including the provision of technical assistance, joint financing, the exchange of specific data and information ,and similar forms of joint participation and co-operation. To the same effect, see comment (b) to article X of the Helsinki Rules, Helsinki Rules, fbta., p. 499, m/The Conunissio*. recoqniaes that it may be regarded as somewhat awkward to speak of “harm . . . to the use of waters . . .‘I, but preferred not to use another expression (such asr for example, “interference with the use of the waters” ) , at least at the present stage of its work, since other expressions could raise doubts as to whether a uniPurm standard was being applied in the case of each illustration. The present wording leaves no doubt that the same standard -that of appreciable harm - is utilised in all illustrations. lLiu/ Such amenities may include, e.g. the use of a watercourse for recreational purposes or for tourism, - 163 -State6 is intended to encompass, in particular, matters of the latter kind. m/ It is thus broader than the concept of the “ecotiystem” of an international watercourse [system], which is the subject of article 22. (7) The final sentence of paragraph 2 requires watercourse States to “take steps to harmonise their policies@@ concerning the prevention, reduction and control of water pollution. This obligation, which is grounded in treaty practice J.$).g/ and which has a counterpart in the 1982 United Nations Convention on the Law of the Sea, 2441 addresses the problems that o%ten arise when States adopt divergent policies, or apply different standarda, concerning the pollution of international watercourse[s] [systems]. For example, if the standerds applied by watercourse State A are quite stringent, while those of watercourse State B are lees so, the less stringent standards of State R, if