The term 'discharge' in Article 1(2)(d) of Directive 76/464 on pollution caused by certain dangerous substances discharged into the aquatic environment of the Community includes the placing by a person in surface water of wooden posts treated with creosote. Directive 76/464 allows Member States to make the authorisation of a discharge subject to the investigation or choice of alternative solutions which have less impact on the environment, even though this is not provided for in that directive and the criteria for such authorisation may make the actual granting impossible or altogether impossible.