Article 4 of the Water Framework Directive (WFD) permits exemptions if the necessary measures for achieving the environmental objectives of the Directive will have disproportionate costs. In this project, a set of criteria and a step-by-step procedure were developed to assess the disportionality of costs in a practicable and quick way. The main focus in this context was on the affordability of measures - when is it possible to conclude that the costs of the measures exceed the accepted party's ability to pay?

2007: Verhältnismäßigkeit der Maßnahmenkosten im Sinne der EG-Wasserrahmenrichtlinie – komplementäre Kriterien zur Kosten-Nutzen-Analyse. Helmholtz-Zentrum für Umweltforschung – UFZ/Ecologic, Institut für Internationale und Europäische Umweltpolitik/ Universität Leipzig, Institut für Infrastruktur und Ressourcenmanagement, Stiftungsprofessur für Umwelttechnik/Umweltmanagement. Leipzig/Berlin.