16 
G. U. S. Public Health Service Special Study 
Certain water treatment plants on Lake Michigan are of particular 
interest in connection with a special study presently being conducted by 
the U. S. Public Health Service through its Chicago (Region V) offices. 
This study was prompted by the difficulty of many Lake Michigan plants 
to obtain effective water filtration, due primarily to intense seasonal 
plankton blooms. A portion of this study involves the identification of 
water quality conditions which contribute to the difficulty of obtaining 
proper filtration runs. In this connection, efforts are being made to 
standardize observation techniques utilized in the determination of 
chemical, physical, and biological characteristics of the raw water 
taken in by the various plants. 
The study is at present designed to extend through, and possibly 
beyond, 1958. During the period of the study, all participating plants 
will make the following observations, using a standard methodology pre- 
scribed by the U. S. Public Health Service: water temperature, air 
temperature, weather conditions, wind direction, wind speed, lake sur- 
face current direction, turbidity, pH, alkalinity, chlorine demand, and 
chlorine residual. Many of the cooperating plants obtained these obser- 
vations prior to the initiation of the special study; a few expanded 
their operations to include them at least through the present year. 
Water treatment plants are involved at the following locations: 
Green Bay, Wisconsin; Sheboygan, Wisconsin; Milwaukee, Wisconsin; 
Waukegan, Illinois; Evanston, Illinois; Chicago (South District Filtra- 
tion Plant), Illinois; Gary-Hobart, Indiana; Michigan City, Indiana; 
Benton Harbor, Michigan; Holland, Michigan; Grand Rapids, Michigan; and 
Muskegon, Michigan. These plants are identified in Table 1 in the re- 
marks column by the notation USPH cooperator. 
