Throughout the European Union (EU), agricultural practices contribute significantly to the pollution of water resources by nitrates, phosphorus and pesticides. This article sheds light on the degree of horizontal legal coherence between the main EU legal and policy instruments applicable to the protection of water resources from agricultural pollution. After identifying key coherence challenges at the EU level, the article thoroughly assesses the regulatory and governance approach in Norway. The key question is how certain EU-level coherence challenges could be mitigated at a national level through mechanisms aimed at facilitating cross-sectoral coordination and policy coherence. Three types of mechanisms have been selected for this purpose: (i) legal mechanisms, including cross-referencing and joint institutional responsibility for implementation; (ii) the establishment of platforms for cross-sectoral policy coordination or actor participation; and (iii) the establishment of monitoring and reporting processes that ensure access to information and data sharing.