PULP MILLS (JUDGMENT) 76 1975 Statute, which places the Parties under an obligation to co-ordinate through CARU the necessary measures to avoid changing the ecological balance of the river. Argentina asserts that the discharges from the Orion (Botnia) mill altered the ecological balance of the river, and cites as examples the 4 February 2009 algal bloom, which, according to it, provides graphic evidence of a change in the ecological balance, as well as the discharge of toxins, which gave rise, in its view, to the malformed rotifers whose pictures were shown to the Court. 182. Uruguay considers that any assessment of the Parties’ conduct in relation to Article 36 of the 1975 Statute must take account of the rules adopted by CARU, because this Article, creating an obligation of co-operation, refers to such rules and does not by itself prohibit any specific conduct. Uruguay takes the position that the mill fully meets CARU requirements concerning the ecological balance of the river, and concludes that it has not acted in breach of Article 36 of the 1975 Statute. 183. It is recalled that Article 36 provides that “[t]he parties shall coordinate, through the Commission, the necessary measures to avoid any change in the ecological balance and to control pests and other harmful factors in the river and the areas affected by it”. 184. It is the opinion of the Court that compliance with this obligation cannot be expected to come through the individual action of either Party, acting on its own. Its implementation requires co-ordination through the Commission. It reflects the common interest dimension of the 1975 Statute and expresses one of the purposes for the establishment of the joint machinery which is to co-ordinate the actions and measures taken by the Parties for the sustainable management and environmental protection of the river. The Parties have indeed adopted such measures through the promulgation of standards by CARU. These standards are to be found in Sections E3 and E4 of the CARU Digest. One of the purposes of Section E3 is “[t]o protect and preserve the water and its ecological balance”. Similarly, it is stated in Section E4 that the section was developed “in accordance with . . . Articles 36, 37, 38, and 39”. 185. In the view of the Court, the purpose of Article 36 of the 1975 Statute is to prevent any transboundary pollution liable to change the ecological balance of the river by co-ordinating, through CARU, the adoption of the necessary measures. It thus imposes an obligation on both States to take positive steps to avoid changes in the ecological balance. These steps consist not only in the adoption of a regulatory framework, as has been done by the Parties through CARU, but also in the observance as well as enforcement by both Parties of the measures adopted. As the Court emphasized in the GabčíkovoNagymaros case : “in the field of environmental protection, vigilance and prevention are required on account of the often irreversible character of damage 66