Physiography of Werribee Area, 



191 



(d) Water Storage. — Since the figures in the last section are the 

 '-only data available for the whole area, and since 1911 and 1912 



were respectively very wet (34 in.), and very dry (19 in.), an 

 iipproximation to the normal discharge might be taken from an 

 average of the two, and would give us about 100,000 acre feet per 

 annum. 



As far as can be learnt, the following are the only tributes levied 

 ^on the river at present : — 



Pyke's Creek Reservoir : Capacity, 14,800 acre-feet. 



Exford Reservoir : Capacity, 10,000 acre-feet. 



Bacchus Marsh (Town) : Domestic supply of town. 



Werribee (Town) : Domestic supply of town. 

 It is very evident that much more can be done in the way of 

 water storage in this basin. Ballan, although situated on the 

 Werribee, draws its supplies from a railway department reservoir 

 on the upper Moorabool, a river also largely utilized by the Bal- 

 larat and Geelong Water Commissions. It seems remarkable that 

 such a fine stream as the Lerderderg River — the dominant stream 

 of the whole basin, and fed by excellent permanent springs in its 

 upper branches, should so far not have been used for storage pur- 

 poses. A small reservoir originally existed on the Lerderderg 

 above the town of Blackwood, the water being wholly for mining 

 purposes, but this dam was destroyed by a flood many years ago. 



(e) Sediinent Carried. — A series of tests of the amount of solids 

 in suspension was made during seven representative months of 

 1890. (See River Gaugings, Vict., 1905 and 1912.) The results 

 were : — 



Date 



Werribee 



River 

 Marsh 



at Bacchus 



Lerderderpf River near 

 Bacchus Marsh 



December 8 



.20 grains 



per 



gal. - 



1.18 grains per gal. ' 



January 13 



.63 







- 



1.82 



February 10 



.27 







- 



1.85 



March 10 



.36 







- 



1.07 



April 13 



.46 







- 



.54 



May 12 



l.'^S 







- 



6.10 



June 15 



2.65 







- 



1.97 



These may fairly be taken to be the natural burden of the 

 streams, uninfluenced by any mining operations. From a con- 

 sideration of the figures, the writer has taken 2 grains per gallon 

 as a fair average of the material carried in suspension. No 

 account is taken of the material in solution. Applying this to a 

 jear for which the more complete data are available, the wet year 



