|What happens when an international watercourse is shared by three riparians but only states A and B become parties to the UN Watercourses Convention and state C does not? The Convention will only apply to contracting parties, that is states A and B, not to all riparians of an international watercourse (state C) because the definition of ‘watercourse state’, which is applied throughout the Convention’s text to establish various rights and duties, includes only those countries that have ratified the Convention (Article 2(c)). In other words, the Convention confirms that reciprocity is a condition for its applicability, and that the rights and duties established by the Convention apply exclusively among parties. This is standard practice in international law.
Yet, established principles of customary international law, many of which are codified by the Convention, still apply to all watercourse states, regardless of whether they ratify the Convention or not, in the absence of watercourse agreements determining otherwise. For further discussion of these customary law principles, see Section 4.1.2 below, the Preamble and Part II of the Online User’s Guide. This is particularly relevant in the context of over 889 out of 1084 watercourse agreements signed between 1945 and 2007. Although they may not include all riparians, the missing riparians will still be subject to the rules of customary international law. Figure 1.7 on the right shows that of the 1,084 watercourse agreements signed among sovereign countries between 1945 and 2007 only 195 are basin-wide accords which include all riparians – the remaining treaties are mostly bilateral.166
166 N Zawahri, A Dinar, and G Nigatu (2010) Governing International Freshwater Resources: An Analysis of Treaty Design. Paper presented at the ISA Congress, New Orleans, February, 2010.
167 Data is from N Zawahri, A Dinar, and G Nigatu (2010) Governing International Freshwater Resources: An Analysis of Treaty Design. Paper presented at the ISA Congress, New Orleans, February 2010.
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