According to current federal legislation (Waters Protection Act and Ordinance), a watercourse corridor must be designated around lakes and along rivers and streams. The cantons are obliged to define the space requirements for surface waters that are necessary to guarantee the natural functions of water bodies, including their shores and banks (e.g. habitat for plants and animals, buffers against water pollution) and protection against flooding and for the viability of long-term water use (e.g. electricity production and recreation).

Together with the authorities, TBF has drawn up guidelines for defining watercourse corridors in the canton of Appenzell Innerrhoden and has specified watercourse corridors for the entire canton.