Most of the border of the department with Durazno Department in the north is formed by the Yí River, with many of its tributaries flowing in the north part of the department. From east to west, these are the streams: Arroyo del Pescado, Arroyo Molles del Pescado, Arroyo Illescas, Arroyo Sauce, Arroyo Mansavillagra, Arroyo Timote, Arroyo Molles del Timote, Arroyo de Castro, Arroyo Sarandí and Arroyo Sauce de Villaneuva, which also forms the border near the city of Durazno. The border then follows Arroyo Batoví a tributary of Arroyo Maciel, the later forming big part of the border of the department with Flores Department to the west and is itself a tributary of Yí River.