Argentina–Uruguay border

Sharing out the islands

The Uruguay River and the Río de la Plata have been treated as the boundary since the preliminary peace convention of 27 August 1828, but no treaty drew an exact line in the 19th century. A 1916 treaty that would have divided the river’s islands by the main channel was never ratified, and in 1938 the two countries agreed to keep the status quo.^[1]

A treaty signed at Montevideo on 7 April 1961 finally fixed the line from Brasilera Island to the parallel of Punta Gorda; in its upper section it follows the middle of the riverbed, bending where necessary to leave named islands to each side, as far as the planned Salto Grande dam. A treaty of 19 November 1973 continued the line into the Río de la Plata. Its line places Martín García island on the Uruguayan side, although the treaty specifically keeps the island under Argentine jurisdiction.^[1]

“the boundary shall follow the centre line of the present bed of the river”^[1]

The pulp mill case

Under a 1975 Statute of the River Uruguay the two countries manage their shared stretch jointly. In 2006 Argentina took Uruguay to the International Court of Justice, saying it had authorised two pulp mills on the river without the required notice and consultation, and that they threatened the river. In late 2006 groups of Argentine citizens blockaded an international bridge over the river, and Uruguay asked the court to order Argentina to end it. The court declined to order provisional measures for either side.^[2]

In its judgment of 20 April 2010 the court found that Uruguay had breached its procedural obligations by not informing the river commission or Argentina, but that there was no conclusive evidence that the Orion (Botnia) mill had harmed the river in breach of Uruguay’s substantive obligations.^[2]