165] FAUNA OF BIG VERMILION RIVER— BAKER 67 



POLLUTION OF SALT FORK BY SEWAGE AND 

 MANUFACTURING WASTES 



GENERAL NATURE OF STREAM POLLUTION 



Stream pollution may be broadly divided into two main divisions: 

 contamination by organic sewage from cities and towns and by chemical 

 wastes from factories and mines. Both are inimical to life but the latter 

 is especially fatal to animal life, causing wide stretches of otherwise 

 fertile streams to become veritable deserts. Organic sewage, in a crude 

 or highly concentrated form, is also very injurious, effectually eliminating 

 most forms of life from the polluted body of water. 



The importance and seriousness of the problem of stream pollution in 

 its effect on the life of the rivers and streams into which the contaminating 

 material is discharged has not until very recently been given the attention 

 the subject demands. The diminishing fish supply, and in many places 

 the very objectionable physical character of the polluted waters, have 

 caused the authorities of several states to pass laws governing the discharge 

 of these wastes into streams and the establishment of penalties for dis- 

 regarding these laws. New York and Massachusetts have led in the fram- 

 ing of these laws and other states are following the good example set by 

 these two older commonwealths, where the conditions seem to have reached 

 a maximum of harmfulness (see Ward, 1918, 1919). 



During recent years stream pollution has enormously increased and the 

 problems arising from this condition have been investigated by many 

 biologists and sanitary engineers. The former have studied the problem 

 from the viewpoint of its effect on the useful animal life, especially fishes 

 and river mussels, and this phase probably bears as close a relation to 

 human welfare as any other. Of course, from the standpoint of health, the 

 pollution problem is of paramount importance because of its bearing on 

 such diseases as typhoid fever which may be caused by a polluted water 

 supply. 



Perhaps the worst effect of chemical pollution is to be found in the 

 streams of western Pennsylvania, where water heavily loaded with oil or 

 acid water from coal mines is permitted to flow into the rivers and streams 

 of this part of the state. Studies by Ortmann (1909) show that whole 

 stretches of the Allegheny, Ohio, and Monongahela rivers have been made 

 into deserts, as far as the animal life is concerned, by the large amount of 

 poisonous substances discharged into these streams by the mines, oil indus- 



