Section IV., 1911 [25] Trans. R.S. C. 
Three Years’ Analyses of Ottawa River Water. 
By F. C. Harrison, DSc., Macdonald College, P.Q. 
(Read May 17, 1911.) 
In a former publication’ read before this Society, the writer gave 
an account of the results of a number of analyses of Ottawa river water, 
the samples being taken from the river opposite Ste. Anne de Bellevue, 
reported experiments on the duration of life of B. coli in this water, and 
made some remarks on the water supply of Montreal. The methods of 
analysis since followed were similar to those mentioned in the former 
paper, and as the present account deals largely with B. coli, I cite what 
was previously stated under “ Excretal B. coli.””— 
“ÆExcretal B. coli,’ which we isolated continually from Ottawa 
“river water at Ste. Anne’s can only to a certain extent originate from 
“the washings of land in cultivation, or from accidental infection. In 
“winter time, the river between Ottawa and Ste. Anne’s is covered with 
“ice from 1 to 2 feet thick, for more than three months, and the only 
“possible source of infection is the sewage of those towns on its banks 
“which have a sewerage system, namely, Ottawa (80,000), Hull (15,000), 
“and Hawkesbury (5,000), with a total population of 100,000. As 
“already mentioned the river above Ottawa is nearly free from B. coli, 
“but the three towns mentioned discharge daily into the river 100 
“gallons of sewage per capita, which amounts to ten millions gallons 
daily 
This large quantity of sewage is diluted according to the amount 
of water in the river at different times of the year, and in order to dif- 
ferentiate this sewage infection from contamination from all sources, 
we must make a comparison of the amount of water discharged during 
the different months of the year. 
In 1908 September and October were the months of very low water, 
and therefore the water discharged during these months is taken as a 
standard of comparison. In April four times as much water is discharged 
as in one of these “standard” months, whilst March has a discharge of 
twice of one of the lowest months. In this way all the months are 
tabulated. 
1 (Harrison and Vanderleck, Bacteriological Analysis of Ottawa River Water, 
Transactions of the Royal Society of Canada, Vol. III, Section 4, pp. 13, 17-18.) 
