The Olszewski-tube was put into Lake Piburg in the 1970s in order to transport oxygen-free, sulphurous deep groundwater enriched with nutrients out of the lake. The removal of these substances is important for the long-term preservation of a stable echo system in the lake, as otherwise natural eutrophication and thus destabilisation with accompanying silting process would take place. After in the winter of 2013/14, the flow dropped dramatically from 6 litres/sec. to 2 litres/sec., it was found that there was a sharp bend in the tube. As part of a project (2014) the Olszewski-tube was repaired.