12 It is worth noting that at least 83 % of Australia's river networks are characterised by ephemeral systems that experience semi-arid to arid (dryland) climatic regimes (see Thoms and Sheldon, 2000, in Regulated Rivers: Research and Management, 16, 375-383. With respect to NSW, Williams et al. (1998) in Wetlands (Australia), 18(1), 25-48), identified that at least 950 water bodies draining NSW were ephemeral. Nevertheless, scientific definitions do not necessarily prevail in the determination and definition of what constitutes a river in the Australian sense. In Narrambulla Action Group Inc v Mulwaree Council 41068 of 1995 [1996] NSWLEC 199 Bannon J observed:
"Dr O'Loughlin referred to the arid conditions of Australia, and it was plain to me that while his views deserve respect, he thinks of waterbodies in a scientific way, which includes waters such as Coopers Creek, but does not fit the definitions given by the Courts, taken as they are, from European conditions."
13 Correctly or otherwise, the legislative and case-law definitions of what constitutes a river are deeply ingrained with Eurocentric perceptions of what is a river. In Gartner v Kidman [1962] HCA 27; (1962) 108 CLR 12 (30 May 1962) Windeyer J [at para. 13] referred to the often-quoted passage from Angell, J.K. A Treatise on the Common Law, In relation to Watercourses: Intended More particularly as an illustration of the Rights and Duties of the Owners and Occupants of Water Privileges, 5th ed. (1854) p. 3:
"A watercourse consists of bed, banks and water; yet the water need not flow continuously; and there are many watercourses which are sometimes dry. There is, however, a distinction to be taken between a regular flowing stream of water, which, at certain seasons is dried up, and those occasional bursts of water which in times of freshet or melting of ice and snow descend from the hills and inundate the country".
14 This approach was adopted in Knezovic v Shire of Swan-Guildford [1968] HCA 38; (1968) 118 CLR 468 (21 June 1968) by Barwick CJ who said [at para. 18]:
"It seems to me, on an examination of such authorities as exist and of the work of recognized writers on this subject, as well as the decision of the Court, that it is settled that a watercourse consists of a stream with a bed, with banks, and water. That the flow of the water in the stream is intermittent or seasonal will not prevent what would otherwise be a watercourse from being accounted such: but though it is quite true that a watercourse may exist though its bed be dry for some periods, the watercourse, in my opinion, must exhibit features of continuity, permanence and unity, best seen, of course, in the existence of a defined bed and banks with flowing water. It must, in my opinion, essentially be a stream and be sharply distinguished from a mere drain, or a drainage depression in the contours of the land which serves to relieve upper land of excess water in times of major precipitation. It is not enough that the water, when it does flow, does so in what may be seen as a defined course or channel. In the case of a drainage depression, the water being drained off can be expected to flow in the lowest portion of the contours confined by the rising levels of the adjacent land: thus water can be seen when flowing to do so in what could be called a defined channel. If the seasonal rainfall is within an average tolerance in amount and timetable, the flow in the depression may well exhibit some regularity in the depth of water flowing in the contour depression and in the extent to which it spreads as it flows. If there is some such normality in the volume flowing, the impression of a defined channel with limiting margins will be enhanced. If, as I would expect to be the case, there is considerable variation in the rainfall and in the volume and velocity of the water flowing in the depression, the impression of a defined channel may be considerably less. But, in any event, the existence of such a defined channel will not make the drainage depression a watercourse nor the limiting margins of the water's flow in a rainy season or period "banks" of a stream. Thus, though water when it flows in such a period flows in what can be called a defined channel, such a drainage depression will lack banks and a bed in the proper sense of that term, that is to say, identifiable margins of a continuous and permanent stream which contribute to its unity whether or not water is in fact continuously flowing over the bed. The word "occasional" in the quotation from Angell on Watercourses will here, in my opinion, embrace seasonal events, even if they occur with some regularity from season to season. (at p. 476)."