50 



MARINE AND FISHERIES 



6-7 EDWARD VII., A. 1907 



ON THE BONNECHERE RIVER. 



A final judgment cannot at present be pronounced upon the poisonous effects of 

 sawdust. These effects must be studied near the mills and along the sawdust beds of 

 various rivers. A three weeks' study of the Bonnechere river, a tributary of the Ottawa, 

 much polluted with mill rubbish, led me to modify very considerably the conclusions 

 which I had based upon my laboratory experiments. I visited the mill represented in 

 two of the illustrations of this report fully expecting that not one fish could survive 

 in such surroundings. But pike were abundant for miles below the mill, and fish 

 (chub) could be caught any day along the side of the submerged driftwood. Stranger 

 still, the fish so caught lived for three hours in a pailful of sawdust water drawn from 

 the very centre of a sawdust bed. A few brook trout had been caught earlier in thie 

 season just below the mill when it was running. At the date of my visit, August 20, 

 1902, the mill had been closed for seven weeks and no sawdust was then passing into 

 the river. 



The owner of the mill furnished me with' the data necessary to calculate the per- 

 centage of sawdust in the water passing his mill every twenty-four hours. Tho water 

 contained '004 per cent of sawdust by weight. 



Fig, 5. — Sawmill on the Bonnechere River, a branch of the 

 Ottawa. Sawdust and edgings pass into the river from the 

 end of the mill. 



Comparing this percentage with that in two of the laboratory experimients des- 

 cribed on pages 42 and 43, we find that in one case two grams of white pine sawduat 

 in 1,700 c.c. of fresh water, i.e., -12 per cent strength, soaking for five hours, killed a 

 minnow in twienty-nine minutes; and in the other case a percentage of -16 killed in 

 ninety minutes. That is, there was forty times more water in proportion to sawdust 

 in the Bonnechere river than in one of my laboratory experiments in which a minnow 

 lived for ninety minutes. 



The strength of a cup of tea depends upon the proportion of tea leaves to water. 

 And in the same way, the extent to which any stream is polluted with sawdust depends 

 mainly upon two things, viz.,, (1) the quantity of sawdust, and (2) the volume of water 

 into which the sawdust is discharged. No stream, therefone, can be pronounced off- 



