The data show that the bottom was polluted at all of the 

 regular stations in the Maumee Bay Section. In order, then, to 

 determine more definitely the extent of the polluted area, samples 

 were taken at numerous special stations along lines radiating from 

 the outermost regular station (2514), and at other points of special 

 interest. Some of these special stations were sampled in 1928 also. 

 The data collected will be discussed in the two following sections. 



Extent of pollution out from the 

 mouth of Maumee River 



Table 88 shows the abundance of Tubificidae and Hexagenia at 

 12 stations located on a straight line between Station 2$0, at the 

 mouth of the river, and Station 13U, approximately twenty miles out in 

 the lake. In addition to the three regular stations of the Maumee 

 Bay Section, and Station 13U, eight special stations are shown. The 

 locations of these special stations with reference to Station 250 are 

 given in the table, and in Figure 22 and Figure 23. All of the 

 stations in this series had predominatly mud bottom. 



Station 25l, situated about equidistant from Stations 250 

 and 252, had almost as many Tubificidae as Station 250, but about 

 11 times as many as Station 252. It will be remembered that dredging 

 operations were carried out at Station 250 before these samples were 

 taken, and as a result the number of Tubificidae in 1930 was much less 

 than in 1929. Had it not been for this dredging, the data of 1930 

 undoubtedly would have shown a greater dropping off of Tubificidae 

 between Stations 250 and 251 than between Stations 25l and 252. 

 Regardless of this point, it is obvious that the dividing line between 

 the zones of heavy and moderate pollution should be placed between 

 Stations 25l and 252, Between Stations 252 and 253 there was a decrease 

 of several hundred worms per square meter, and a change from moderate 

 to light pollution. In passing from Station 253 to Station 25U we note 

 an increase in the Tubificidae, probably as a result of the "syotty" 

 distribution of the organisms. Both stations belong in the zone of 

 light pollution. 



At Station 255, only one mile out from Station 25U, the single 

 sample showed a total absence of Tubificidae, and the presence of 

 more than 100 Hexagenia per square meter. There may be some hesitation 

 in relying on the results of a single sample, but certainly the results 

 at Station 256, one mile farther out, indicate conditions typical of 

 unpolluted bottom such as was found in the Island Section. It is 

 obvious that the line dividing the zone of light pollution from the zone 



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