10 ILLINOIS AUDUBON BULLETIN 
and other plant life may also be destroyed by the smothering and/or grinding 
action of heavy sediment loads. The food production capability of the 
stream dwindles proportionately because aquatic plants are the basic life 
support of the stream biota. 
Murky waters are never conducive to strong game fish populations. The 
non-game species, particularly carp and carpsuckers, quickly obtain domi- 
nance in highly turbid waters. Siltation covers or destroys spawning areas, 
and the suspended silt particles may clog gills and respiratory passages of 
many aquatic animals. Siltation and turbidity problems are not limited to the 
immediate channelization work area, but can adversely affect fish and fish 
habitat for many miles downstream. 
Dredging, widening and straightening of streams is accompanied by 
removal of pools, riffles, gravel, and natural stream obstructions, all of which 
interplay to provide food, resting cover and spawning sites. The natural 
stream bottom upon which plants and fish food organisms develop and 
flourish is obliterated. 
Channelization and resulting accelerated water velocities are detri- 
mental to specific life stages of many members of the aquatic community; 
lower organisms often show lethal sensitivity to fluctuations in current 
velocity. The stream may be altered to the extent that some sections may be 
so shallow in dry periods as to be uninhabitable. Shallow water is of course 
more susceptible to increased solar heating. 
Groundwater levels are sometimes lowered, resulting in desiccation of 
backwater lakes, marshes and sloughs. These habitat types, long known for 
their biotic productivity, serve in their unaltered state to store floodwaters, 
nutrients, and sediment. 
Channelization also means the outright loss of aquatic habitat, a loss 
frequently measured in stream miles. The straightened river deprived of its 
so-called unruly curves and bends is considerably shorter. 
Channelization is a violent disturbance of fish and wildlife habitat. 
Damage to the fishery resource is particularly severe and almost always 
irrevocable. In Illinois, over 3,124 miles of natural streams have been 
channelized. After in-depth research, one authority concluded that chan- 
nelization was responsible for destruction of fish habitat over extensive 
stretches of Illinois streams. 
Numerous studies in other states have demonstrated that the numbers, 
