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INTRODUCTION 19 



provement in health coincides with the completion of works 

 of sewage and the introduction of a better water-supply. In 

 Sydney, New South Wales (population 427,000), the death- 

 rate, which was 26*8 per 1,000 in 1875, has fallen consistently 

 as the sewered area has increased, and was 13 per 1,000 in 

 igo2. At Melbourne it was 25*8 in 1875 and 14*4 in 1900. In 

 other towns similar reductions have been shown, and in most 

 cases "alterations or improvements in the methods of sewage 

 disposal seem to be the main, if not the only, determining factor. 



Tidal Discharge. 



The Rivers Pollution Prevention Act, 1876, provides that 

 before discharging domestic sewage or trade refuse water into 

 any " stream " the public or private persons responsible shall 

 duly see that '' the means used for rendering harmless any 

 sewage matter or poisonous, noxious, or polluting solid or 

 liquid matter falling or flowing or carried into any stream are 

 the best or only practicable and available means under the 

 circumstances." The Act defines that "a stream includes the 

 sea to such extent, and tidal waves to such point, as may, after 

 local inquiry and on sanitary grounds, be determined by the 

 Local Government Board . . . save as aforesaid, it includes 

 rivers, streams, canals, lakes, and watercourses ; " virtually, the 

 Act permits the discharge of crude sewage into the sea at 

 extreme low-water mark, and into a tidal river with sufficient 

 volume of dry-weather flow and tidal rise. The Local Govern- 

 ment Board's report on sewage disposal of 1876 provided that 

 " towns situate on the sea-coast or on tidal estuaries may be 

 allowed to turn sewage into the sea or estuaries below the line 

 of low water, provided that no nuisance is caused, and that 

 such mode of getting rid of sewage may be allowed and justified 

 on the score of economy." 



Many seaside towns discharge their sewage on the foreshore 

 near low-water mark, but a great portion is returned by the 

 tides, and the serious nuisance often occasioned has led to a 

 widespread agitation against the practice. Sea water is not a 

 satisfactory medium for the purification of crude sewage, partly 

 because it contains a comparatively small number of water 

 bacteria, but mainly because the tidal disturbances prevent the 

 suspended organic matter from undergoing the sedimentation 

 which allows organisms growing in the absence of air and light 

 to do their necessary resolving work. 



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