Pursuant to Directive 76/464/EC, are hereby set limit values for emission standards for mercury in discharges from industrial plants, quality objectives for mercury in the aquatic environment, the time limits for compliance with the conditions of the authorizations granted by the competent authorities of Member States in the case of existing discharges, the reference methods of measurement enabling the mercury content in discharges and in the aquatic environment to be determined, and establishes a monitoring procedure, requiring Member States to cooperate with one another in the case of discharges affecting the waters of more than one Member State. The limit values, the time limits by which they must be complied with and the monitoring procedure for discharges are laid down in Annex I. The quality objective are set under Annex II. The reference method of analysis for determining the presence of mercury are given in Annex III. Other methods may be used if the limits of detection, precision and accuracy of such methods are at least as good as those laid down in Annex III. The Member States concerned shall be responsible for monitoring the aquatic environment affected by industrial discharges. In the case of discharges affecting the waters of several Member States, the Member States concerned shall cooperate with a view to harmonizing monitoring procedures. This Directive applies to the waters referred to in Article 1 of Directive 76/464/EEC with the exception of groundwater. (7 articles and 4 Annexes)