RESPONSE OF MICRO-ORGANISMS TO COPPER 

 SULPHATE TREATMENT 



N. L. Huff 



The object of this paper is to set forth the efifect, upon several 

 micro-organisms, of a series of copper sulphate treatments in Vad- 

 nais Lake during the summer of 1915. The lake was given three 

 treatments during the summer : the first, June 14 ; the second, July 

 12 ; and the third, August 27. The study of the organisms was 

 started on June 11, three days before the first treatment, and con- 

 tinued until the lake was frozen over on December 11. three and 

 one-half months after the last treatment. Unless otherwise stated, 

 the samples which furnished the material for the following results 

 were collected just above the weir where the water, leaving Vad- 

 nais Lake, enters the conduit leading to McCarron Pumping Sta- 

 tion. 



Vadnais Lake is located seven miles north of the city of St. 

 Paul, and has for the most part, high, well-drained shores. The 

 lake is about one and three-fourths miles in length and one-third 

 of a mile in width, covering about 358 acres. Its greatest depth 

 is 57 feet, and the average depth for the entire lake is 27 feet. 



The copper sulphate treatments were carried on by the Bureau 

 of Water, Department of Public Utilities, of the City of St. Paul, 

 for the purpose of destroying the micro-organisms which were ob- 

 jectionable in the city water supply. The writer wishes to acknowl- 

 edge his indebtedness to this Bureau, and especially to Mr. G. O. 

 House, General Superintendent, and IMr. R. L. Smith, Engineer, 

 without whose assistance and cooperation the work would not have 

 been possible. 



The use of copper sulphate for eradicating algae and other ob- 

 jectionable organisms from storage reservoirs and city water sup- 



