328 



the point of practically complete oxygen exhaustion, a foot below the 

 surface, in midsummer, move 83 miles down stream, from Morris, 

 C3.5 miles below Chicago, to Chillicothe, UG.ri miles below ; and saw 

 the surface dissolved oxygen at the same time of year fall from around 

 ■1 p. p. m. to as low as 1 p. p. m. at Havana, 20T miles below Chicago. 

 During the same five or six years, also, the zone of high free ammonia, 

 with the ratio (per cent) on the base of the total nitrogen between 40 

 and 60 per cent, moved down the river more than 50 miles, or from 

 Spring Valley, 108.6 miles below Chicago, to Peoria Narrows, 160.9 

 miles below ; while the upper limits of the zone of well clarified effluent, 

 with free ammonia around or under 10 per cent of the total nitrogen, 

 receded from Beardstown to Kampsville, a distance of about 5? miles, 

 or to within about 30 miles of the mouth of the 327 mile continuous 

 waterway to Grafton. See charts following. 



Between 1914 and 1918 the total weight of animals slaughtered 

 at the Chicago stockyards (Tables, pp. 331 and 332) had increased at 

 a rate more than eight times as fast as the estimated normal rate of 

 increase of human population; and there had been large increase in 

 the rates of operation of the Corn Products Refining plants both at 

 Argo and Pekin ; while the average dilution employed in the Chicago 

 Sanitary Canal was changed in an amount relatively small. 



The years 1911 to 1911 inclusive had been rather quiescent years 

 for the packing industry, the total weight of animals slaughtered drop- 

 ping off gradually during that time from about 3,3S3 million pounds 

 in 1911 to 3,040 million pounds in 1914. From the 1914 low figure 

 the weight of slaughterings climbed rapidly, with only a slight reces- 

 sion during 1917, to a peak of 4,870 million pounds in 1918. represent- 

 ing an increase of fully GO per cent over the 1914 yearly rate (^Tablc. 

 p. 332) ; and about oO per cent over the average rate of 3.258 million 

 pounds for the four years 1911-1914. 



The increase in the Packingtown wastes entering the sanitary 

 canal in the four years 1914 to 1918 amounted in population equivalent 

 on the basis of the Sanitary District's own figures* to more than 

 523,000 persons, or almost treble the estimated actual increase in human 

 population during the period ; or to more than the total 1920 popula- 

 tion of the city of Buffalo, New York. During peak weeks of 19 16, 



• Packingtown Report II. 1921, pp. 8. 14. 231, etc. 



