187] FAUNA OF BIG VERMIUON RIVER— BAKER 89 



pollutional, and (3) contaminated or contaminate; and to these we will 

 add 'clean-water' to indicate the conditions and organisms substantially 

 equivalent to those of the natural, uncontaminated stream." 



Judging Salt Fork by these standards of impurity, we would say that 

 from the Urbana sewage outlet to the first bridge below the Champaign 

 sewer outlet, a distance of about two miles, the stream is in a septic condi- 

 tion. From this point to about two miles below St. Joseph it is polluted. 

 From this region to Homer Park, below the dam, it is contaminated. 

 Below the dam there is probably some contamination at times, but the 

 fauna is a clean water one and the stream would be classed as a clean water 

 stream, being unmodified by sewage conditions. The lower part of Salt 

 Fork near Middle Fork, and Middle Fork and the Big Vermilion as far as 

 Danville are clean-water streams with a large and varied fauna of mussels, 

 crayfish, and insect larvae. Below Danville there is sewage pollution, and 

 conditions are again unfavorable. 



