Article 7
1.The competent authorities in the Member States shall carry out sampling operations, the minimum frequency of which is laid down in Annex I.
2.Where the competent authority records that the quality of designated waters is appreciably higher than that which would result from the application of the values set in accordance with Article 3 and the comments contained in columns G and I of Annex I, the frequency of the sampling may be reduced. Where there is no pollution and no risk of deterioration in the quality of the waters, the competent authority concerned may decide that no sampling is necessary.
3.If sampling shows that a value set in accordance with Article 3 or a comment contained in columns G or I of Annex I is not respected, the competent authority shall establish whether this is the result of chance, a natural phenomenon or pollution and shall adopt appropriate measures.
4.The exact sampling point, the distance from this point to the nearest point where pollutants are discharged and the depth at which the samples are to be taken shall be fixed by the competent authority of each Member State on the basis of local environmental conditions in particular.
5.The reference methods of analysis to be used for calculating the value of the parameters concerned are set out in Annex I. Laboratories which employ other methods shall ensure that the results obtained are equivalent or comparable to those specified in Annex I.