Río Negro Department (, ) is a department of the northwestern region of Uruguay. It has an area of and a population of 54,765. Its capital is Fray Bentos. It borders Paysandú Department to the north, Tacuarembó Department to the east, Durazno Department to the southeast, Soriano Department to the south and has the Río Uruguay flowing at its west, separating it from Argentina. History The first division of the Republic in six departments happened on 27 January 1816. Later in that year two more departments were formed. At the time, Paysandú Department included all the territory north of the Río Negro, which included the current departments of Artigas, Rivera, Tacuarembó, Salto, Paysandú and Río Negro. On 17 June 1837 a new division of Uruguay was made and this territory was divided in three parts. In the new division, Paysandú Department also included the current department of Río Negro, until it was split from it in 1868. Geography The Río Negro flows along the southern border of the department, forming the natural border with the departments of Durazno to the southeast and Soriano to the south. Tributary streams (arroyos) to the Río Negro, flow through most of the department. From east to west, these are: Arroyo Salsipuedes Grande, which forms part of the border with Tacuarembó Department to the east, while its tributary Arroyo Juan Tomas forms a little part of the northeast border with Paysandú Department, Arroyo Tres Árboles with its tributary Arroyo Islas de Argüelles, Arroyo Rolón, Arroyo Grande, with its tributaries Arroyo de las Flores and Arroyo Averías Grande, Arroyo Don Esteban Grande, Arroyo Sanchez Grande, with its tributaries Arroyo Sanchez Chico and Arroyo Coladeras. The Río Negro discharges into Río Uruguay about southwest of Fray Bentos. Notable along its course in respect to this department are two hydroelectric dams: the Rincón de Baygorria Dam, forming the Baygorria Reservoir and the Constitución Dam (also known as Palmar Dam), forming the Paso de Palmar Reservoir. In both cases, the power installations are situated on the neighbouring departments of Durazno and Soriano respectively. A big part of the north border with Paysandú Department is formed by Arroyo Negro with two of its tributary streams flowing through the northwest of the department. These are: Arroyo Gutiérez Grande and Arroyo Bellaco. It discharges into Río Uruguay about north of San Javier and opposite the city of Argentina Concepción del Uruguay, forming