Baltic Marine Environment
Protection Commission

Progress towards Maximum Allowable Inputs

Maximum Allowable Inputs (MAI) of nutrients are a part of the HELCOM nutrient reduction scheme, indicating the maximal level of total (water- and air born) input of nitrogen and phosphorus to the Baltic Sea sub-basins (map layer for nitrogen and phosphorus at the HELCOM map service) that is allowed to fulfil the targets for the sea unaffected by eutrophication. The targets were first included into the Baltic Sea Action Plan in 2007 and then updated in the Copenhagen Ministerial Declaration in 2013. Input of nutrients is one of HELCOM core pressure indicators.

The current assessment of progress towards MAI of nitrogen and phosphorus is based on data on normalized average total input to the sub-basins of the Baltic Sea during 2012-2018. The fulfilment of MAI is identified by comparing the total input to a particular sub-basin with the Maximum Allowable Input for that sub-basin. The progress achieved by 2018 is given in percentages of MAI where values below 100% indicate fulfilling the requirements of the HELCOM nutrient reduction scheme.

A significant reduction of nutrients input has been achieved for the whole Baltic Sea. This assessment shows that the normalized input of nitrogen was reduced by 12% and phosphorus by 26% between the reference period (1997-2003) and 2018 (Results figure 1). In 2017 the corresponding reductions were 14% for total inputs of nitrogen and 24% for total phosphorus. The maximum allowable input (MAI) of nitrogen in this period was fulfilled in the Bothnian Bay, Bothnian Sea, Danish Straits and Kattegat (Key message figures 1 and Results tables 1a and 1b). MAI for phosphorus input was also fulfilled in the Bothnian Bay, Bothnian Sea, Danish Straits and Kattegat. The inputs to the Gulf of Finland were below MAI but cannot be considered as fulfilled due to statistical uncertainty.

Results table 1. 

The trend-based estimate for normalized annual inputs of (a) nitrogen and (b) phosphorus during 2018. 

The table also contains data on statistical uncertainty, the remaining reduction needed to reach MAI and inputs in 2018 including statistical uncertainty in percentages of MAI. Classification of achieving MAI is given in colours: green=MAI fulfilled, yellow= fulfilment is not determined due to statistical uncertainty, and red=MAI not fulfilled. (Units in columns 2-5: tonnes per year). NOTE: For consistency with MAI no rounding (to tenth, hundreds or thousands) has been performed in the indicator.


Table 1a


Table 1b

*) As adopted by the 2013 HELCOM Copenhagen Ministerial Meeting (HELCOM 2013a)
**) Exceedance of MAI is caused by statistical data uncertainty.

Detailed description

The detailed description of the indicator including data on air- and water born input as well as long term trends of inputs since the mid-1990s is given in the relevant sections of the HELCOM core pressure indicator on nutrient inputs report.