For various reasons the results were not presented in this report but 

 it seems advisable to state the general conclusions reached. The 

 tributaries studied were heavily polluted by sewage bacteria. In the 

 lake, only those parts near Detroit Raver and Maumee River were heavily 

 polluted and the intensity of pollution decreased rapidly with increased 

 distance from their mouths. Parts of the lake far from known sources of 

 pollution were only intermittently polluted, and on the average were 

 much less heavily polluted than the tributaries or parts of the lake near 

 the large tributaries. 



Those interested in published reports on baceterial pollution 

 in the Great Lakes may refer to the following: Crohurst and Veldee 

 (1927), Detroit Department of Water Supply (1930), Ellms (1922 and 

 1931), Follin (1916), Gottschall (1930), International Joint Commission 

 (I91U, 1918 and 1918a), Jackson (1912), Mohlmann and Ruchhoft (1927), 

 Ohio State Board of Health (I889 and 1902), Osburn (I926 and 1926a), 

 Streeter (1930), Whipple (1902 and 1913), Zillig (1929). 



The United States Tariff Commission (1927, p. 2 ff.) made 

 some broad assumptions with regard to the role played by pollution in 

 depletion of the fisheries. Representatives of 95 per cent of the 

 fishing companies on the south shore of. the lake and 12 per cent on the 

 Canadian shore stated to the commission's experts that pollution 

 affected their supply of fish. It was then concluded that the findings 

 of the International Joint Commission (I9IU), with regard to pollution 

 in 1913, substantiated the testimony of the companies. The conclusion 

 is wholly unjustified. The Tariff Commission obviously misinterpreted 

 the aims of the International Joint Commission as well as the significance 

 of its findings. The bacteriological survey of 1913 was made in the 

 interest of public health, and the data obtained tell us nothing of the 

 effect of pollution on fishes. A body of water may be unsafe as a source 

 of drinking water for human beings and yet be entirely safe for fishes. 

 There are no known bacterial diseases common to fishes and man, according 

 to Plehn (I92I1, page U52) . It is probably true that bacteria which 

 attack fishes are more abundant in water polluted by domestic sewage than 

 in unpolluted water, because of the additional nutritive materials 

 available, but it is unsafe to conclude, without evidence, that such 

 pollution is a factor in the depletion of a fishery. No investigation has 

 been made of bacterial diseases of the fishes of Western Lake Erie, but 

 there is no reason to believe that the fishes are unusually subject to 

 such diseases. 



Pollution of the bottom 



Studies of mud bottom in the Island Section gave no evidence 

 of pollution. The principal organism present was Hexagenia, a burrowing 

 mayfly which is known to be intolerant to bottoms covered by organic 



3C6 



