Council Directive 91/676/EEC of 12 December 1991 Concerning the Protection of Waters Against Pollution Caused by Nitrates from Agricultural Sources. Available online: http://eur-lex.europa.eu/ LexUriServ/LexUriServ.do?uri=CELEX:31991L0676:EN:HTML (accessed on 12 August 2014). 35. Billen, ...