134 On the Water Supply of Sydney. 



Art. IX. — On the Water Supply of Sydney from George** River 

 and Cook's River, by Charles Mayes, Esq. 



[Read before the Soeietyl7th November, 1870.] 



In answer to the following invitation from the Commissioners 

 of Water Supply, which I have copied from their report, viz., 

 ' We now invite the closest scrutiny of our results, sensible that 

 if our scheme be in the main the best attainable, it will be im- 

 proved by passing through the ordeal of enlightened criticism ; 

 while if any better scheme still lies undiscovered, this same 

 criticism will, we trust, bring it to light. ' I will endeavour to 

 Bhow that Sydney and its suburbs may be supplied equally as 

 well, both as to quantity and quality, at much less cost than the 

 level scheme proposed by the Commissioners, from either the 

 George's Eiver alone, or the George's and Cook's Rivers combined. 

 Cook's River dam, as you are aware, was constructed in 1835, 

 for the purpose of supplying Sydney with water, and failed, 

 because, for want of skill in its construction, it was not made 

 watertight. On the 6th of October, 1868, 1 received instructions 

 to prepare drawings and specification for a watertight dam, pro- 

 posed to be erected near TJnwin's bridge, just above the present 

 dam, which I now submit to you. 



The cost of the Cook's River scheme will be as follows ; — 



Proposed dam as per drawing and specification £1,400 

 Distributing reservoir at Petersham, from 150 



to 164 feet altitude, to contain 8,000,000 gal. 8,000 

 Engines to raise 4 million gallons per day, with 



engine-house complete 65,000 



Filter beds and pipes to reservoir 20,000 



36-inch pipes from reservoir to Sydney 50,000 



Engineering expenses and contingencies 10,600 



£155,000 



The present level of Cook's River is about one foot above 

 low water outside the present dam, and it is proposed to raise 

 this level six inches higher by the proposed dam as shewn on 

 drawing, when the flood waters or freshets will pass over it ; but 

 there is only about one-third the opening required in the present 

 flood-gates or sluices to take away the floods as they rise. This 

 must be rectified in any case, as the owners of ground on the 

 banks of Cook's River are always liable to serious injury from 

 the flood water being retained by the insufficiency of the present 

 flood-gates, aHhough the highest floods only ris e about five feet 

 above the summer and general levels of the river. The advo- 

 cates of this water supply have endeavoured to obtain an Act of 



