March, 1963 



Larimore & Smith: Fishes of Champaign County 



311 



to only 8 per cent of the area of the 

 county. 



When Thompson & Hunt made their 

 collections in 1928, 74 per cent of the 

 county was in drainage districts. By 1959, 

 82 per cent of the county (520,100 acres) 

 had received drainage improvements. Of 

 the 18 per cent of the county remaining, 

 probably a considerable proportion has 

 adequate natural drainage or is in non- 

 agricultural use. Future drainage probably 

 will consist mostlj'^ of maintenance and 

 improvement of existing systems. 



Dredging to increase the water-carrying 

 capacity of existing streams, or to create 

 ditches in the undrained marshy areas 

 where none existed, eliminated areas of 

 standing water and created new channels. 

 Recanalization of natural streams re- 

 sulted in much straightening, in the erec- 

 tion of high earthen banks along the sides, 

 in producing greater uniformity of the 

 stream environments, and in drastically 

 altering local habitats, fig. 11. 



Subsurface drain tiles reduced areas of 

 standing water and in some places resulted 

 in burying what had been surface drain- 

 age courses. As a result, many small, in- 

 termittent streams have been replaced by 

 field tiles or by wide, carefully graded 

 grass waterway's. 



Draining and dredging, which have re- 

 duced the water storage capacity of the 

 watershed, have contributed to higher 

 flood levels and lower drought levels in 

 the streams. These practices have lowered 

 the water table and affected the perma- 

 nency of many small streams. Since the 

 early 1870's, work has been directed to- 

 ward improving the drainage in Cham- 

 paign County; in the future this objective 

 may need considerable modification as de- 

 mands for water supplies increase and ef- 

 forts are made to hold water to meet 

 these demands. 



Some stream courses have been altered. 

 Slight changes in drainage boundaries can 

 be seen on the upper reaches of Hayes 

 Creek, Copper Slough, Camp Creek, the 

 Salt Fork above Rantoul, and the head- 

 waters of the Little Vermilion system. 



Two stations where Thompson & Hunt 

 seined, one in a small tributary of the 

 East Branch of the Salt Fork about 3 

 miles southeast of Rantoul, and one in a 

 tributary of Hayes Creek on the Cham- 



paign-Douglas county line, were no longer 

 extant in 1959. They had been replaced 

 by grass waterways. Near St. Joseph, the 

 Salt Fork had been straightened, leaving 

 a large oxbow at the west edge of town. 

 Numerous small streams visited in 1928 

 by Thompson & Hunt were completely 

 drj' in the summer of 1959, due probably 

 to the dry summer rather than to modi- 

 fications by man or to long-term natural 

 changes. 



Some stream changes, including new 

 channels and new meanders, were nat- 

 ural. Such changes as occurred in the 

 county between the mid-1870's (shown 

 in red) and the mid-1950's (shown in 

 black) can be detected in fig 6. 



STREAM HABITATS 



Most Champaign County streams origi- 

 nate at drain tiles, fig. 7, on the slopes of 

 moraines, or in flat, marshy areas. They 

 flow through straight, usually man-made 

 ditches in rich farmland and move on 

 into less disturbed channels as they be- 

 come larger and their valleys widen. Cer- 

 tain general ecological characteristics are 

 common to these streams and can be used 

 to distinguish and describe several stream 

 habitats. 



General Ecological Characteristics 



In Champaign County, the relatively 

 flat topography, the lack of rock outcrops, 

 the similarity of soil materials, and the 

 intensive land-use practices produce an 

 unusual amount of uniformity in the 

 stream environment. 



The stream gradient is generally low, 

 usually between 3 and 4 feet of fall per 

 mile. Only on the slopes of moraines and 

 in a few short stretches does it exceed 6 

 feet per mile. The flow is generally mod- 

 erate to sluggish during normal water 

 stages. Riffles are gentle and pools are 

 rather shallow. There are long stretches 

 of very uniform depth and flow. 



Water levels fluctuate rapidly and dras- 

 tically. Flooding occurs with some reg- 

 ularity, particularly during the spring and 

 early summer. At normal water stages, 

 streams have levels well within their 

 steep-sided banks. During flood stages, the 

 water levels may rise 10 to 15 feet and 

 temporarily become torrents that erode 

 away stream banks. Within the county, 



