WATER CONSERVATION SURVEYS OF N.S.W. LXXV, 
of the heights of several of our rivers had been maintained by the 
Government Astronomer, and some had also been kept by the 
Department of Harbours and Rivers ; but the information thus 
recorded was intended chiefly for use in connection with naviga- 
tion. In many cases no records were entered when the rivers 
were low, and in some cases the gauges were so fixed that their 
zero was above the water level when there was a discharge of 
many hundreds of cubic feet per second. While the records kept 
under such circumstances were undoubtedly of great value for 
purposes of navigation, the fact that they took little or no account 
of low discharges, rendered them of comparatively little use so far 
as questions relating to water conservation were concerned. There 
were thus two great questions to be taken up and dealt with— 
the first, to ascertain what quantity of water was available for 
distribution and utilization, and the second, to determine the 
directions and extent to which this water could be distributed. 
While it is the main object of this paper to deal with the latter 
question, it may be stated in regard to the former, that gauges 
have been established at all the important points on the western 
rivers, that these gauges have in nearly all cases been connected 
with the general levels of the Colony, and that an extensive series 
of discharge observations has been taken. 
It required little investigation to show that the Central and 
Western Divisions of the Colony are the great field for water 
Conservation and irrigation, and that the great alluvial plains west 
_ of the Dividing Range present both the greatest requirements for 
water and the greatest facilities for its distribution. The natural 
and systematic course of action was, therefore, to determine by 
levels and surveys the rates of fall in the land extending from 
the places where the plains commence, to ascertain the conditions 
of the rivers and creeks under their varying circumstances, and 
to examine the lakes and other natural depressions of importance 
which serve, or could be made to serve, as storage reservoirs. 
“Tn designing the system on which this work was to be conducted, 
the great principle aimed at was to obtain the maximum amount 
