- 164 -least decrease the value of those efforts. Such problems manifest themselves most drtamatically in the case of contiguous watercourses, and lakes or aquifers that straddle boundaries, as well as in situations fn which the policies and stant¶ards of an upstream State are less stringent than those ol! its downstream neighbour. But they may also arise in other situations. For example, the less stringent standards of a downstream State may result in harm to fish that migrate to a State lying upstream. Harmonisation of the policies of the various watercourse States concerning water pollution will help to mitigate or avoid these problems. The duty to harmonise policies is a specific application of certain of the general obligations contained in articles 6 and 9, mentioned in paragraph (0) of the commentary to this article, particularly the obligation of watercourse States under article 9 to “co-operate . . . in order to attain . . . adequate protection of an international watercource [system]“. In the presortt case, this means that watercourse States are to work tc/gether in good faith to achieve and maintain harmonisation of their policies concerning water pollution. Harmonixatinn of policies is thus a process in two different senses. First, initial achievement of harmonieation will often involve several steps or stagest it is ’ this aspect of the process that is addressed in paragraph 2, as indicated by t.he words “take steps”. Second, even after policies have been successfully harmoniaed, continuing co-operative efforts will ordinarily be required to maintain their harmonisation as conditions change. The entire process will necassarily depend on consensus among watercourse States. In any event, the idea of harmonisation does not imply that policies must be identical, only that conflicts among them should be avoided or removed. (8) n? requires watercourse States to enter into consultations, if
**Analysis**
The text discusses the harmonization of policies among watercourse states to mitigate or avoid problems related to water pollution, particularly in situations where the policies and standards of upstream and downstream states differ. This suggests that the text is focused on the environmental impact of human activities, rather than economic development, industry, or transportation.

**Category**
Natural resources and environment