How dose billy describe the river bottoms?

Billy trains his dogs to hunt raccoons. He spends all summer training them, running them throughout the river bottoms of the Ozarks. But when it comes time for them to jump into the water, they won't go; they are frightened of the water. Billy is determined to teach them how to swim and he eventually does. And even though it was tough, he says that his persistence had no bounds. He was willing to do whatever it took to teach Old Dan and Little Ann to swim.