If you're ever in the area check out the US army Corp of Engineer's Bay Area hydraulic model. It was built 70 years ago to simulate the effects of one such proposal.
There is a museum in SF that shows exactly what would happen if that were to happen. It was proposed in the early 20th century. The conclusions from those experiments they did was it does not end well for most of the bay area if that happens.
Well, sea level rise from climate change isn't gonna end well for most of the bay area either.