PROGRESS IN BrOLOGlCAL INQUIRIES, 1932 143 



areas disturbed by the major pollution centerssuch as the Minneapolis- 

 St. Paul, Davenport-Rook Island, and St. Louis districts, since such 

 silt makes it impossible for the streams to rid themselves of the huge 

 volumes of various organic wastes which are now being poured into 

 these waters. Since the actual volume of municipal wastes has in- 

 creased so enormously during the past few years, and as it is now cou- 

 pled with silt the general pollution problem has become so serious in 

 the Mississippi River and tributary streams that the aquatic life has 

 been practically reduced to those few undesirable forms capable of sur- 

 viving in highly polluted water in large stretches of these streams and 

 the combined pollution is spreading with amazing rapidity. 



MINE POLLUTION IN COEUR d'aLENE DISTRICT IN IDAHO 



In cooperation with the Coeur d'AIene River and Lake Commission 

 appointed by the State of Idaho to investigate mine pollution con- 

 ditions in the Coeur d'Alene district, Dr. Ellis and party conducted 

 a field survey in this district during the month of July. Various 

 samples of material were forwarded to the Columbia laboratory 

 where detailed physiological and biochemical studies were made. 

 A report on these investigations has been sent to the State of Idaho, 

 and the findings may be summarized briefly as follows: 



1. The mine wastes collectively have killed out practically aU 

 forms of aquatic life for 50 miles in the Coeur d'Alene River. 



2. The destructive action of these mine wastes is due to the 

 enormous bulk of finely powdered rock which has literally smothered 

 every living thing on the stream bed, and to the production of toxic 

 substances (chiefly lead and zinc compounds) from the mine wastes 

 which are deposited during high water on the flats along the stream 

 and from which toxic products reenter the stream following high 

 water or rain. 



3. The pollution has extended well across Coeur d'Alene Lake out 

 through Spokane River and into the State of Washington, but has 

 not yet become critical beyond Coeur d'Alene Lake. 



4. The polluted waters of Coeur d'Alene River were found to be 

 highly toxic to both native fish and various plankton organisms. 



5. The experimental work with the various mine wastes and 

 chemicals used in the mining processes demonstrated the toxicity of 

 several of these substances to aquatic life, fish developing typical 

 lead-poisoning symptoms when exposed to combinations of these 

 mine wastes. 



6. Studies made in Canada at similar mines and mills operating 

 under similar conditions show that these polluting materials can be 

 handled by the mines and the stream pollution eliminated, as a 

 method of disposal of mine wastes has already been worked out and 

 is now in satisfactory operation in Canada. 



LABORATORY STUDIES OF POLLUTION 



In connection w^ith all of the above investigations over 5,000 

 samples of water carrying erosion silt have been studied during the 

 past year. These samples were collected from important stations in 

 various parts of the Mississippi Valley, and in Idaho, Texas, Wash- 

 ington, and British Columbia. As a result of these studies the ac- 

 tion of silt on the chemical composition of river waters, the effect of 



