1909.] FRESH-WATER FAUNA IN PENNSYLVANIA. 97 



nitely. If we further consider the fact that the state is trying to 

 restock our streams artificially, this might entirely counterbalance 

 the losses caused by the fisherman, and thus we may say that fishing 

 alone would never destroy our fish fauna. 



B. Pollution of Streams. 



The worst damage to our fauna is done by the pollution of the 

 streams, that is to say, by the discharge into them of substances 

 which are directly injurious to life. This is connected directly with 

 our commercial and industrial progress, and the damage done by it 

 is irreparable, unless there is some radical change in the way of the 

 disposal of the industrial refuse, which at present is generally 

 allowed to run directly into the nearest stream. 



The most widely distributed pollution of a stream is by sewage 

 from the larger towns and cities. This in itself is rather innocent. 

 I am not discussing the deterioration of the waters from a sanitary 

 standpoint; but with regard to animal life in our rivers, sewage does 

 not seem to be harmful ; on the contrary, certain forms (fishes, craw- 

 fishes, mussels) seem to thrive on it. Only in a few cases I have 

 seen sewage so concentrated (certain small runs in the city of Pitts- 

 burgh), that animal life is killed. 



Much more dangerous sources of pollution are given by our coal 

 mines. Under this head I unite all sources of pollution, which are 

 connected with the mining of coal, with the coking process, and with 

 the steel industry. This kind of pollution is very widely distributed 

 in the western part of the state. It is a process which charges the 

 water of our streams with certain acids, which, when they reach a 

 certain degree of concentration, directly kill the life.^ A stream 

 polluted by "mine water" is easily recognized (when clear) by the 

 peculiar bluish-green color of the water, and by a peculiar rusty-red 

 deposit upon its bottom. 



Another source of pollution is furnished by the oil zvells and the 

 oil industries. The simple working of an oil well already yields 

 injurious matter: during the drilling of the well invariably salt 

 water is pumped up, and the oil itself is capable of destroying life, 

 if present in excess, and forming, at low stages, a deposit upon the 



"See Stabler H., Water Supply and Irrigation Paper no. i86, 1906, p. 5. 



