U.S. Water News Online
DAVENPORT, Iowa -- Mississippi River flooding may be a natural disaster for people that populate the river's banks, but naturalists say the river is simply doing what it has done for thousands of years -- cleansing and rejuvenating itself and its environment.
``When the floodwaters spread out over an area, it provides spawning areas for fish, it helps filter water, it improves water quality,'' said Bob Clevenstine, a river biologist with the U.S. Fish and Wildlife Service, based in Rock Island. ``It tends to tie up pollutants in soil and plant material, breaking them down before they are pulled into the food chain.''
That ecological perspective might meet with skepticism, given the flooded river's muddy, stinky appearance and the fat, dead carp and birds it is expelling as it retreats from Quad-City region streets and parking lots.
Flooding happens more frequently because wetlands that once helped absorb, retain and filter excess water have been replaced by buildings, roads, parking lots and drainage systems that move water much more quickly out of the way and into the river.
``Man has so altered the natural pulse of the Mississippi through agriculture, levees, the lock and dam system,'' said Norm Emerick, a wildlife biologist with the Illinois Natural Resources in Galesburg, Ill.
Manmade alterations to the flood plain, however, can't stop the rivers essential rhythms.
``The river reclaims its flood plain where it's able to, and that includes what's behind the levees,'' said Mike Griffin, a Mississippi River wildlife biologist with the Iowa Department of Natural Resources.
``As the flood plain enlarges ... the native fish and wildlife are adapted to expand into that new habitat. This may be a disaster for us, but it is not at all a disaster for the critters,'' said Dan Sallee, a Mississippi River biologist with the Illinois Department of Natural Resources in Aledo, Ill.
``Actually, you may see fewer animals because the habitat has expanded so much that they aren't as concentrated as they would be in low water conditions. The herons need water less than thigh deep that they can stand in and fish. If you provide that on River Drive, they'll use it,'' he said.
``In nature, the river connects with its flood plain during periods of high flow and rejuvenates those area, restocks those areas with fish, wildlife, and re-colonizes those areas and makes them more productive as far as ecosystems go,'' Griffin said. It's less productive for farmland, and yet the silt it deposits in its wake provides fertile material for growing, he said.
``We try to control the river from getting into the flood plain. It wouldn't get to the magnitude it has gotten in recent years if the river could spread without the constraint of levees,'' Griffin said.
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