tributary streams, and that the intensity decreased rapidly with increased 

 distance fmm the source of pollution. The open waters of the lake, far from 

 large sources of donertic and trade wastes, were free from the more obvious 

 evidences of pollution. Here, only bacteriological analyses were adequate to 

 show that the lake was contaminated by sewage. 



It seemed advisable, then, to divide the area into sections, and to 

 make parallel studies in each section. The way in which the lake was divided 

 is shown in Figure 1. Vfestern Lake Erie was defined arbitrarily as that part 

 of the lake west of a line which touches the Canadian shore at 62* 30' west 

 longitude, runs due south to the International Boundary, and then to the west 

 end of Cedar Point. Western Lake Erie was divided into 5 sections as shown 

 on the map. Obviously the limits of the sections are not natural; of neces- 

 sity they were determined arbitrarily. The sections have been designated by 

 names which described their positions in general: Island, Portage River, 

 Maumee Bay, River Raisin, and Detroit River. 



Early in the season of 1929) a small number of stations were established, 

 and with minor exceptions these were maintained in the following year also. 

 They may be designated as "regular stations", as they were visited at fairly 

 regular intervals. In addition to the regular stations, a large number of 

 special stations were established for special purposes. In order to avoid 

 confusion, these special stations are not shown in Figure 1. Their location 

 will be given in the text or in tables at the proper places in the report. 

 Many of them are shown in Figure 23. 



Data on the location, depth, and type of bottom of the regular stations, 

 by sections, follows: 



Island Section 



Station 18. Location, 3/8 mile SE. 1/8 E. of Mill 

 Point, east shore of Pelee Island. 

 Depth, 7.3 meters. Bottom, sand and 

 cobble stones. 



Station 37A. Location, 3-3/J4 miles ESE. l/Ii E. of Northeast 

 Point, Kelleys Island. Latitude Ul' 36.1;' j 

 longitude 82* 36.3'. Depth, 11^.2 meters. 

 Bottom, mud. 



Station 59A. Location II/16 mile E. of Marblehead Light. 

 Depth, 9.3 meters. Bottom sandy mud. 



Station 82. Location, 3 3/8 miles NE I/8 N. of Port 

 Clinton Light. Latitude, Ul" 33.25'; 

 longitude, 82* $3.U'. Depth, 6.9 meters. 

 Botton, mud. (This station was not 

 visited in 1930) . 



17 



