Jeffrey Mount and Jay Lund (UC Davis water guys) draw lessons for California from Morganza and the lower Mississippi:
In the Central Valley, those in the floodplain operate under an old adage: You hope that the other guy’s levee fails first. For political, economic and legal reasons, our institutions have been unable to move beyond this ad hoc system toward a new paradigm – designating areas suitable for emergency floodwater storage and bypass, and providing adequate compensation as an incentive.
Further levee lessons are provided courtesy of blues lyrics – if it keeps on raining, the levee’s going to break. when the levee breaks, honey you got to move…..
The Dutch apply cost benefit to this question, which is the right way to go. Apparently the Yolo Bypass (near Sac) has an agreement for flooding, but I am not sure it has automatic triggers (i.e., no advance permission required.)