"Were there other commonly used forms of travel by river?"

Yes, there were: [Treideln][1], [(timber) rafting][2], and [rowing][3]. 


  [1]: http://translate.google.de/translate?sl=de&tl=en&js=n&prev=_t&hl=de&ie=UTF-8&layout=2&eotf=1&u=http://de.wikipedia.org/wiki/Treideln
  [2]: http://en.wikipedia.org/wiki/Timber_rafting
  [3]: http://en.wikipedia.org/wiki/Watercraft_rowing