158 Failure of the Yan Yean Reservoir. 
have a very considerable elevation above the bed of the 
Goulburn, without mentioning other difficulties, would render 
such an amount of cutting and tunnelling necessary, that I 
fear the idea must be altogether abandoned. 
Similar difficulties would attend the proposal to bring the 
King Parrot Creek, which is a tributary of the Goulburn, 
into the reservoir. The same dividing ranges would have to 
be tunnelled, and much broken country bridged by aqueducts ; 
but a scientific survey by competent engineers could alone 
determine the question of its practicability and cost. And 
after all, would it be worth while to expend a very large sum 
in conveying so small a stream from so great a distance? Such 
a scheme, I apprehend, must be entirely laid aside until it is 
shown that there is no other cheaper plan of supplying the 
City with water. 
The Diamond Creek claims our next consideration. It is 
a tributary of the Yarra, and, in its upper course, isnot more . 
than six miles distant from Yan Yean. It is more easy, 
therefore, to form an estimate of the probable cost of bringing 
this creek into the reservoir. An engineer, of great practical 
knowledge, assured me that he would not undertake the work 
for 50,0002. Besides, unfortunately it is a very diminutive 
stream, even compared with the Plenty; and, according to 
my judgment, is barely sufficient to supply the wants of the 
village of Eltham and the increasing population of this impor- - 
tant district. 
This proposal, therefore, merits no further notice. 
It only remains to consider the Merri Creek as a source of 
supply, It rises in a swamp of 1,280 acres, which is said to 
have 30 square miles of drainage area, but there is not asingle 
creek or watercourse of any description, leading into it, which 
shows the very small proportion of the rain that drains into 
it from an area of surface equal to one-half of the Plenty basin. 
It is proposed to dam up this marsh, and to lead the water by 
an aqueduct into the reservoir. Let us suppose, therefore, 
that this marsh really does receive the watershed of thirty 
square miles, the area of the swamp being two square miles, 
a rainfall of thirty inches would give a depth of thirty-seven 
feet six inches, and one-ninth, or four feet two inches would 
represent the watershed. ‘This, added to the rainfall of the 
swamp, would give altogether six feet eight inches, which is 
not sufficient to cover the evaporation; and it would, therefore, 
be dry for two months in the year. 
It is useless, therefore, to look to this marsh as a source of 
