CANADIAN FORESTRY ASSOCIATION 87 



FRIDAY AFTERNOON. 



At two o'clock the Chairman called the meeting to order and announced that Mr. 

 Campbell would read Mr. J. S. Dennis' paper on ' Forestry in relation to Irrigation.' 



FORESTRY IN RELATION TO IRRIGATION. 



J. S. DENNIS, Iitrigation Commissioner for the Canadian Pacific Railway Company, 



Calgary ', Alberta. 



Forestry in Southern -Alberta and Western Assiniboia has an aspect not met 

 with elsewhere in Canada. The districts referred to contain vast areas of prairie 

 now recognized as being semi-arid in the sense that during recurring long cycles of 

 years the rainfall is insufficient for the successful production of grain or fodder 

 crops, and irrigation has to be adopted to correct nature's shortcomings. During 

 these dry years many of the smaller drainage channels and most of the surface sup- 

 plies of water in swamps and small lakes dry up, and stock-watering on the open 

 range becomes a serious matter. 



The semi-aridity of the districts referred to constitute, however, a strong feature 

 in their value, and combined with the celebrated il chinook " winds, has proved the 

 region the " ranchman's home." These districts produce practically every year a good 

 crop of grass, the melting snows and spring rains being sufficient to advance the 

 growth to a healthy condition before the hot and dry summer months. The aridity 

 of these months cures the grass grown in the earlier part of the year in such a 

 manner that its nutritive qualities are retained, and cattle ranged at large will keep 

 fat and are fit for beef direct from the range even in winter. 



The soil of this vast district is first-class, and where irrigation is introduced 1 

 will produce bountiful crops, but if the total available water supply of the region is 

 utilized for that purpose not more than 15 per cent of the area can be irrigated, and 

 the remainder must for all time be devoted to ranching and pastoral pursuits. 



Water, it will therefore be seen, plays a more than usually important part in the 

 development of this part of the " Great West," and its conservation is a matter of 

 vital interest. In that conservation forestry takes first place. 



The eastern slopes of the Rocky Mountains and the foothills adjoining, which 

 bound on the west the district under discussion, constitute the great watershed of 

 the region, and all the la"rge streams and main drainage channels of the district head 

 in, or obtain their water from this great run-off area. This watershed is useless for 

 agricultural or grazing purposes, and aside from a small amount of second-class 

 merchantable timber, its great value is as a catchment area to furnish water to the 

 thirsty plains lying to the east. It would, therefore, seem unnecessary to have to advance 

 arguments to support the claim that this watershed should be preserved in a condition 

 best calculated to maintain and improve its usefulness as a catchment area. Unfor- 

 tunately, however, both official and public opinion and knowledge on the subject are 

 very much in need of education, and the Forestry Association is certainly the proper 

 medium for instilling this required knowledge. 



The watershed in question was originally well covered with timber, and in spite 

 of devastating fires and lumbering operations, is still fairly well forested. However, 

 each year sees its timber disappearing, and the restraining influence of the reserva- 

 vation of the area as a forest reserve, instituted some years ago, has unfortunately now 

 also been removed. That the removal of the timber means diminished water supply 



