance from the funnel to the exit point is situated in the south side of the canyon approximately 700 feet.  This kind of spillway is mainly a massive cement funnel.

The Hole’s narrows diameter is 28 feet and largest diameter is 72 feet. For some clear reasons, swimming near the glory hole is prohibited. There’re buoys strung across the lake to stop boaters and swimmers from approaching the glory hole and the dam. Moreover, the glory hole is well fenced off from the land.  The Lake Berryessa Recreation area is Federally-owned, public land administered by Reclamation. The name of Berryessa is from two brothers with the last name of Berryessa.  The brothers, Jose Jesus and Sisto Berryessa, owned a considerable portion of the land in and around the town of Monticello, now covered by the waters of Lake Berryessa.

A spillway is a structure used to provide for the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. Spillways release flood water due to security reasons not overtop, damage & destroy the dam. It is normally used in rain seasons or flood periods when water doesn’t flower over a spillway. Moreover; to release water on a regular basis for water supply, hydroelectricity generation, etc. Floodgates and fuse plugs may be designed into spillways to regulate water flow and dam height.  The other uses of “spillway” include bypasses of dams or outlets of a channels used during highwater, and outlet channels carved through natural dams such as moraines.