4 COMMISSION OF CONSERVATION 



floods ; yet they certainly will not be as frequent nor as severe as if the 

 impediments to rapid surface drainage were absent. The soil, the 

 litter, the moss and small vegetation, all contribute towards the for- 

 mation of a water reservoir from which supplies gradually reach the river. 



Between these assumed extremes of unfavourable and favourable 

 conditions there exist all the intermediate conditions of surface cover, 

 with corresponding efficiencies in changing surface drainage to sub- 

 drainage : the barren soil covering the rocky slope, the bare pasture 

 of grass and weed growi:h, the ploughed field, the farm crop, the shrub 

 growth and slash, the young forest growth, the old stand of timber, 

 virgin or culled, and more or less dense, — these conditions in infinite 

 variation, vary also in effectiveness as to control of run-off in the 

 sequence given above. 



There is one other influence of the forest cover, even of the poor 

 stands, in regulating waterflow, which other vegetable cover or surface 

 conditions only possess in a smaller degree. Water, as it runs over the 

 slope, is apt either to dissolve soil particles or to carry them in sus- 

 pension, thus eroding the soil, filling the river bed with sediment and 

 decreasing the capacity of the channel. Even a grassy slope is not as 

 efficiently protected against this erosion as a tree-clad one. 



Engineers have sometimes thought that dams alone may effect 

 the satisfactory regulation of the waterflow, but the wiser ones have 

 recognized that, for the best service, dams need to be supplemented 

 by a forest cover such as a watershed furnishes. Especially for city water 

 supplies the practice of forestation of the watersheds has now been 

 generally recognised as essential, mainly for the reason that erosion 

 and the filling up of water reservoirs is thereby prevented. These ex- 

 planations of the importance of the forest influence may perhaps serve 

 to show the bearing of this survey on the Trent canal. 



Causes of Deterioration — At the present time, the pine timber, at 

 least, is practically gone from this watershed. A forest cover still 

 exists, but, with the present commercial value almost entirely extracted, 

 interest in its condition is gone ; fires have swept through it repeatedly, 

 each time causing further deterioration of the forest cover, until, finally, 

 the bare rock condition or man-made desert is the result. At present 

 only beginnings of these conditions can be seen here and there, yet 

 in the three townships of Methuen, Anstruther and Burleigh alone, 

 nearly 150,000 acres of such desert exist. And, if the present policy of 

 indifference and neglect continues, what might have been a continuous 

 source of wealth will become not only a useless waste, but, through the 

 changes which the water conditions will undergo, may also prove a 

 menace to industries which have been developed to utilize the water- 

 powers of this watershed. 



