The Rur or Roer ( ; Dutch and , , ; ) is a major river that flows through portions of Belgium, Germany and the Netherlands. It is a right (eastern) tributary to the Meuse (). About 90 percent of the river's course is in Germany. It is not to be confused with the rivers Ruhr and Röhr, which are tributaries of the Rhine in North Rhine-Westphalia. Geography The Rur rises in the High Fens, near the high Signal de Botrange in Belgium at an elevation of above sea level. South of Monschau it flows into Germany, through North Rhine-Westphalia. It flows first through the northern part of the Eifel mountains. After it reaches the Rur Reservoir, the second-largest artificial lake in Germany. After approximately it flows into the Netherlands, and at its mark it flows into the river Meuse in the town of Roermond. Major tributaries of the Rur include the Inde and the Wurm. The towns along the Rur are Monschau, Heimbach, Nideggen, Düren, Jülich, Linnich, Hückelhoven, Heinsberg (all in Germany) and Roermond (Netherlands). In the 1960s and 1970s, the northern part of the Rur was heavily polluted by the tailings of many German coal mines. Neither fish nor other organisms could be found, and it was dangerous to swim in the river. Foam flakes regularly flooded parts of the city of Roermond. After the closure of the mines, the waste water treatment in Germany and the Netherlands greatly improved. Only the lower part of the river is still contaminated. The water in the upper part of the river is so clean that trout and more than 30 species of fish are back. After an absence of 125 years, salmon returned to the Rur in 2004. Tributaries Ellebach Inde Kall Malefinkbach Merzbach Wurm Olef Urft History During the Middle Ages the valley of the Rur lay mostly within the Duchy of Jülich. In 1795, until 1814, during which time the area was part of the French Republic and Empire, it gave its name to the French département of the Roer. The Rur represented an important front in the Allied push towards Germany at the end of the Second World War. A fortified area known as the Roer Triangle, formed by the towns of Roermond and Sittard, in the Netherlands, and Heinsberg in Germany, was the scene of heavy fighting at the beginning of 1945. Operation Blackcock was the