3. Watercourse States shall, at the request of any of them, consult with a view to establishing lists of substances, the introduction of which into the waters of an international watercourse [systom] is to be prohibited, limited, investigated or monitored. e 24 Watercourse States shall take all measures necessary to prevent the introduction of species, alien or ned, into an international wstercourse [system] which may have effects detrimental to the ecosystem of the international wat.ercoursa [system] resulting in appreciable harm to other watercourse States. */This paragraph which clenls with the definition of pollution may be moved up to article 1 on [Use of terms 1. 145Watercourse Gtates shall, individually or jointly, take all measures with respect to an international watercourse [system] that are necessary to protect and preserve the marine environment, including estuaries, taking into account generally accepted international rll)os and standards. PART V HARMFUL CONDITIONS AND EMERGENCY SITUATIONS Watercourse States shall, individually or jointly, take all appropriate measures to prevent or mitigate conditions that may be harmful to tether watercourse States, whether resulting from natural causes or human conduct, such as flood qr ice conditions, water-borne diseases, siltation, erosion, salt-water intrusion, drought or desertification. 1. For the purposes of the present draft art- icle, “emergency” means a situation that causes, or poses an imminent threat of causing, serisus harm to watercourse jtates or other States and that results suddeniy from natural causes, such as floods, the breaking up of icy, landslides or earthquakes, or from human conduct as for example in the case of industrial accidents. 51 2. A watercourse State shall, without delay and by the most expeditious means available notify other potentially affected States and competent international organisations of any emergency originating Witkii? its territor. . 3. A watercourse State within whose territory an emergency originates shall, in m:-oyart(:ion with potentially affected States ancl,
**Analysis**
The text discusses the protection and preservation of an international watercourse system, including measures to prevent pollution, prevent or mitigate harmful conditions, and respond to emergencies. This suggests that the text is focused on environmental issues and the management of natural resources.

**Category**
Natural resources and environment, International relations