There are houses there? I dont see that many on the Google Earth....how far out of the banks will that river flow?
One million acre-feet and change, divided by the area it spreads out over...it'd take a big comp to crunch but I guarantee you the guys that man that dam have already run it.
PS. DeLormedoesn't display houses, but the street layout of subdivisions is very distinctive. It's not wall to wall residential area, but there are more than a handfull.