It was said that long ago, the Saal River was haunted by the souls of children stolen by nixies.  Nixies are female water spirits, famous for inhabiting pools and rivers. 

These stolen souls sang along the banks of the river, and occasionally traveled to the markets to spend time with the living.  

They could be recognized by their clothing; the bottom hems were always wet, and left a trail of water wherever they walked.

This story was recorded by Jacob and Wilhelm Grimm, in German Legends.  To read the original German, visit:  Google Books: Die Elbjunfer und das Saalweiblein To read an English translation, visit:  The Nixie Changlings from the Saal River, D.L. Ashliman