Habitat changes in the Upper Mississippi River floodplain

The floodplain of the Upper Mississippi River has been significantly modified by man
since 1824.  Changes include the  removal snags and sandbars, elimination of rapids,
closing of side channels, construction of wing dams, 29 navigation locks and dams, and
hundreds of miles of levees.  Watershed changes have transformed much of the landscape
from forest/grassland habitats to agriculture.  We studied floodplain changes by analyzing 
historical water elevation and discharge data  collected since 1861 and spatial data since
1891.  Open water and marsh habitats have generally increased in the dammed portion of
the river.  A 28% reduction in open water and a 38% reduction in woody and terrestrial
habitats have occurred In areas unaffected by dams.  Water levels as a function of
discharge have changed significantly at both low at high flow levels.