Laguna Merin

The Merín Lagoon (in Portuguese, Lagoa Mirim) is an extensive freshwater lagoon, with an area of 3750 km², located on the border between Brazil (Rio Grande del Sur state) and Uruguay. Its name derives from the Tupi-Guaraní word "mi´rí", which means "small."

Generalities

Although it is not considered a coastal lagoon per se, given its distance in the interior of the continent, the Merín lagoon is separated from the Atlantic Ocean by a sandy and partially sterile isthmus. The Mangueira lagoon is located on said isthmus and is part of the same hydrographic basin.

Laguna Merín has no direct connection to the Atlantic, but the Río Grande, a tidal channel about 39 km long that connects Laguna de los Patos to the Atlantic, offers an entrance to the navigable inland waters of both lagoons and several small ports. Both lagoons are remains of an ancient coastal depression enclosed by sandy beaches, formed by the combined action of wind and ocean currents.

The main tributaries from Uruguayan territory are the Cebollatí and Tacuarí rivers and, on the border between both nations, the Yaguarón (in Portuguese: Jaguarão). The river The San Gonzalo channel connects this lagoon with the Patos lagoon, an even larger lagoon, lagoon type, connected to the Atlantic Ocean.

The waters of Laguna Merín were sweet, with intermittent intrusions of brackish water from Laguna de los Patos through the San Gonzalo canal, but currently the waters of Laguna Merín are sweet due to the construction of the Centurião lock. This lock was built in 1977 with the objective of preventing the intrusion of sea water into Laguna Merín, and thus guaranteeing a reserve of drinking water for the cities of Río Grande and Pelotas, as well as preventing brackish water from damaging crops. rice fields located around the lagoon. The lock also helps prevent flooding.

The shores of the lagoon are characterized by their extensive wetlands, highlighting the Bañado de Taim, declared a world heritage site by UNESCO.

The lagoon basin extends through both countries and its economy is fundamentally based on livestock. However, the cultivation of rice is very important, taking advantage of the conditions favorable to the development of that cereal. Tourism is also an important source of resources. At various points along its shores there are places for bathing with shallow sandy beaches.

History

On July 7, 1977, the Treaty of the Laguna Merín Basin was signed in Brasilia. The Uruguayan-Brazilian Mixed Commission for the Development of the Laguna Merín Basin (CLM) is the body in charge of ensuring compliance with the agreement. The CLM has a headquarters in the department of Treinta y Tres and another in Porto Alegre.