Discussion of an environment quality standard based assessment procedure for permitting discharge

The 'combined approach' as a requirement of the EC Water Framework Directive pools an emission-based approach with an approach based on environmental quality standards (EQS) to improve European water quality. The implementation of the EQS-based approach poses problems of defining a reference water discharge, defining a distance, where the EQS are obligatory and thus have to be controlled after point discharge, considering incomplete mixing. To elaborate a simple assessment procedure including the aspects mentioned above is the point of discussion in this paper. On the basis of easily available data and references from several European countries, recommendations for an Austrian assessment procedure are presented.