The Department must ensure that the guideline value adopted as a result of paragraph 1 and samples are analysed in accordance with the following provisions of this paragraph.

Subject to sub-paragraph (1), sampling shall be carried out at least at the minimum frequency specified in Table 1 to this Schedule.

Where sampling shows that the guideline value adopted as a result of paragraph 1 is not being met, the Department must establish whether this is the result of chance, a natural phenomenon or pollution, and must adopt appropriate measures to prevent deterioration.

Samples shall be analysed using the reference methods of analysis specified in Table 1 to this paragraph or methods which are at least as reliable as the reference methods.