The combined approach—a challenge for border crossing water quality issues in Austria

Is it sufficient to meet threshold values downstream of a discharge, even if this leaves no more space for future development? Is it simply bad luck for a downstream country, if threshold values are filled up at the border and there is no more space for additional emissions? If not: what are the criteria to distribute acceptable emissions between countries and regions? Who pays according to the “polluter pays” principle in a case, if several polluters contribute to the pollution, but the most cost-effective measures to reach the good status concern only some of the emitters/enterprises? There are little experiences with those and other related questions in Austria and many other EU-member states. This contribution intends to discuss these issues based on actual problems and would like to raise awareness for several of these unsolved questions.