Eutrophication is one of the major threats to the marine environment in the Baltic Sea. The human pressure on the sea by nutrient input from agriculture, industry, public sewage facility and small sewage treatment plants causes excessive algal blooms leading to oxygen depleted seabed and an ecosystem out of balance. The objective of this study is to investigate how local legitimacy and fairness is addressed in the multilevel and complex issue of reducing Baltic Sea eutrophication. The main results show that there is a great challenge and uncertainty in dealing with the problem of eutrophication. Furthermore, there is an unfair distribution of costs and responsibilities related to wastewater treatment in the municipal planning documents and nearly total exclusion of the individual property owners from participating in the decision-making processes related to the expansion plans for public sewage facility. This in turn risks the legitimacy and the democratic aspects of the plans. Previous studies related to public and simple sewage plants have investigated different issues related to the legislation and practical planning as possible reasons for a sluggish progress in the measures to reduce nutrient discharges to the sea. However, the fairness aspects and the participatory processes of the plans have not been studied. The implications of this study are to invite to a more inclusive and fair planning process with the use of alternative solutions to the compulsory expansion of public sewage facility. Modifications in the legislation to include economic instruments creating incentives for the property owners can be a way of increasing participation and thus the legitimacy of the system.