Unlike other indicators of this monitoring system, this indicator is mapped for the Baltic Sea, not at regional level for BSR regions. The indicator is generated by using the HELCOM Eutrophication Assessment Tool (HEAT), where a total of 189 measurement stations are classified regarding the level of their vulnerability against eutrophication. In previous years, the assessment ranges from moderate, poor and bad status (=affected) towards good and high status (=not affected); the latest classification, however, only distinguishes between good environmental status and below good status (=moderate or poor environmental status).
So far, the index has been produced three times, with each of the releases covering a period of several years, of which an average value has been produced. The 2009 release included data for years 2001-2006. The 2010 release included data for 2003-2007. The most current release derives from 2014 and covers the years 2007-2011. It should be noted that the latest 2014 release, as mentioned above, classification, only distinguishes between good environmental status and below good status. The 2014 release has thus been based on an, in parts, different methodology, simplifying the end result into only two different classes.
Eutrophication is an important indicator for the quality of the Baltic Sea and an indicator for how successful measures are to prevent the leakage of nutrients from agriculture and sewerage plants around the sea.
During the period 2003-2007 (average values, 2010 release), most of the Central parts of the Baltic Sea, Gulf of Finland and Gulf of Riga were in bad conditions. Medium conditions prevailed in the Bornholm basin and westwards and in the Bothnia Sea. Only the Bay of Bothnia was in good condition. Averaging the integrated classification over a time span from 2007 to 2011 (2014 release) reveals that almost the entire Baltic Sea is in moderate or poor environmental status in terms of eutrophication. Only parts close to the shorelines of the Bay of Bothnia in the Northernmost part of the Baltic Sea and a bay close to the German island of Fehmarn is in good condition.