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The major difficulties in preparing a new Directive concerning the ecological quality of surface waters are the definition of the ecosystem categories, the respective acceptable ecological standard for each of these categories and the classification procedures. This paper examines the various approaches (physico-chemical and biological) to the assessment of lake water quality, reviews some classification schemes currently in use and illustrates a proposal for the possible lake classification system to be used throughout the Community, based on generally accepted physico-chemical and biological features such as transparency, dissolved oxygen, chlorophyll and phosphorus concentrations, algae and macrophytes, macroinvertebrates and fish. Since the ultimate aim of this Directive should be to reach a high ecological quality in all surface waters, in the proposed classification scheme a matrix giving clear limitations of classes has been considered, taking into account also the morphoedaphic index. This allows the description of lentic systems in complying (two classes: excellent, good) and uncomplying waters (three classes: fair, poor, bad) and follows closely the evolution of the ecological quality of the Community waters, establishing basic (ecological) and minimum (managerial) objectives for lakes.

Additional information

Authors: PREMAZZI G, JRC Ispra (IT);CHIAUDANI G, University of Milan, Department of Biology (IT)
Bibliographic Reference: Paper presented: International Conference on River Water Quality - Ecological Assessment and Control, Bruxelles (BE), Dec. 16-18, 1991
Availability: Available from (1) as Paper EN 36565 ORA
Record Number: 199210193 / Last updated on: 1994-12-02
Original language: en
Available languages: en
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