It's difficult to describe the hydrological situation of Yuba City and Marysville to people who have never been there. The rivers run through the towns way up above the street level, owing to mining debris washed down from the mountains in the Gold Rush era, and later reinforced by Corps of Engineers works. So if the rivers overflow their banks in Yuba City, the city will be ruinously flooded.

It's really freaky to stand in downtown Marysville and look up at the river bank 15 feet above you.