tions with regard to oxygen, carbon dioxide, and pH at a distance of U.5 

 miles from the river. It seemed desirable to have data from a point nearer 

 the river, hence Station 251 was established mid-way between Stations 250 

 and 252, or 2.25 miles from the river. Samples were taken also at Station 

 2I49, located at the foot of Madison Street in Toledo, u.75 miles up the 

 river from Station 250. The data from all of the stations are given in 

 Table 29. At Station 2h9, samples were taken at h meters, and at Station 

 250 and 251 they were taken at 2 meters. At Stations 252 and 25U samples 

 were sometimes taken at both surface and bottom, but no important differences 

 were found. All data shown for these stations are from bottom samples except 

 those for Station 25i4 on September 20, which are from the surface. 



The data from Station 2U9 give definite evidence of pollution. In none 

 of the samples was the water as much as 50 per cent saturated with oxygen, 

 and in one was as low as 3>h per cent. Accompanying the low oxygen there was 

 a considerable excess of free carbon dioxide, reaching as high as +7.5 parts 

 per million. The pH was low in every sample. Methyl orange alkalinity was 

 consistently high; the values recorded for this station were the highest 

 found during the present investigation. Itie Ohio State Board of Hnalth 

 (1899) made a study of Maumee River in I898. At a point near Station 2ii9 

 the per cent of saturation with oxygen ranged from U6 to 82, with a mean of 

 60 (five samples). At a point two miles from the mouth of the river, the 

 meah percentage was 70. These figures would seem to indicate less intense 

 pollution in I898 than in 1930, which is entirely in keeping with expectation. 



The data on oxygen at Station 250 show that there were no cases of 

 extreme depletion such as were found in 1929. Samples were taken on two occa- 

 sions when the current was flowin^ out of the river (August 28 and September 9 

 but on both dates the oxygen was unexpectedly high. In fact the 90 per cent 

 saturation on August 28 would be considered unusually high, even if the water 

 were flowing into the river. With two minor exceptions, the samples of 1930 

 showed a considerably higher per cent of saturation than those of 1929 at 

 corresponding phases of the current. On September 20 the water was actually 

 supersaturated. 



Three possible explanations for the higher results of 1930 suggest them- 

 selves. First may be mentioned the possible influence of the set of the cur- 

 rent prior to the time of taking samples. For example, the high results of 

 August 28 would be less surprising if it were known that the current had been 

 flowing into the river for some time, and had just started to flow out when 

 the samples were taken. No data are available to test the validity of this 

 explanation. 



At the mouth of Genesee River, Whipple (1913) found that the warm river 

 water floated on top of the cold water of Lake Ontario. It might be thought 

 that the same phenomena occurs at the mouth of Maumee River, and that the 

 higher oxygen f 1930 could be explained by the fact that samples were taken 

 at a depth of 2 meters rather than at the surface, as in 1929- However, it 

 was found that the upper 2 meters of water was essentially uniform in tempera- 



98 



