118 



Failure of the Van Yean Reservoir. 



population to be provided for. Mr. Blackburn declined 

 giving an opinion on this head, and I think the Select Com- 

 mittee were wrong in limiting the number to 100,000 for the 

 modified gravitation scheme that was to cost 162,000/., but 

 they are in no way identified with the more costly scheme of 

 the Commissioners. A gravitation scheme, involving an 

 outlay of 650,000/. of pubhc money should not be limited to 

 any amount of population short of 500,000. In other words, 

 it should not be commenced at all until an ample supply of 

 water for 500,000 be secured. 



The population of Melbourne, with its suburban towns and 

 villages, is httle short of' 100,000 ; and the amount required 

 for this number, at the rate of 40 gallons per head, per day, 

 would be equal to 8,690,476 cubic yards. Now, as the area 

 of the reservoir is 7,000,000 square yards, this amount of 

 water would give a depth of 3 feet 8 inches in the reservoir, 

 and a population of 500,000 would require a depth of 18 feet 

 4 inches. 



Let us now inquire what amount of water can be supplied 

 to the reservoir. 



The main feature of the Yan Yean scheme is the large 

 reservoir, or natural basin, which has an area of about 1450 

 acres, and a surface of about 7,000,000 square yards, and into 

 which it is intended to direct the greater part, if not the 

 whole of the watershed of the Plenty basin. 



For this purpose an aqueduct of about two miles in length 

 is being now formed to lead the river into the reservoir, and 

 a laro-e^embankment is being raised at the lower end to the 

 height of thirty feet; and, as it is expected that the river will 

 more than fill the reservoir, and that it will maintain a current 

 throuo-h it, there is a waste wash at the height of twenty-five 

 feet it lead back the surplus water to the Plenty. A tower 

 well has also been erected within the embankment, anJ is so 

 arrano-ed as to admit the water into the main pipes by two 

 openino-s, at ten and seventeen feet, from the bottom of the 

 reservoir The third opening at the bottom of the tower well, 

 as explained by Mr. Taylor, is only intended to draw off the 

 impurities that will be deposited from the water. 



The Plenty takes its rise in Mount Disappointment by two 

 main branches, the eastern and the western. The latter, 

 according to Mr. Hodgkinson, takes its source from a con- 

 siderable stream which gushes direct from a fissure m the 

 granite. The eastern branch, as we had lately an opportunity 

 of witnessing, takes its rise from the table land at the very 

 top of the mountain, and, from the smallest possible begin- 



