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THE ‘SEMI-OFFICIAL’ ILLINOIS POSITION ON 
STREAM MODIFICATION AND CHANNELIZATION 
Presented to the Conservation and Natural Resources Subcommittee 
Of The House Committee on Government Operations 
By the Department of Conservation, State of Illinois 
Henry N. Barkhausen, Director 
Stream channelization, commonly referred to as channel improvements, 
has come to be an important part of flood control reservoirs, and in some 
cases it is the only structural measure used. Channel work may include 
such things as straightening, deepening, widening, clearing, and snagging. 
It may also include removal of streamside brush and trees outside the 
channel proper. In some cases all phases are used, while in others the 
work is restricted to clearing and snagging within the existing channel. 
While this type of work may constitute improvement with respect to 
getting the water off the adjacent lands more quickly and may reduce 
flood damages, it is extremely detrimental to the stream ecology and 
environment. Other values have been attributed to channel modification 
work such as improved navigation, reduction in erosion, increase in water 
supply for nearby communities, increased recreational opportunities, more 
cropland acreage, enhanced aesthetic values, increased income to local 
residents, and improved fish and wildlife habitat. We do not agree that 
all the foregoing benefits result from stream channelization. Most of the 
values listed are degraded by channel modifications. 
In Illinois most stream modification has little or no effect on naviga- 
tion. Only on those streams where it is specifically designed to improve 
or create navigability is this value realized. A high percentage of this 
work done in Illinois is on streams with too little flow to provide 
navigation. 
The only reduction in erosion is through elimination of stream or river 
bends where erosion normally occurs. It has no effect whatsoever on 
reduction of erosion on the important uplands. The application of land and 
water conservation practices on the upland provides the most important 
erosion control or reduction, and at the same time retards the rapid runoff 
which contributes to flood conditions. If stream bank erosion control is 
a prime objective, it can be achieved by installing revetments or riprap 
which at the same time will enhance the environment for both aquatic and 
terrestrial life. 
On the other hand, it is possible that channelization will, in some in- 
stances, increase erosion. The increased velocity within a channelized 
reach of stream may well cause increased bank and flood plain erosion in 
downstream unchannelized reaches. Furthermore, runoff from the watershed 
of the channelized stream may have a greater velocity and hence a greater 
capacity to carry soil, fertilizer, and soil nutrients into the stream. 
We have recently learned from local residents that channelization of 
Upper Shoal Creek has resulted in increased flooding along the lower un- 
