Cooper's body, had he landed in the Columbia, would not have floated downstream very far. I talked to a rescue and body recovery diver who works on the Mississippi River in the Twin Cities of MN, and he looked up the water temperatures on that night. He told me, with water temperatures near 10 degrees Celsius, Cooper's body would have sunk to the bottom. When his crew does body recovery in such conditions, their search area is a product of water depth alone, not current. Cooper's body would have stayed at the bottom, around the point of entry, until water temperature rose in the spring. From there, Cooper's body would "pop" to the surface and start downstream with the river flow.