Quaraí RiverThe Quaraí or Cuareim River is a tributary of the Uruguay River.LocationThe river rises in the Coxilha de Santana, an area of low-lying hills, and runs westward to join the Uruguay River. It forms the boundary between Uruguay on the south and Rio Grande do Sul state of Brazil on the north.Border disputeThere is a long-standing and unresolved border dispute between Uruguay and Brazil along part of Quaraí River. However, this is not seen as a politically disturbing issue between the two countries, which have close and friendly diplomatic relations and strong economic ties. So far, the disputed areas have been effectively under Brazilian control.