# Council Directive of 12 December 1991 concerning the protection of waters against pollution caused by nitrates from agricultural sources (91/676/EEC), Article 6

Extent: E+W+S+N.I.

1. For the purpose of designating and revising the designation of vulnerable zones, Member States shall:
(a) within two years of notification of the Directive, monitor the nitrate concentration in freshwaters over a period of one year:
(i) at surface water sampling stations, laid down in Article 5 (4) of Directive 75/440/EEC and/or at other sampling stations which are representative of surface waters of Member States, at least monthly and more frequently during flood periods;
(ii) at sampling stations which are representative of the groundwater aquifers of Member States, at regular intervals and taking into account the provisions of Directive 80/778/EEC;
(b) repeat the monitoring programme outlined in (a) at least every four years, except for those sampling stations where the nitrate concentration in all previous samples has been below 25 mg/l and no new factor likely to increase the nitrage content has appeared, in which case the monitoring programme need be repeated only every eight years;
(c) review the eutrophic state of their fresh surface waters, estuarial and coastal waters every four years.
2. The reference methods of measurement set out in Annex IV shall be used.

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Source: https://www.legislation.gov.uk/eudr/1991/676/article/6 (the official version)
Page: https://openlegislation.uk/eu-directive-1991-676/article-6
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.