The combination of heavy rain, high velocity winds and rising tides overwhelmed at least two levees yesterday and threatened a number of others.
Late in the afternoon about 50 residents of Twitchell Island were evacuated as water from the San Joaquin River flowed over the levee.
Frank Dietrich, a retired harbormaster described the scene at the marina as he prepared to leave the island.
"F-Dock is completely collapsed. Everything is just getting ripped to shreds. It's really bad. Boats, some of them are going to be severely damaged."
The town of Collinsville was also evacuated when water lapped over a nearby levee.
Throughout the Delta, engineers did patchwork on levees to reinforce them. Overnight local crews closely monitored the structures for leaks and erosion.