This paper uses the Organization for Economic Co-operation and Development (OECD) water governance principles to assess the governance of the implementation of the Baltic Sea Action Plan (BSAP), with a focus on the eutrophication segment. Whilst governance assessments can be used as auditing functions, this study was done with the goal of stimulating reflection, in order to investigate whether the governance systems have made any improvements. This is especially needed, since the BSAP is to be renewed in 2021, so that any assessment of it at this moment is timely. This review has focused on the 12 principles of water governance and the three complementary drivers into which the principles are grouped: Effectiveness, efficiency and trust, and engagement. This paper focuses on national implementation actions. It uses qualitative thematic analysis to analyze the content of the national implementation plans for Baltic Sea Coastal countries. It identifies gaps in water governance and makes recommendations for enhancing effectiveness, efficiency and trust, and engagement in the governance of the Baltic Sea, including improved stakeholder participation, the establishment of a permanent lead agency for the implementation of BSAP, increased funding for implementation actions, and a better governance of trade-offs.There is clearly a gap in the decision making and implementation of actions to achieve national nutrient reduction measures. It is this governance gap that spurs this study, which aims to assess the BSAP through the lens of the Organization for Economic Co-operation and Development (OECD) water governance principles. It explores the extent to which the HELCOM Baltic Sea Action Plan provides conditions for an effective application of the 12 principles of water governance, unveiled by the OECD in 2015. It focuses on the country level implementation of the BSAP, using the National implementation reports (NIP). Using this framework, it identifies factors that enable or constrain the implementation of the BSAP, and makes recommendations for improvement. This study is timely, as the findings can inform the process for the renewal of BSAP in 2021.