Aim of this Decree is the implementation of paragraphs 1 and 2 of article 4 to Ministerial Decree No. 16190/1335/1997, in compliance with the provisions of paragraphs 1 and 2 respectively of article 3 to Council Directive 91/676/EEC. It also aims at amending the above-mentioned Decree in such a way that the protection of waters can be effectively achieved: a) by identifying those water basins that are susceptible to nitrate pollution of agricultural origin and classify them as “vulnerable”, and b) by simplifying the procedures pursuant to article 5 of Decree No. 16190/1335/1997. According to the above and the conditions set forth in article 4, paragraph 3a of Decree No. 16190/1335/1997, this Decree establishes the Catalogue of vulnerable zones and identifies among them the following four areas: 1) Western and Eastern Thessaly; 2) Kopaida; 3) Argolikos; 4) Pineios river basin. The delimitation of these areas are pinpointed on maps attached to this Decree. The Catalogue shall be revised or supplemented as needed. In the vulnerable areas, action programmes shall be established and implemented in order to reduce water pollution from nitrogen compounds. In the above-mentioned areas, follow-up and monitoring programmes shall be applied and shall be repeated per four-year period while at the same time shall be assessed the eutrophication of waters. This Decree also amends articles 3, 4, 5, and 8 of Decree No. 16190/1335/1997.