34 ANNIVERSARY ADDRESS. 



Mining and Irrigation Department, under the name of Water 

 Conservation and Irrigation Branch, the chief officer of which is 

 Mr. H. G. McKinney, m.e.,Eoj. Unir. irei., m.i.c.e. I am indebted 

 to him for the information I am able to give you on this subject 

 in the following, and feel sure that it will be of general interest. 



Until recent years it was assumed, even by advocates of 

 irrigation, that the rainfall in the Coast District was sufficient 

 for the requirements of agriculture and horticulture, or at all 

 events so nearly sufficient that any outlay on work for irrigation 

 would not be warranted. That a remarkable change has taken 

 place in public opinion is evident when we consider that there 

 are now many irrigated orchards in the Coast District, that the 

 Mulgoa Irrigation Act authorising irrigation from the Nepean 

 River has been passed, and that at least one other private Bill 

 dealing with irrigation from the coastal rivers has been announced. 

 If then irrigation is found necessary near the coast, how much 

 more is it necessary in the western plains where the rainfall 

 varies generally from one-half to one-third of that in the coastal 

 district ? The area of that part of the colony west of the summit 

 of the Dividing Range may be taken at 255,000 square miles, 

 and it is this area which has first to be considered in connec- 

 tion with works for water conservation and irrigation. The 

 mountainous and hilly country between the summit of the 

 Dividing Range and the great alluvial plains may be taken at 

 about 76,000 square miles, and the area of the north-western 

 portion of the colony beyond the catchment of the River Darling 

 at 21,000 square miles. The net area of alluvial plains and 

 undulating country within the influence of the western river 

 system thus amounts to about 158,000 square miles. It is 

 scarcely necessary to state that under the most favourable 

 circumstances a very small proportion of this area can be 

 irrigated ; but only those acquainted with the western plains can 

 appreciate the important effect which irrigated areas, amounting 

 in the aggregate to even the five-hundredth part of the irrigable 

 land, would have on the general prosperity of the country. 



