My parents use to own a home in the neighborhood that had homes destroyed in the recent floods in Southern Utah. They sold it a few years ago and moved a few miles away. They still have friends that live near homes that fall into the flooding river. Normally the Santa Clara River is only a few feet wide and 6" deep. You can step across it. This is a photo looking at what was a new million dollar home that fell into the river when the flooding river under cut the bank under the home. This house was about a hundred yards from the original river bed.

Here are more images of the flood damage http://www.pbase.com/slowpokebill/utah_flood_2005