84 METHOD BY WHICH A PURK WATER SUPPLY, ETC. 



I understand that some experiments have been made by the 

 Board of Water-works to filter the Enoggera water, but without 

 satisfactory results, owing to the excessive amount of organic 

 matter quickly choking the filters. 



How does the Enoggera water become contaminated by 

 organic matter ? It is from the decomposition of Water-lilies 

 tXiiiniihdd <ii<iantea, Hook), Pond-weed {I/i/ihilln), microscopic 

 algse, protozoa, excrement of birds, and from leaves washed by 

 rains into the reservoir. The Enoggera water is rich in 

 microscopic life, it is this that gives the water a bad odour on 

 reaching Brisbane ; at the reservior it is free from bad smell ; 

 whilst in the pipes, in darkness and under pressure, the living 

 bodies die, and by the time they reach town are in a state of 

 decomposition. 



Water-plants and fish have unfortunately been introduced 

 into the Enoggera reservoir ; the plants serve as food for various 

 insects *.//., the lavje of dragon -flies, and also for snails, and 

 these again serve as food for ducks and other aquatic birds, also 

 for fish ; the fish entice cormorants and water-rats, so that the 

 reservoir terms with life. Considerable areas are very shallow 

 and in these parts, not only do the water-weeds grow luxuri- 

 antly, but the water being comparatively still, and much warmer 

 than in the deeper portions, microscopic alga? grow to profusion. 



The excrement of birds is not to be ignored as a factor 

 in contamination although, in the case of Enoggera, owing to 

 the great bulk of water, it is a minor one. 



Recently in this district [Deception Bay] after a drought, a 

 fresh-water lagoon of about twenty acres in extent, two-thirds 

 of which is covered with the large Blue Water-lily, became the 

 resort of thousands of water-birds, the excrement of which, 

 together with the decomposition of water-lilies, increased the 

 impurity from Chlorine 6-0 grains per gallon. 



Free Ammonia '00 | _ .,,. 



.„ ••-1 A • of\ i Farts per million. 



Albuminoid Ammonia -30 ) ^ 



to Chlorine 148-0 grains per gallon. 



Free Ammonia "08 i ^ .„. 



.,, • -1 A -I AA r Parts per million. 



Albuminoid Ammonia 1*00 ) '^ 



The water in this lagoon generally is drinkable, although it 



possesses a very distinct w^eedy taste ; recently it has become so 



foul as to be little better than sewage. 



