Río Negro (Uruguay)

The Río Negro (Black River) is the most important river in Uruguay. It is a left tributary of the Uruguay river. It starts in southern Brazil and flows west across the entire width of Uruguay to the Uruguay River.

The course of the Río Negro across Uruguay effectively divides the south of the country from the north.

Geography
The Río Negro is  long. Its drainage basin covers , most of it in territory of Uruguay; only  are in Brazil.

Its average yearly discharge (volume of water which passes through a section of the river per unit of time) is  (70 years) at the Palmar dam,  to the east of the city of Mercedes, Soriano department.

Average monthly discharge (m3/s) at Palmar

Course
The Río Negro starts in the Bagé municipality, Rio Grande do Sul state, Brazil. It flows from northeast to southwest through Uruguay and divides the country in two parts: the northern part with 6 departments and the southern part (slightly larger) with the 13 remaining departments.

Its course forms the border of the departments:
 On its northern (right) side: Rivera, Tacuarembó and Río Negro.
 On its southern (left) side: Cerro Largo, Durazno, Flores and Soriano.

At its end, to the south of the city of Fray Bentos in the Río Negro department, the Río Negro flows into the Uruguay river as a left tributary. The river has many meanders along its course and three hydroelectric dams has been built on this river that form three artificial lakes (or reservoirs in this case), from northeast to southwest:
 Rincón del Bonete Reservoir, also called the Gabriel Terra Reservoir or the Río Negro Reservoir;
 Baygorria Dam; and the
 Palmar or Constitution Dam.

The main cities along the river:
 Tacuarembó department
 Paso de los Toros.
 San Gregorio de Polanco.
 Soriano department
 Mercedes, capital of the department.
 Villa Soriano, one of the oldest towns of Uruguay; it is near the mouth of the Río Negro river.

Main tributaries
The main tributaries of the Río Negro are:

Left tributaries:
 Yí - 210 km.

Right tributaries:
 Tacuarembó - 260 km.

Gallery

Related pages
 List of rivers of France

 References 

Category:Rivers of Uruguay
Category:Rivers of Brazil