501 



and that the amphipod crustacean, Hyalella knickcrhockcri, put in 

 its first appearance below Dresden Heights. 



The Sanitary Canal at Lockport 



Onr data for the sanitary canal were obtained at Lockport, three 

 and a half miles above the lower locks through which the canal emp- 

 ties into the Des Plaines. They were derived from biological col- 

 lections made at this point September 25, 26, and 27 and November 

 I, 191 1, and August 9 and October 7, 1912; and from chemical de- 

 terminations made November i, 191 1, and February 7, March 18, 

 November i, and November 13, 19 12. The biological data thus 

 represent the conditions of late summer and autumn, and the chemi- 

 cal data, those of autumn and winter, but neither apply directly to 

 those of spring or midsummer. 



General and Chemical Conditions. — At the time of the first visit, 

 September 25, 191 1, the water of the canal at Lockport was clear, 

 like that of Lake Michigan, with much less silt and other suspended 

 matter than the Des Plaines at the same point. It had a slight 

 sewage odor, not particularly offensive; and there was no emission 

 of bubbles of gas to indicate rapid fermentation or putrefaction of 

 its contents. Miscellaneous offal and other refuse was floating or 

 stranded aloug the edge of the canal, much of it but little decayed. 

 In it were recognized grains of com and wheat, melon seeds, tallow, 

 pieces of entrails, bits of human excrement, pieces of old newspaper 

 and toilet paper, fragments of finely chopped straw, and street sweep- 

 ings. The grayish sludge at the bottom of the canal had a foul privy 

 odor combined with a tarry smell like that of the sludge from the 

 bottom of the Illinois River at Morris on the same date. 



Under the colder weather conditions of November i, 191 1, with 

 a surface temperature of the water at 50° F., the odor and general 

 appearance were practically the same as in September. There was 

 perhaps even less appearance of decay in the floating debris. Chicken 

 entrails floating in the water of the canal looked, in some cases, al- 

 most fresh. 



August 9 of the following year the color, odor, and general con- 

 dition of the canal water were practically like that of September, 

 191 1. The water temperature was 64 to 65 degrees F. ; and the 

 depth of the water in the canal was three to four feet above that 

 of the fall of the preceding year. 



The dissolving oxygen of the water, as shown by chemical tests, 

 ranged from .4 of one part per million November i, 191 2, to 9.3 



