XII. H. G. McKINNEY. 
explain the position more fully, it may be stated that 
throughout the central and western districts of this State 
nearly all the rivers and creeks are intermittent in their 
fiow, and that their courses, where the conservation of 
water is of the greatest importance, generally lie through 
deposits of alluvium. Creeks and flood channels having 
depths of from seven or eight feet to twenty feet and widths 
ranging from twenty feet to a hundred feet are very 
numerous, and as their rate of fall is often not more than 
a foot in a mile, the value of these channels for conserving 
water is at once obvious. Flood channels which have been 
formed by overflows from these creeks, and sometimes old 
channels in which the creeks formerly flowed but which 
have in a great measure been silted up, are used as the 
bywashes in connection with earthen dams. But it fre- 
quently happens that the concentration of the flow in these 
secondary channels has the effect of eroding and enlarging 
them till their beds are brought down to the levels of the 
creeks, so that the dams cease to have any useful effect. 
It then becomes necessary to construct a hew dam across 
the bywash, or to extend the old one with the same object. 
Cases of this kind where the original dam has been extended 
time after time till its length exceeded a quarter of a mile 
are not uncommon, and some are to be found where the 
length is much greater than this. The worst feature in 
connection with incidents of this character is that the 
earth eroded from the bywashes is carried into the creeks 
below the dams. The natural process by which the chan- 
nels of the creeks and rivers are being silted up is sufficiently 
serious to merit careful attention; but this process has 
been greatly accelerated by two causes, both of which 
were in a great measure preventible. The first was the 
wholesale destruction of useful shrubs such as the saltbush, 
and of trees such as the boree and the myall, and the con- 
sequent increase in the destructive effects of dustorms. 
