No. 2.] EDWARDS — MONTREAL WATER SUPPLY. ll^ 



The Lake waters were perfectly colourless, while the River 

 waters were more or less tinged. 



The waters which supply the city of Montreal and the munici- 

 pality of St. Cunegonde are taken from the aqueduct on the 

 north shore of the river, just below Lachine, aod are the mingled 

 waters of the St. Lawrence and of the Ottawa Rivers in varying 

 proportions at different periods of the year. 



During the winter months the waters of the St. Lawrence are 

 hiijher and more uniformly fed than those of the Ottawa : beino- 

 confined under the ice, they therefore displace the Ottawa water, 

 and, pressing over the rapids at Ste. Anne, they drive the northern 

 waters chiefly over the •' Back River" to the north of fhe Island 

 of Montreal. The extent of this diversion depends partly upon 

 the grounding of the ice about the western shore of the Isle. 

 Perrot and the ice block at Lachine rapids, circumstances which 

 differ in extent and duration at every season, and contribute to 

 the frequent variation of the character of the water supply at 

 Montreal. This difference is more apparent in the color, flavor 

 and comparative clearness of the water than in the results which 

 appear by analysis of the salts which they contain, — the chief 

 difference being in the organic constituents and in the aeration 

 by carbonic acid, and in the presence of alkaline silicates or 

 their neutralization bv calcium salts. 



The present system of supply on the rising main exaggerates 

 the evil of a mixture of incompatible waters by carrying into all 

 the houses below the level of St. Catherine street the suspended 

 matter or dirt, with its accompanying disgusting lower organism, 

 which fill the pipes and accumulate in the closet cisterns, especially 

 in the spring, when the ice breaks up and renders the water 

 muddy, and again during the heavy rains of the fall. 



Of this suspended matter, my friend Dr. G. P. Girdwood has 

 published a record in the Canada Medical Journal, Vol. vii, 

 page 102, showing that in three months' ordinary summer supply 

 the average daily deposit of insoluble mud varies from 2 grains 

 to 4.8 grains per gallon, while under the exceptional circumstances 

 of disturbance, the amount rises as high as 14 grains per gallon- 

 As inhabitants of this mud, he enumerates fifteen forms of animal 

 life, which he found in addition to those wiiich I had previously 

 described in the Canadian Illustrated News (Dec. 7, 1870). 



The following table gives the result of analyses of the Montreal 

 water supply in recent years, and during different seasons of the 

 year : 



