Bay. It has been found expedient to present the data from two of these sta- 

 tions with data from the same stations in 1930. For the present only the 

 data from Station 25U will be considered. This station is across the channel 

 from Toledo Harbor Light, and 8-1/2 miles from the mouth of Maumee River. The 

 depth is 6.2 meters. The data obtained here are given in Table 27. 



On three of the four dates there were noticeable differences in the chem- 

 ical constituents at the surface and bottom. There was an abundance of oxygen 

 in all the samplesj in four cases the water was supersaturated, and in no case 

 less than 50 per cent saturated. Associated with this abundance of oxygen 

 there was a deficiency of free carbon dioxide, and high pH. It hardly need 

 be stated that the data d'ford no evidence of pollution. On the contrary, the 

 data indicate that, at this point, the agencies responsible for oxygen pro- 

 duction were more active than those responsible for oxygen consumption. This 

 finding is corroborated by the data obtained in 1929 and 1930, which will be 

 presented in the following pages. 



Season of 1929 



In 1929 it was decided that information concerning the chemical condi- 

 tions nearer the source of pollution (Maumee River) should be obtained. 

 Accordingly Stations 250 and 2^2 were established, at the mouth of the river 

 and at the harbor range lights, respectively. The depth at Station 2^0 was 

 3 meters and at Station 2^2, 3.9 meters. Table 28 shows the data from these 

 stations and Station 2$U. The data are arranged by dates so that changes in 

 conditions can be traced from the mouth of the river out to Station 25U. Only 

 surface samples are shown. In no case was there a significant difference in 

 temperature between the surface and bottom. 



The current of Maumee River is subject to periodic reversals and, 

 except at times of high water, is very weak. Since the water of the lower 

 river is polluted, we should expect to find some correlation between the 

 direction of the current and the chemical contents of the water at Station 

 250, That is, we should expect to find less oxygen and more free carbon 

 dioxide at a time of outflow than at a time of inflow. Yet this would not 

 necessarily be true, because if the water had just started to flow out fol- 

 lowing a long period of inflow, the water at Station 2^0 would be less con- 

 taminated than if it had Just started to flow in following a long period of 

 outflow. In all cases our knowledge of the current was restricted to the 

 time that sanples were taken. 



On June 26, when the current was out of the river, there were only l.i^ 

 parts per million of dissolved oxygen present, representing 17 per cent'of 

 saturation. A marked improvement was noted at Station 252 (U.$ miles dis- 

 tant) where the oxygen content had increased to 6.2 parts per million or 72 

 per cent of saturation. At Station 25^4 there was further improvement, but 

 oxygen was low compared to the samples taken here in 1928, possibly as a 



9h 



