Ruhr (river)
The Ruhr is a river in western Germany that falls from about 670 meters above sea level to only 17 meters over a course of 219 km. That slow descent carries it out of the hills of the Sauerland and down toward the lower Rhine. Along the way, this river of modest size drew in an occupying army and, later, a bombing raid. It also lost much of its fish life. Why did a river like this matter so much to its country? What did its banks hold that two armies wanted to control or destroy? And can a waterway reworked this thoroughly ever be made passable for migrating fish again?
The Ruhr begins near the town of Winterberg, in the mountainous Sauerland region of North Rhine-Westphalia. It ends in the municipal area of Duisburg, where it joins the Rhine from the east as a right-bank tributary. Near its mouth at Mülheim, the river carries an average of 79 cubic meters of water per second. That puts it on a par with the Ems in northern Germany and with the Thames in the United Kingdom. In its upper reaches, the Ruhr first passes Meschede, Arnsberg, Wickede, Fröndenberg, Holzwickede, Iserlohn, and Schwerte. After that, it marks the southern limit of the Ruhr area, flowing past Hagen, Dortmund, Herdecke, Wetter, Witten, Bochum, Hattingen, Essen, Mülheim, and Duisburg. Dozens of streams feed it on the way. The Lenne and the Volme join from the left bank, along with smaller waters such as the Hönne and the Elpe. From the right bank come the Wanne and the Möhne. That last name would become famous far beyond Germany for a reason that had nothing to do with fishing or farming.
In 1923, French forces moved into the Ruhr area. The region was then Germany's primary industrial area, and most of the country's factories stood there. The Weimar Republic had failed to keep up its reparations payments after World War I, and the occupation was the response. Germans answered with passive resistance, and production in the factories ground to a halt. The standstill made the German hyperinflation crisis worse. The occupation lasted until 1924. A later war would bring a very different kind of attack on the same factories.
During World War II, two dams on the Ruhr became the targets of Operation Chastise. They were the Möhne Dam and the Sorpe Dam. Planners hoped that breaking them would flood the valley below and seriously hurt the German industries that depended on it. To do the job, special "bouncing bombs" were developed for the mission. The raid became the subject of a book published in 1951. A film adaptation, The Dam Busters, followed in 1955 and was popular with audiences. Not every dam on the river carries such a history, and the quieter ones now serve a gentler purpose.
Baldeneysee, in Essen-Werden, is the largest of the five reservoirs on the Ruhr. It covers 2.64 square kilometers behind a weir 8.5 meters high. Hengsteysee lies between Dortmund and Hagen and spreads over 1.36 square kilometers, with a 4.5-meter weir. Harkortsee sits between Herdecke and Wetter. It covers 1.37 square kilometers and has a weir of 7.8 meters. Kemnader See, between Witten and Bochum, covers 1.25 square kilometers and has the lowest weir of the group, at just 2 meters. The smallest is Kettwiger See in Essen-Kettwig, with 0.55 square kilometers and a 6-meter weir. People often use these lakes for leisure. For migrating fish, though, every one of these weirs is an obstacle.
Through the 19th and 20th centuries, factories along the Ruhr drew on the river as cooling water. They also sent industrial discharge back into it, and the river became heavily contaminated. Large sections were straightened, which changed the habitat of the river and its shores. Fish suffered, especially the brook trout and its relatives among the salmonids. The river was also cut up by dozens of smaller and larger dams. These largely blocked migratory species such as salmon and the European eel from climbing or descending the river as their life cycles require. Salmon have not been seen in the Ruhr in decades. Eel stocks have dwindled. Both eel and brook trout now depend heavily on the release of juveniles raised for conservation. A regional authority eventually decided to reverse part of this damage.
Since 2013, the district government of Arnsberg has been investing heavily in restoring the Ruhr and its surroundings. The European Union has funded part of the work through grants. A central aim is to let fish move naturally along the whole river again. Crews do this by removing barriers such as dams or by adding bypasses around them. In some sections, they also widen the river bed substantially. A wider bed makes the water shallower and slows its flow. That helps native fish, insects, and other life reproduce naturally. Two sections are complete, in Wickede and in Witten, and two more projects are underway. Eighteen further projects remain in planning, and until they are built the river is not fully passable for migratory fish.
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Common questions
Where does the Ruhr river start and end?
The Ruhr begins near the town of Winterberg in the Sauerland region at about 670 meters elevation. It flows into the lower Rhine at about 17 meters elevation in the municipal area of Duisburg.
How long is the Ruhr river?
The Ruhr is 219 km long. Its average discharge at Mülheim near its mouth is 79 cubic meters per second, comparable to the Ems or the Thames.
Which cities does the Ruhr river flow through?
The Ruhr passes Meschede, Arnsberg, Hagen, Dortmund, Witten, Bochum, Hattingen, Essen, Mülheim, and Duisburg, among other towns. In its lower course it marks the southern limit of the Ruhr area.
What was Operation Chastise on the Ruhr?
Operation Chastise was a World War II raid on the Möhne Dam and the Sorpe Dam. Special bouncing bombs were developed to flood the valley and hurt German industry. The story was told in a 1951 book and the 1955 film The Dam Busters.
Why did French forces occupy the Ruhr area in 1923?
French forces occupied the Ruhr area from 1923 to 1924 because the Weimar Republic had failed to continue World War I reparations payments. German passive resistance halted factory production and worsened the hyperinflation crisis.
Why are there no salmon in the Ruhr river?
Dozens of dams largely blocked salmon and European eel from migrating along the Ruhr, and industrial pollution and river straightening harmed fish habitat. Salmon have not been observed in the river in decades.
What is being done to restore the Ruhr river?
Since 2013 the district government of Arnsberg has run renaturation projects, partly funded by the European Union. They add or improve bypasses around barriers and widen the river bed to help fish migrate and reproduce. Two sections, in Wickede and Witten, are complete.
All sources
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