Artificial lakes
Dhünn is a 40 km (25 mi)-long river located in North Rhine-Westphalia, Germany. Its main source is near Wipperfürth in the Bergisches Land area. It runs in a south-westerly direction, and its mouth into the river Wupper is near Leverkusen, appr. 10 km (6.2 mi) north of Cologne.
By diverting the river bed of the Dhünn around the Sensenhammer weir in April 2010, it was declared the first barrier-free river in North Rhine-Westphalia. This means that the 24 km (15 mi)-long stretch of the river from the mouth into the Wupper to the Großen Dhünn dam is accessible without obstacles for fish and microbes. Fish can now migrate again freely to their spawning grounds.
