Salzach was a river that flowed through Salzburg in Austria. (PROSE: Do You Believe in the Krampus?)
Shortly after Wolfgang Amadeus Mozart's birth in 1756, Antonio Salieri tried to drown him to prevent Mozart from eclipsing him as a composer. The Seventh Doctor talked Salieri out of it. (PROSE: The Tramp's Story)
On 5 December, Bruno Werner planned to drown himself in Salzach so that his insurance would be enough to pay the rent for his wife Antonia and daughter Maria. The Eighth Doctor talked Bruno out of it, but not before Maria wished the Krampus to be real and punish their landlord Mr Shafranek. Her wish was granted by Artron, one of the consequences of which was that water in Salzach started boiling. (AUDIO: Better Watch Out / Fairytale of Salzburg)