Agreement on these four principles between the six founder Member States (Belgium, France, Germany, Italy, Luxembourg and the Netherlands) led to completion of the Customs Union on 1 July 1968, one and a half years earlier than planned in the 1957 Treaty of Rome.
Dalībvalstīm līdz 2009.gada beigām jāapkopo dati par virszemes ūdens kvalitāti, tajā ietverot piesārņojuma kartes, ja iespējams, arī par prioritāri bīstamo vielu emisiju un noplūdes vietām.