Article 25(3) defines ‘regulation’ as meaning ‘the use of hydraulic works or any other continuing measures to alter, vary or otherwise control the flows of the waters of an international watercourse.’ Such measures might include ‘dams, reservoirs, weirs, canals, embankments, dykes, and river ban fortifications’. 390 A similar approach is adopted by the ILA, which define regulation as ‘continuing measures intended for controlling, moderating, increasing and otherwise modifying the flow of the waters in an international watercourse for any purpose; such measures may include storing, releasing and diverting of water by means such as dams, reservoirs, barrages and canals’391.

As well as defining the scope of regulation activities, Article 25 also sets out the obligations incumbent upon states, which can be seen as an extension of the requirements found elsewhere in the Convention, such as the substantive requirements under Article 5 and Article 7 to utilise an international watercourse in an equitable reasonable manner, and under Article 8 the obligation to cooperate. Article 25(1) therefore sets out the obligation that ‘where appropriate’, states should cooperate in the regulation of international watercourses. The importance of such cooperation is clearly spelled out by the ILA which states:

‘The regulation of a border-river is hardly possible without the co-operation or consent of the state on the other side of the river. As regards watercourses crossing state borders, efficient regulation of activities likewise require the close co-operation of the states concerned. There are often important reasons which speak in favour of a joint venture but also in other cases it is obvious that legal questions relating to the regulation of an international watercourse must be settled by an agreement between the states concerned.’392

The ILA also points out that, ‘planning and the realisation of regulation may be a very complicated undertaking. Different kinds of information, particularly meteorological and hydrological data, must be collected, technical possibilities and economic factors must be evaluated, and the legal conditions of the undertaking must be cleared up and settled.’393

Clearly, within an international watercourse, such activities require a strong level of cooperation between watercourse states. Cooperative activities are likely to include:

(i) the collection and exchange of data;

(ii) the preparation and mutual exchange of surveys, investigations and studies;

(iii) planning and designing of relevant measures;

(iv) operation and maintenance of works;

(v) sharing expenses; and

(vi) forecasting and communication of relevant hydrological data.394 

However, the ILC is keen to point out that the use of the term ‘where appropriate’ implies that states are not under a strict obligation to identify needs and opportunities for regulation, but rather to ‘respond to those that exist.’395

Consistent with Article 5(2) of the UN Watercourses Convention any form of cooperation between watercourse states will be agreed on an equitable basis. Where the construction and maintenance of regulation works has taken place, the costs and benefits of such activities will therefore be allocated on an equitable basis. If one state derives all the benefits from regulation, on the basis of equity, they should bear the full costs.396

387 S Bogdanovic (ed), International Law of Water Resources – Contribution of the International Law Association (1954-2000), at 253.

388 See Section 20.1.

389 AE Utton and J Utton, ‘The International Law of Minimum Stream Flows’ (1999) 10 Colorado Journal of International Law and Policy 7, 36.

390 1994 Draft Articles at 127.

391 S Bogdanovic (ed), International Law of Water Resources – Contribution of the International Law Association (1954-2000), 274.

392 Ibid, 271.

393 Ibid, 271.

394 Ibid, 280.

395 1994 Draft Articles at 126.

396 Ibid, 127.

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