Eutrophication caused by oversupply of the Baltic Sea by nutrients remains the major environmental pressure on the marine ecosystem. In order to mitigate eutrophication, HELCOM countries have agreed on a joint effort to reduce nutrient load on the marine ecosystem, reflected in the HELCOM Baltic Sea Action Plan as a nutrient input reduction scheme. Compilations of pollution load data, designed to follow up on the implementation of the scheme, have been an integral part of the HELCOM assessment system since 1987. This assessment of major sources and pathways of nitrogen and phosphorus into the marine environment is a vital part of the HELCOM Pollution Load Compilation (PLC) and one of the main products of the HELCOM Sixth Pollution Load Compilation project (PLC-6). The product includes an assessment of three major pathways of nutrients – riverine, airborne and via direct sources – and more detailed assessment of sources of riverine load.

The previous (PLC-5) assessment, published in 2013, was based on the data on nutrient inputs in 2006. Current assessment illustrates the contribution of various sources of nitrogen and phosphorus into total loads in 2014 (2012 for Germany and Poland). The assessment also illustrates changes in proportion of different pathways since 1995.