Water quality : definition Water quality objectives are defined in EEC Directives The Surface Water Directive (1975) The Bathing Water Directive (1976) + update proposed in 1994 The Dangerous Substances Directive (1976) + daughter directives The Fish Water Directive (1978) The Shellfish Water Directive (1979) [ The Drinking Water Directive (1980) ] The Urban Waste Water Treatment Directive (1991) The Nitrates Directive (1991) from agricultural sources The Proposed Ecological Quality of Water Directive (com 1993) Emission limits in effluents are defined by member states to achieve the quality objectives fixed in the directives. Absolute limits: Relative limits: Recent EEC Directives are a compromise of these two kind of limits Directive on urban sewer Directives concerning the protection of surface waters from dangerous substances (ex: HCH). easy to define and control but may be uselessly restrictive and therefore uneconomical provide a greater level of protection and saving of economic resources but are very complex to establish and have to be regularly updated to consider new discharges (ex: Spain).

Effluent discharge limits in Spain (in Galassi and Marchetti, 1991) Directive 84/491 on hexachlorocyclohexane (HCH) absolute limit for effluents of production plants : 2 mg/l maximum load per quantity of HCH produced : 2g/t quality objective :< 100 ng/l for internal waters < 20 ng/l for estuarine and sea waters For sediment, crustaceans, fish and molluscs, the adopted criterion is that the concentrations existing before the discharge must not be exceeded.

Chemical indices Based on physico-chemical measurements: Dissolved oxygen DBO 5 DCO NH 4 +, NO 3 -, NO 2 -, PO Exemple of quality physico-chemical indice (Institut d’Hygiène et d’Epidémiologie, Belgium) Very bad Very good Class Dissolved O 2 %

Data requirements for risk assessment of chemicals (depending on the production or import volume) Not required