There are classifications of rivers for biological, chemical and morphological parameters. The oldest assessment is the saprobic system „Saprobiensystem“. It uses the population of macrozoobenthos (invertebrates dwelling on the riverbed) to describe the oxygen content of watercourses. After 1980 classifications for chemical and morphological parameters were used too.
Now the status of waters is integratively assessed using a range of assessment criteria such as the biological and chemical ones, water volume and hydromorphology (EC Water Framework Directive). Chemical status is determined from the defined EU-wide environmental quality standards .There are two classes of chemical status. If the environmental quality standards are complied with, the status is "good", otherwise it is "not good".