Uruguay River

The Uruguay River (known as Río Uruguay in Spanish and Rio Uruguai in Portuguese) is a significant waterway in South America. Running north to south, it helps define the borders of Brazil, Argentina, and Uruguay, dividing several Argentine provinces in the Mesopotamia region from the other two nations. In Brazil, it flows between the states of Santa Catarina and Rio Grande do Sul. It marks the eastern edge of Argentina’s Misiones, Corrientes, and Entre Ríos provinces, and forms the western boundary of Uruguay’s Artigas, Salto, Paysandú, Río Negro, Soriano, and Colonia departments.

The river’s name comes from Spanish settlers’ adaptation of a Guaraní word used by local inhabitants. Possible meanings include “the river of the uru” (a native bird) or “the river of the uruguá” (a native snail, Pomella megastoma).

Stretching roughly 1,838 kilometers (1,142 miles), the Uruguay begins in Brazil’s Serra do Mar range, where the Canoas and Pelotas rivers meet at about 200 meters (660 feet) above sea level. In its upper course, the river cuts through rugged terrain, creating rapids and waterfalls, and is not navigable through Rio Grande do Sul. A unique feature is a submerged canyon formed during the Ice Age, when a drier climate made the river narrower. This canyon reaches depths of up to 100 meters (330 feet) below the riverbed and is one-eighth to one-third as wide as the river itself. It is visible in only two spots, including the Moconá Falls (also called Yucumã Falls). These falls are unusual: they run parallel to the river, not perpendicular, and are not visible for about 150 days each year, appearing more like rapids during that time. They stand 10 to 12 meters (33 to 39 feet) high and stretch between 1,800 and 3,000 meters (5,900 to 9,800 feet) wide, located 1,215 kilometers (755 miles) from the river’s mouth. The Brazilian side of the falls is protected by the 17,491-hectare (43,220-acre) Turvo State Park, established in 1947.

Together with the Paraná River, the Uruguay forms the Río de la Plata estuary. It becomes navigable near Salto Chico. Its main tributary is the Río Negro, which originates in southern Brazil and flows through Uruguay for 500 kilometers before joining the Uruguay River, 100 kilometers north of the Uruguay’s confluence with the Río de la Plata at Punta Gorda, in Uruguay’s Colonia Department. Five international bridges cross the river: from north to south, the Integration Bridge and Paso de los Libres-Uruguaiana International Bridge (between Argentina and Brazil), and the Salto Grande Bridge, General Artigas Bridge, and Libertador General San Martín Bridge (between Argentina and Uruguay). The river’s drainage basin covers 365,000 square kilometers (141,000 square miles). Its main economic use is hydroelectricity, with dams including the Salto Grande Dam and, upstream in Brazil, the Itá Dam.

Argentina and Uruguay once clashed over pulp mill construction on the river. European companies ENCE and Botnia proposed building cellulose plants at Fray Bentos, Uruguay, across from Gualeguaychú, Argentina. A 1975 treaty required joint agreement on river matters, and Argentina claimed Uruguay violated it. Argentina also argued that Botnia was polluting the river’s fish and environment, while Uruguay maintained the plant released few toxins. Starting in April 2005, residents of Gualeguaychú and others protested, fearing pollution. By early 2006, the dispute became a diplomatic crisis, prompting one company to relocate its project 250 kilometers (160 miles) south. From December 2005, Argentine protesters intermittently blockaded international bridges linking Entre Ríos to Uruguay, disrupting trade and tourism. In 2006, Argentina took the case to the International Court of Justice, which held hearings until October 2009. In 2010, the court ruled that while Uruguay failed to inform Argentina about the construction, the mills did not pollute the river, so closing the remaining plant was unjustified. Later that year, both countries formed a joint commission to coordinate river activities.