The NENUPHAR Deliverable D2.4, named Best Practices for the Implementation of Governance Models, provides an exhaustive analysis of governance structures and models to enhance the handling of nutrient pollution and the recycling of nutrients. The report, which was developed under T2.5 Elaboration of best practices for the implementation of governance structures and models from WP2 Governance Models to Support Dialogue and Cooperation, explores the concept of governance through the analysis of the different structures and models in the project demo-sites, analyse the knowledge on governance issues from a range of experts, and provides general recommendations for improving these structures. Our aim is to find new or complementary structures that could improve the nutrient management on river basins. The document begins by examining the governance concept, highlighting key structures such as hierarchical, market-based, and collaborative governance models. Then proceeds to evaluate governance success factors, including stakeholder participation, policy integration, and financial support, while also identifying barriers such as regulatory fragmentation and resistance to change. The document then moves on to discussing governance structures in place in the specific river basin demo cases: the Ebro, Danube and Lielupe to illustrate practical insights. The Ebro case highlights multi-level governance challenges between Aragon and Catalonia, the Danube case (one in Slovakia and one in Hungary) examines nutrient pollution from agriculture and dairy industries, and the Lielupe case explores governance in Latvia and Lithuania, emphasizing the role of local municipalities in nutrient management. The report concludes with a series of best practice recommendations for strengthening governance models building on Task 2.1 Assessment of current governance solutions and success cases, and from the results of the Community of Members (CoM) developed during Task 2.4 Establishment of the Community of Members. It also integrates the opinion of the Community of Interest (CoI) experts (Task 7.3 Community of Interest) for the establishment of multi-stakeholder governance platforms, enhanced regulatory enforcement, investment in precision agriculture, and the integration of circular economy principles. It is important to acknowledge that this analysis represents the initial phase of a longitudinal investigation. The discourse surrounding governance models will persist throughout the project's duration, facilitated by the CoM activities. The compilation and analysis of further recommendations will be conducted under WP6, with the results being reflected in Deliverable D6.4. This deliverable is tasked with the development of "guidelines for outlining effective instruments and governance models for the creation of regional CoM of actors and the establishment of innovative strategies for nutrient management." The adoption of innovative governance frameworks is expected to facilitate more effective nutrient management, enhance environmental sustainability, and align with EU directives.