|Article 5 defines the fundamental rights and duties of states regarding their utilisation of international watercourses by laying down the well-established principle of equitable and reasonable utilisation in paragraph 1 and its complementary principle of equitable participation in paragraph 2.
Despite the fact that the prosperity of societies has always been linked with the development of shared freshwater resources, it was not until the 1950s that customary international law governing international watercourses emerged.175 Before then, two conflicting approaches reflected the claims and counterclaims of states over their share of water resources – the theories of ‘absolute territorial sovereignty’ (also referred to as the Harmon Doctrine)176 and ‘absolute territorial integrity.’ While the former favours upstream riparians, allowing the unlimited use of the waters of a transboundary watercourse located within national borders (regardless of any consequences that may occur downstream in other countries), the latter approach favours downstream states wishing to prohibit any development in an upstream state that would interfere with the natural flow of such a watercourse.177
It was the dispute between the USA and Mexico over the Rio Grande in 1895 which gave rise to the theory of ‘absolute territorial sovereignty.’ In this case, Mexico claimed that diversions in the USA (Colorado and New Mexico) significantly reduced the supply of water to Mexican communities. In protest at the diversion, Mexico declared that its legal right to use the water of the Rio Grande is ‘incontestable, being prior to that of the inhabitants of Colorado by hundreds of years.’178 The US Secretary of State requested a legal opinion of the US Attorney General, Judson Harmon, as to whether the United States violated Mexico’s rights under international law. In the section of his opinion Harmon denied that the general rules of international law imposed any obligation on the United States to restrict its own use of the portion of the Rio Grande within its own territory, even if this use might cause adverse effects downstream in Mexico.
‘The fundamental principle of international law is the absolute sovereignty of every nation, as against all others, within its own territory.”All exceptions […] to the full and complete power of a nation within its own territories must be traced up to the consent of the nation itself. They can flow from no other legitimate source.’
‘The immediate as well as the possible consequences of the right asserted by Mexico show that its recognition is entirely inconsistent with the sovereignty of the United States over its national domain.’
‘[T]he rules, principles, and precedents of international law impose no liability or obligation upon the United States.’179
Attorney-General Harmon therefore advised the Department of State that the USA had no responsibility towards Mexico regarding the significant reductions to the Rio Grande. His opinion is commonly referenced by those who claim an upstream state has a right under international law to act unilaterally in complete freedom over an international watercourse within its territory, irrespective of any impact this action might have in downstream countries. Interestingly, the strong position has never been applied by the USA – neither in the resolution of the Rio Grande dispute, which was based on ‘equitable and acceptable’ use, nor in any following controversy.
The same can be said for general state practice. While some states have, at times, argued they possess absolute sovereignty over the parts of international watercourses located within their own territories; in the end these states have usually resolved their disputes by entering into agreements which recognised the rights of the co-basin states.180
The concept of absolute territorial integrity runs contrary to that of absolute territorial sovereignty, since the former is employed to argue that the upstream state has no right to do anything which may affect the natural flow of the water into the territory of the state(s) downstream. Applying such a theory would most likely have a serious impact on upstream states which developed their water resources at a much slower pace compared to their downstream neighbours, as it would ultimately impede any upstream development which may adversely affect the natural (even seasonal) flow of the watercourse.181
Ironically, the country most closely associated with the theory of absolute territorial sovereignty is also linked with absolute territorial integrity. During the Trail Smelter arbitration, a case involving transboundary air pollution emanating from a smelter in Canada (Trail) and causing harm in the USA, the Legal Adviser of the US Department of State shared the view that:‘It is a fundamental principle of the law of nations that a sovereign state is supreme within its own territorial domain and that it and its nationals are entitled to use and enjoy their territory and property without interference from an outside source.’182
Again, this extreme perspective shows that – like the absolute territorial sovereignty theory – the concept of absolute territorial integrity may only be useful as a diplomatic tool, rather than being reflective of state practice. In the case at hand, the tribunal allowed the smelter to continue operating subject to a very stringent emissions regime meant to avoid unreasonable harm in the USA and the payment of compensation for any damage caused despite complying with the emissions regime. Few other countries have referred to the concept in transboundary water disputes.183
Neither of these two extreme positions therefore received universal support – for an obvious reason: watercourse states cannot be easily divided into upstream or downstream states as some countries fit into both categories (some rivers may end in a state’s territory, while others may originate from it) and other countries may be midstream states (in the case an international river flows through three or more countries). History has shown that the theories of absolute territorial sovereignty and absolute territorial integrity have been merely used as strong bargaining positions – a negotiation technique known as the ‘zerosum game’ – before a compromise agreement satisfactory to all parties was reached.184
Today, the more balanced concept of ‘limited territorial sovereignty’ is widely accepted as the foundation upon which the law of international watercourses in general, and the UNWC in particular, have evolved.185 It stipulates that all watercourse states enjoy an equal right to the utilisation of a shared water resource, and that each watercourse state has to respect the sovereignty and correlative rights of other watercourse states – i.e. that it must not exceed its own right to equitable utilisation.186
Such an approach is exemplified in a dispute concerning the River Meuse which took place in 1856. Holland protested against a Belgian diversion of water from the transboundary river into the Campine Canal as it believed this measure caused damage by reducing the navigability of the Meuse and increasing the vulnerability to flooding.187 According to the Dutch government:
‘The Meuse being a river common both to Holland and to Belgium, it goes without saying that both parties are entitled to make the natural use of the stream, but at the same time, following general principles of law, each is bound to abstain from any action which might cause damage to the other. In other words, they cannot be allowed to make themselves masters of the water by diverting it to serve their own needs, whether for purposes of navigation or of irrigation.’188
The two states settled their dispute over the Meuse with two treaties in 1863 and 1873.189 This is just one of numerous cases in which upstream states have recognised the legal rights of their lower riparians.190
The concept of limited territorial sovereignty is strongly reflected in the principle of equitable and reasonable utilisation, which can now be considered as a principle of customary international law. It aims to reconcile conflicting interests across international borders, so as to ‘provide the maximum benefit to each basin state from the uses of the waters with the minimum detriment to each.’191
One of the main advantages of the principle is that it simultaneously recognises the rights of both upstream and downstream countries. It underpins the theory of limited territorial sovereignty by entitling each basin state to a reasonable and equitable share of water resources for beneficial uses within its own territory while at the same time upholding the obligation not to deprive other basin states of their own right to equitable and reasonable utilisation.
The principle of equitable and reasonable utilisation performs two functions. Firstly, it establishes the objective to be achieved (an equitable and reasonable use), which determines the lawfulness of a use of the transboundary watercourse; and secondly, it serves an important operational function at the process level, requiring that all relevant factors and circumstances (natural and socio-economic) are taken into account in the process of balancing the needs and proposed uses of each riparian state when determining what qualifies as a legitimate – i.e. equitable and reasonable – use (see Article 6 – Factors relevant to equitable and reasonable utilisation).192
The idea that all co-riparians enjoy an equal right in the use of an international watercourse has been affirmed by the judgment of the International Court of Justice (ICJ) in the Gabcíkovo-Nagymaros Case. Here, the court held that the unilateral operation of a Slovak project on the Danube (referred to as ‘Variant C’), allowing Slovakia (at the time Czechoslovakia) to utilise between 80 and 90 per cent of the waters of the transboundary river for its exclusive benefit, represented an infringement on Hungary’s ‘basic right to an equitable and reasonable sharing of the resources of an international watercourse.’193
In order to complete the analyis of the theories of allocation it is important to mention the concept of ‘a community of interests’. The concept of a community of interests can be seen as a step beyond the theory of limited territorial sovereignty. The Permanent International Court of Justice made reference to the concept in the 1929 Territorial Jurisdiction of the International Commission of the River Oder, where it stated that:
‘This community of interest in a navigable river become the basis of a common legal right, the essential features of which are the perfect equality of all riparian states in the use of the whole course of the river and the exclusion of any preferential privilege of any one riparian state in relation to the others.’194
The River Oder case was referred to more recently in the Gabcíkovo-Nagymaros case where the International Court of Justice stated that:
‘Modern development of international law has strengthened this principle for non-navigational uses of international watercourses as well, as evidenced by the adoption of the Convention of 21 May 1997 on the Law of the Non-navigational Uses of International Watercourses by the United Nations General Assembly.’195
The Court therefore went on to conclude that:
‘Czechoslovakia, by unilaterally assuming control of a shared resource, and thereby depriving Hungary of its right to an equitable and reasonable share of the natural resource of the Danube … failed to respect the proportionality which is required by international law’.196
In reference to the above statements McCaffrey claims that, ‘the concept of community of interest can function not only as a theoretical basis of the law of international watercourses but also as a principle that informs concrete obligations of riparian states, such as that of equitable utilisation.’197 However, McCaffrey also goes on to claim that the precise legal implications of the community of interests concept are less than completely clear:
‘The legal import of the doctrines of absolute territorial sovereignty and integrity is clear enough; that of limited territorial sovereignty, while not so stark, is also fairly well understood. How, then, is the notion of community of interest different from these theories? It is one thing to say, as the Permanent Court did in the River Oder case, that one state may not prevent other states from navigating on an international watercourse because they all enjoy a community of interest in it. It is something quite different to maintain that the community of interest in an international watercourse allows one state to prevent another state from diverting water from it, for example. While all riparian states (and other states, as well) may have an interest in navigating on the whole course of a river can it be said that all riparian states have an interest in the whole course of a river – i.e. the entire watercourse system – insofar as non-navigational uses are concerned? For example, would a state that was not adversely affected by a co-riparian state’s diversion have legal grounds for protesting the diversion, absent an applicable agreement? There would seem to be little doubt that the answer would be in the negative. Such a right is supported neither in state practice nor in the writings of commentators. Therefore, the concept of community of interest must have another meaning in the case of nonnavigational uses.’198
In this regard, some commentators have sought to equate the community of interests concept with that of ‘common management.’199 Caflisch argues for the merits of ‘denationalising’ international watercourses, shifting the emphasis from individual states to joint organisation.200 However, the latter commentator also observes that, ‘while it is clear that a condominium could be established by treaty, one cannot maintain that, by virtue of the rules of customary law, the whole of an international watercourse, including its resources, forms a condominium.’201
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