LXXVIII. REVIEW OF WATER CONSERVATION IN N.S.W. 
rainfall on the area of the catchment, would as a matter 
of fact, fill twenty such reservoirs. After the dam was 
finished, it took over a year to fill up to top-water-level, 
and during this period careful observations were made of. 
the rainfall, and the corresponding height of water in the 
reservoir. An analysis of these returns has been made, 
and it discloses some remarkable facts. During 7 months 
from August to April, the rainfall amounted to 17 inches, 
yet the reservoir gained nothing, but on the contrary, lost 
4 million gallons. In the month of January alone, nearly 
5 inches of rain fell, yet the amount which ran into the 
reservoir was less than one million gallons. The explana- 
tion of course, is that the rain was absorbed by the heated 
ground. In the following May when the weather was 
cooler, the rainfall was nearly 4 inches, and 7 million gallons 
of water were impounded, although this is a more satis- 
factory result, the quantity impounded is only 5% of the fall. 
In the next month, June, another 4 inches of rain fell, and 
no less than 23 million gallons were impounded, this amounts 
to 17% of the fall. In the next month, July, an inch of rain 
sufficed to fill the reservoir to overflowing, so that the 
observations were abruptly ended, but on this occasion it 
is certain that over 25% of the fall must have run off the 
catchment. The conclusions to be drawn from this seems 
to be that summer rains will not flow off this catchment, 
so that half the annual rainfall may at once be put aside as 
entirely lost. Of the winter rains, it may at once be said 
that from 5% to 25% is available if they fall at the right 
time. Taking the whole year round, it appears that this 
superior catchment delivers less than one-two hundredth 
part of its water into the reservoir, a startling fact which 
may well enjoin caution in any future selections of storage 
sites. 
I will now leave the subject of surface waters and briefly 
touch on the underground supplies which are of almost equal 
