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The environmental objectives of the Water Framework Directive (WFD) are defined in Article 4. The aim is long-term sustainable water management based on a high level of protection of the aquatic environment. The WFD classification scheme for water quality includes five status categories: "high", "good", "moderate", "poor" and "bad". The general objective of the WFD is to achieve "good status" for all surface waters by 2015. "Good status" means both "good ecological status" and "good chemical status". "High status" is defined as the biological, chemical and morphological conditions associated with no or very low human pressure. This is also called the "reference condition" as it is the best status achievable - the benchmark. These reference conditions are type-specific, so they are different for different types of rivers, lakes or coastal waters so as to take into account the broad diversity of ecological regions in Europe. For the coastal water bodies "reference conditions" for the quality components phytoplankton, macroalgae and angiosperms and benthic invertebrate fauna has to be defined. In combination with the biological quality components, supporting hydro-morphological and physico-chemical components have to be involved in the classification process. According to the WFD a hierarchical approach for defining reference conditions is suggested using the various methods in the following order: 1) an existing undisturbed site or a site with only very minor disturbance, 2) historical data and information, 3) models or 4) or expert judgement. Concerning the Oderhaff no undisturbed site or a site with only very minor disturbance can be found to define reference conditions of a "high status". Thus historical data and/or models have to be used to define these reference conditions. There are already some aproaches to define these reference conditions for the biological and physico-chemical quality components for the Oderhaff. In this article these approaches will be briefly introduced and discussed as they correspond to the guidelines of the WFD.