TABLE OF CONTENTS The WFD defines new strategies against water pollution as a consequence of releases from point or diffuse sources. A new aspect of the EC water policy is the"combined approach", i.e. both limitations on pollutant releases at the source due to promulgation of emission limit values as well as the establishment of environmental quality standards. Releases of pollutants - especially from point sources - must meet both requirements. For most European member countries this new policy means a considerable deviation from current water quality management practice by which the releases of pollutants has been controlled by either one of these two control mechanisms, but usually not their combination.
Ragas et al. (1997) have reviewed the advantages and disadvantages of different control mechanisms in the permitting processes of releases into surface water. Emission limit values (ELV) present a direct and effective method for the limitation of pollutant loadings by restricting the concentration for the mass flux of specific pollutants. ELVs are preferred from an administrative perspective because they are easy to prescribe and to monitor (end-of-pipe sampling). From an ecological perspective, however, a quality control that is based on ELVs alone appears illogical and limited, since it does not consider directly the quality response of the water body itself and therefore does not hold the individual discharger responsible for the water body. To illustrate that point consider a large point source on a small water body or...
