A river expert says the receding Mississippi floodwaters in eastern Iowa are leaving behind a lot of positives. Bob Clevenstine, a biologist with the U-S Fish and Wildlife Service, says the flooding is a natural cleansing process for the river.While it’s no fun to clean up, he says the muddy muck left behind on streets and in flooded basements is silt that’s no longer clogging up the river or important backwater wildlife habitats. He says redistributing the silt is important as the silt dropped in the woodlands and bottomlands provides a fresh layer of earth for new plants. The floodwaters have been around over a month and Clevenstine says that’s also been a positive for aquatic life.The flooded areas give fish more area to spawn, and allows the fish to grow bigger before heading back into the main river. Clevenstine says that means some species of fish will increase in population — something that’s good for the fish — and the people who try to catch them.