64 Remarks on the Report of fhe TVater Commission. 



water. But four feet is a great under-estimate of the average 

 depth. The difference between low neap tides and high springs 

 is about six feet, and the weir would have to be kept some distance 

 (say a foot) above the highest tide, to prevent the sea water from 

 coming over. There would, therefore, be a depth of seven feet 

 over the whole of the reservoir, except the margin between low 

 and high watermark, i.e., the foreshore ; and. this quantity would 

 be exclusive of all that the reservoir would hold at the level of 

 low neap tide. We might very safely calculate this at consider- 

 ably over a foot, as, though the river has some shallows, it has 

 also some deep holes. Only three sections were taken across 

 the river at points about a mile apart, and these give a depth, in 

 the channel, of 33 feet, 41 feet, and 51 feet. Instead, therefore, 

 of 3000 acres at four feet, we shall be within the mark if we 

 reckon 400O acres at eight feet, which would give us a storage of 

 8700 millions of gallons. According to the statement of the 

 Commissioners, if only one inch of rain per annum were 

 impounded from the Greorge's Eiver watershed, it would be 

 capable of affording more than 15,000,000 gallons per diem. As 

 far as regards quantity, therefore, the scheme is unexceptionable ; 

 and though the evaporation from a large surface would be greater 

 than that from a small one, this loss is more than made good by 

 the constant and extensive replenishments the reservoir would 

 receive. 



Of course, as the water is collected at the sea level, it will be 

 necessary, as at present, to pump up all that is wanted for the 

 use of the city. Whatever the advantages of gravitation, 

 they have in this scheme to be surrendered, but we have 

 to set the cost of pumping against the cost of a conduit. From 

 Greorge's Eiver to Sydney will be at the very most ten miles — 

 the Commissioners' conduit would be 63 miles. The difference 

 is 53 miles. The cost of the conduit for 53 miles would be about 

 £240,000 ; the cost of pumping would be about £4 per million 

 gallons. The Commissioners' pipes will only deliver 12,000,000 

 gallons per diem — a quantity that can be easily supplied by 

 pumping. The present engines at Botany supply from 3,000,000 

 to 4,000,000 gallons per diem. It would be only necessary, 

 therefore, to duplicate the capacity of these engines, and have a 

 second pipe to duplicate that rate of supply. 



I have now endeavoured to show that by draining Greorge's 

 Eiver, we shall drain a watershed slightly larger, than that which 

 the Commissioners propose to drain — that the reservoir will hold 

 a superabundant supply — that the w'ater will be of excellent 

 quality — that the smallest rainfalls wall be made available pro 

 quantc — hat the largest rainfalls will all pass through the reser- 

 voir and only what is not wanted will go to waste — that nature 

 will bring the whole supply within 10 miles of Sydney and within 



