This is what happens when engineers build stuff to try to prevent dams from flooding. Recently, California’s dams have gotten a lot of attention after 180,000 people were forced to evacuate their homes because of problems with the Oroville Dam’s spillways. So far, there is no worry about flooding at Berryessa.

Spillways come in many shapes and sizes. 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 structure works a lot like the hole in the side of your sink or bathtub, which keeps water from spilling out onto the floor if someone leaves the faucet running. Only with a reservoir, it works when the rain won’t stop, as has been the case in this area, which has seen four wet storms known as atmospheric rivers so far this year.

When water rises more than 440 feet above sea level in Lake Berryessa, it spills over the lip of the morning glory, funnels down the cone and exits into Putah Creek, on the other side of the Monticello Dam. The lake can hold about 521 billion gallons of water before needing the morning glory to prevent floods.

On Tuesday, water was flowing into the hole at around two million gallons a minute, which is just a small fraction of how fast it can get.