meters, observed at Station 13h (Middle Sister) on June 25, 192?. Only- 

 one other reading exceeded h meters; a reading of h,S meters at Station 8F 

 (North Passage) on August 9, 1929. Transparencies exceeding 3 meters were 

 uncommon in both years, and most of the readings taken during the summer 

 periods were between 1 and 2 meters . 



In general, stations with highest transparency were those far from 

 rivers or other sources of sediment. There was a decided seasonal change in 

 transparency. The lowest observations were made in spring, the highest in 

 summer; in fall transparency "as lower than in summer but higher than in 

 spring. 



The water in the eastern part of the lake has a much higher transparency 

 than in the western part. Parmenter (1929) reported a maximum reading of 10.5 

 meters and a minimiim of 2 meters for 1928. The average was between 5 and 8 

 meters. 



A CHEMICAL STUDY OF IVESTERN LAKE ERIE 



Introduction 

 Previous Investigations in the Great Lakes 



The Great Lakes have served as a source of water supply for many cities 

 over a long period of time. It is only natural, then, that the waters of the 

 lakes have been subjected to detailed chemical analysis at different times 

 and places to determine their suitability for domestic and industrial uses. 

 Many reports of chemical studies have appeared in well-known publications 

 which are readily obtainable; others have appeared in special publications 

 which are less accessible to the general public. The reports which have 

 come to the attention of the writer will be noted briefly here, but in all 

 probability the list is imcomplete. 



Our knowledge of the mineral constituents of the lake waters is based 

 principally on the investigations of Dole (1909) . Dole made eleven analyses 

 of the water of each of the five Great Lakes near their mouths. The work 

 was done over a period of a year in 1906 and 1907. Table 13 presents the 

 data in summairized form. They are given here as a convenience to those who 

 may be interested, and will not be discussed. 



Dole's report contains data on a number of the tributaries of the Great 

 Lakes. Additional analyses of some of the lake waters and tributary streams 

 are given by Bartow and Birdsall (1911), Clarke (192U), Foulk (1925), Detroit 

 Department of Water Supply (1930), and McNamee (1930). 



In addition to these mineral analyses, a number of so-called sanitary 

 analyses have been made. Reports of such investigations in Lake Superior 

 . and Huron, if mads, apparently have not been published, although Mason (1917) 

 gives the results of one set of analyses from the open water of Lake 

 Superior. Van Oosten (1929) discussed the pollution of Saginaw Bay, Lake 



57 



