Why are coastal species turning up in a German river? In parts of the Werra, salt levels are more than 20 times higher than normal after decades of potash mining pollution. Many freshwater species have vanished, replaced by plants and animals that thrive in salty conditions. But further upstream, scientists have found around 70 species in clean water, offering a glimpse of what the river could become again. With the EU's 2027 water quality deadline approaching, the battle to restore the Werra is far from over.