Fate of Navigation Pool on Mississippi River

Abstract

Humans have altered streams and rivers for economic, commercial, and recreational uses. Low flow depths in navigable rivers have been increased by the construction of locks and dams to facilitate the movement of river traffic such as barge tows. Lock and Dam on Pool 19 on the Mississippi River near Keokuk, Iowa, is the oldest and one of the two highest dams on the Mississippi River. The high storage-capacity-to-inflow ratio causes a high trap efficiency for this pool. The pool is going through a successional change and ultimately will attain a dynamic volumetric equilibrium with an extensive formation of islands, shallow channel border areas, and plant beds. Interactions between the river and its tributaries have also changed, and these confluences are now more like estuaries than river junctions. The deltas, islands, and shallow wetlands near the confluences are the end products of these changing interactions. The dam has changed the Des Moines Rapids into a biologically productive pool with extensive beds of aquatic macrophytes and burrowing macroinvertebrates, which attract migratory waterfowl and fish.