|Land-based pollution is considered to be the single most important cause of marine pollution, contributing an estimated 80 percent of all marine pollution.364 Various land-based sources may cause pollution, including municipal, industrial and agricultural practices. These sources may reach the marine environment from the coast, the atmosphere, and via international watercourses.365 Economic development, coupled with a greater scientific understanding of the linkages between freshwater and marine ecosystems, has meant that there is now a greater recognition of the fact that the status of the marine environment is largely dependent on the behaviour of states that may not even belong to a particular maritime region.366 Those states may be land-locked and not necessarily affected by the marine pollution.367
Article 23 seeks to address this situation by providing a bridge between two legal regimes, the law of international watercourses and the law of the sea.368 In so doing, the Article complements provisions contained in various treaties dealing with marine environments. Such treaties include the UN Convention on the Law of the Sea, which requires states to ‘adopt laws and regulations to prevent, control and reduce pollution of the marine environment from land-based sources, including rivers, estuaries, pipelines and outfall structures, taking into account internally agreed rules, standards and recommended practise and procedures’.369 The latter Convention goes on to stipulate that ‘states, acting especially through competent international organisations or diplomatic conference, shall endeavour to establish global and regional rules, standards and recommended practices and procedures to prevent, reduce and control pollution of the marine environment from land-based sources’.370
While there is no legally-binding global instrument dealing exclusively with land-based pollution, a nonbinding set of recommendations and guidelines have been adopted by UNEP’s Global Programme of Action for the Protection of the Marine Environment from Land-based Activities (GPA) (see figure 20.6).371 At the regional level a number of legally-binding instruments deal with land-based sources of pollution. While most regional regimes only include coastal states within their membership, some allow for non-coastal states to become party.372 In its reference to taking into account, ‘generally accepted rules and standards relating to the protection and preservation of the marine environment’, Article 23 seeks to ensure that watercourse state practice reflects these global and regional instruments. In reference to the obligation to ‘take into account’, Tanzi and Arcari comment that the obligation, ‘is not to impose on watercourse states the straightforward application of rules and standards drawn from different agreements, but, more modestly, that of ensuring that the measures that states are planning or implementing on an international watercourse under Article 23 of the Convention be at least consistent with the pertinent rules and standards governing the protection and preservation of the marine environment.’373 Additionally, through the use of the term ‘take all measures… that are necessary to protect and preserve’, Article 23 adopts the same standard of responsibility contained, and discussed, under Article 7, namely that of due diligence (see Glossary of Terms). What may be deemed as appropriate can be gleaned from the global and regional instruments noted above. Measures that might be considered ‘appropriate’ could therefore include environmental impact assessments, monitoring, notification, information exchange and consultation, scientific and technical cooperation, assistance to developing countries, development of control strategies, and so forth.374
The same standards to protect and preserve are also included, which would incorporate the precautionary approach (see Glossary of Terms). Additionally, the same requirement as contained in Article 20 is included, namely to cooperate, ‘where appropriate’, with other states. 375 However, a slight variation occurs in reference to ‘other states’ rather than ‘watercourse states’. This deviation reflects that scenario whereby states sharing a particular marine environment, but not necessarily the same watercourse, may find it advantageous to cooperate.
The ILC Commentary makes it clear that the obligation set forth in this Article is not an obligation to protect the marine environment in the strict sense of the term, but rather a more precise one to take measures with respect to an international watercourse that are necessary to protect the marine environment.376 The latter commentary also makes it clear that the requirement in Article 23 is separate from the obligations contained in Articles 20-22. Activities that cause pollution to an estuary may therefore not meet the threshold of significant harm, as stipulated for in Article 21, but could still be deemed to have breached the requirement contained in this article to protect and preserve an estuary.377
The Global Programme of Action for the Protection of the Marine Environment from Land-based Sources recommends that states:
A. Identify and assess problems related to the:
B. Establish priorities for action by assessing the five factors above, reflecting the relative importance of impacts upon food security, public health, coastal and marine resources, ecosystem health, and socio-economic benefits, including cultural values in relation to
C. Set management objectives for priority problems for source categories and areas affected on the basis of established priorities. D. Identify, evaluate and select strategies and measures to achieve these objectives. E. Develop criteria for evaluating the effectiveness of strategies and measures.
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