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 2012-2014. 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 2014 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. The last 3-year assessment (2012-2014) reveals the average normalized input of nitrogen was reduced by 13% and phosphorus by 19% since the reference period (1997-2003). The maximum allowable input (MAI) of nitrogen in this period was fulfilled in the Kattegat, Danish Straits and Bothnian Sea (Tables). Nitrogen inputs into Bothnian Bay and the Gulf of Riga are close to MAI but cannot be considered as fulfilled due to statistical uncertainty. MAI for phosphorus input is fulfilled in the Kattegat only. The inputs to the Danish Straits, Bothnian Sea and Bothnian Bay cannot be considered as fulfilled due to statistical uncertainty. Accordingh to the long term trend analysis, since the mid-1990s, total normalized nitrogen and phosphorus inputs to the Baltic Sea in 2014 were reduced by 19% and 24%, respectively.

Table. The average normalized annual inputs of nitrogen and phosphorus during 2012-2014. The table also includs statistical uncertainty, inputs in 2012-2014 including statistical uncertainty and the remaining reduction needed to reach 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.
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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 section of the HELCOM core indicators web page and specifically the
Core pressure indicator on nutrient inputs (MAI follow up).