The general character of the watershed from which the 
water would be collected is similar to that of the Enoggera 
Y alley, and the quality would no doubt be identical. 
In addition to this reservoir on the north branch of Moggill 
Greet, there is a site suitable for a second reservoir on the main 
branch of Moggill Creek ; but the waters would have to be con- 
veyed by pipes a distance of four miles to the head of the open 
conduit. 
The supply from each of these reservoirs may be fairly 
estimated at 500,000 gallons per diem in seasons similar to the 
past two years, when the Enoggera Reservoir has had a capa- 
bility of 700,000 gallons per diem. 
As regards the relative cost of obtaining one million gallons 
of water per diem from the Moggill Valley and the Brisbane 
River, it may be estimated that each of the Moggill Reservoirs 
and its accompanying works could be constructed for £50,000, 
while the first cost of the works for bringing the water of the 
Upper Brisbane to the city would be more than £100,000. In 
the former case the water would be delivered by gravitation at 
the highest level in the city, and in the latter it would have to 
be pumped 280 feet by steam power. 
In seeking for sources of water supply, the possibility of its 
being obtainable from wells of the ordinary artesian class should 
always be considered ; for, though well water is usually deficient 
in “ softness,” this defect is generally more than compensated by 
the greater freedom from organic impurity. Ordinary wells are, 
however, only available for large supply where there are exten- 
sive beds of gravel or sand belonging to tertiary or recent 
alluvial drifts. Artesian wells can only be formed where there 
are inclined beds of porous material interspersed between per- 
meable strata of clay and rock, conditions confined to formations 
above the carboniferous series of rocks. 
The older Devonian slates and carboniferous shales of the 
district ar ound Brisbane are so impervious that nearly the whole 
of the rainfall flows oft by surface channels, there being no beds 
of sand or gravel to form subterranean reservoirs, while the 
rocks are so impregnated with iron pyrites that the small quantity 
of water retained in the small fissure is unfit for domestic use. 
As wells are impracticable, and there are no copious springs, 
it is necessary to resort to storage of the surface drainage of the 
country either in natural or artificial reservoirs. 
The Brisbane River is a natural reservoir of this character, 
not being supplied from springs, but consisting, in the dry 
season, of long reaches of nearly stagnant water, with a small 
flow over the intervening banks of sand and gravel resulting 
from the gradual drainage of the upper part of the channel. 
"Whether the storage be in these reaches of water, or in 
artificial reservoirs in the upper parts of tributary valleys, the 
