NM23-721-515 Rio Negro, Argentina Winter/Spring 1997 The valley of the Rio Negro near the small agricultural city of Choele Choel, is at the apex of the three white lines. Other roads, railroads, and pipelines can be seen traversing the image. The valley sets nearly 350 feet (107 meters) lower than the surrounding plateau. The Rio Negro flows generally eastward across the plateau and empties into the Atlantic Ocean. Fed by glaciers and snowmelt from the Andes Mountains to the west, the Rio Negro provides irrigation water for the agricultural fields within the valley.