464 



Transactions of the Canadian Institute. 



[Vol. VII. 



During the high water of April, May and June the strength of the 

 solution would be considerably less than .004 per cent., and as chub and 

 brook trout were caught on and off all summer below the mill, this 

 strength of sawdust solution was certainly not strong enough to kill off 

 all the fish, though it is quite conceivable that it might drive fish down 

 the river into tributary streams where there could be no sawdust 

 pollution. 



Comparing this percentage with that in two of the laboratory ex- 

 periments described on pages 450 and 452 we find that in one case two 

 grams of white pine sawdust in 1,700 c.c. of fresh water, i.e.^ .12 percent, 

 strength, soaking for five hours, killed a minnow in twenty-nine minutes ; 

 and in the other case a percentage of .16 killed in ninety minutes. 





Slabs, edgings and sawdust, half-a-mile below the mill. 



Of course, these figures are mere approximations, but they point 

 unmistakably to the conclusion that the sawdust poured into the 

 Bonnechere river is not destroying its fish life. Moreover, in Golden 

 Lake, an expansion of this same river, and ten miles above any saw 

 mill, lake trout used to be very abundant. Every October large num- 

 bers were caught in nets along their spawning beds. Now these spawn- 

 ing grounds are reported to be deserted by the fish, and certainly 

 sawdust cannot be blamed for their disappearance. Higher up the river, 

 in Round Lake, the October fishing is still good, solely because there 

 are fewer settlers and less fishiner. 



