The diversity of habitat types, plants, and animals in the Upper Mississippi River has declined considerably over the last 50 years. Of particular interest are losses of aquatic vegetation, loss of islands and side channels behind dams, and changes in river sediments.

One potential cause for these changes is the method of managing water levels, which maintains artificially high water levels behind dams during summer low-flow periods.

The Corps of Engineers experimentally modified their management strategy by reducing water levels in Pool 8, La Crosse, Wisconsin, by 1.5 ft at the dam (no more than 0.5 ft at La Crosse) during summers 2000 and 2001.

The goal is to restore some of the natural processes affecting water movement and sediments, to increase aquatic plant growth and habitat diversity, and to maintain the conditions needed for commercial navigation and public recreation.

This research project will evaluate the effects of the Pool 8 drawdown on water chemistry, sediments, plants, animals, navigation, and recreation and determine how long these effects last.

Resource management agencies need to know the positive and negative effects of this action to help determine if temporary reductions in water level can be a useful habitat management tool in the Upper Mississippi River.