On 23 October 2000, the EU Water Framework Directive was finally adopted. The Directive, which was published in the Official Journal (OJ L 327) on 22 December 2000 and entered into force the same day. The Water Framework Directive expands the scope of water protection o all waters and sets clear objectives that a “good status” must be achieved for all European waters by 2015 and that water use be sustainable throughout Europe. According the directive, the individual member states are obligated to describe ecological objectives or goals for the different waters. This project includes a theoretical study about how to define these ecological objectives. More specific this study will define ecological objectives for different biological quality elements (benthos, macro-algae, angiosperms and phytoplankton). Functional-ecological theories will be used to support the objectives or goals.