The Magical Funnel

Monticello Dam, which was constructed in 1953 and finished in 1957, was a challenge to build partly due to the Vaca Mountain Valley’s geology and topography. It was constructed in a site that was much narrower that traditional dams and a location of pure bedrock, which made the contractors think of creative workarounds to its challenges.
One of these challenges was the spillway design. Most dams had spillways located on top of their walls but a design like that needed a much wider canyon to be effective and sturdier. The hard rock of the Vaca Mountains also was a challenge cost-wise as drilling the dam foundation needed to support a traditional spillway design would prove very expensive thus, they came up with a funnel shaped design which had been the perfect solution in controlling Lake Berryessa’s levels.

Inverted Bell

The beautiful and mesmerizing way the water falls into the spillway’s enormous mouth can only be achieved by its edge’s sloping design. Much like a bathtub drain works, the spillway’s bell-mouth design creates a vortex as water flows down its edges and into the tunnel below.
The magical sight of water cascading into the hole can only be witnessed when the level of Lake Berryessa’s contents rises over 440 feet above sea level. This prevents too much pressure to build up against Monticello Dam’s walls, keeping it structurally sound.