PROBLEMS OF THE ARTESIAN WATER SUPPLY OF AUSTRALIA. 137 



the water ceased to rise above the surface. A notable 

 instance is that of the basin from which the city of Denver 

 draws its water supply. It was discovered in 1884 and 

 within a few years about 400 wells had been drilled, 

 principally within the city; by the end of 1890 all but six 

 of the city wells had to be pumped. 



Professor Slichter, in commenting upon the fact, states 

 that it is probably due to the low porosity and transmission 

 power of the water bearing strata, rather than to the lack 

 of rainfall upon the catchment area, and that the water 

 withdrawn represents a supply stored in the rocks but not 

 readily transported by the strata to meet the enormous 

 draft. He adds — 



"It must be kept well in mind, that there is a limit to the 

 amount of water that can be withdrawn from an artesian basin. 

 There is no such thing as an inexhaustible supply in this 

 connection. The amount of water available is limited on the one 

 hand by the amount of rainfall upon the catchment area, and the 

 facility with which the rainfall can obtain entrance to the porous 

 stratum, and on the other hand by the capacity of the water-bearing 

 rock to transmit the water over long distances, and diminution 

 through leakage and seepage. These two limiting conditions are 

 usually of sufficient magnitude to render the overdrawing of the 

 supply a practical and present danger which should be constantly 

 kept in mind." 1 



In Queensland and New South Wales increasing numbers 

 of bores are giving diminished flows, and in some, for 

 instance the shallow bores on Killara Station in the Bourke 

 district, the water has ceased to rise above the surface. 

 In nearly all these cases the bores are situated near the 

 margin of the basin, where one would expect the first sign 

 of depletion to manifest itself. It is unfortunate that 

 accurate records were not kept, from the first, of pressure 



1 The Motions of Underground Waters, C. S. Slichter, 1902. Water 

 Supply and Irrigation Papers U,S. Geol., Sur., No. 67, p. 94. 



