The HELCOM Nutrient Reduction Scheme is a regional approach to sharing the burden of nutrient reductions to achieve the goal of a Baltic Sea unaffected by eutrophication agreed by the Baltic Sea countries. The Scheme has been introduced and agreed first in 2007, in the HELCOM Baltic Sea Action Plan. At that time, the countries agreed on provisional nutrient reduction targets and decided that the figures will be revised using a harmonised approach and most updated data as well enhanced modelling. The revision process started in 2008 and was completed in 2013.There are two main components of the nutrient reduction scheme:
Maximum Allowable Inputs (MAI) of nutrients, indicating the maximal level of inputs of water- and airborne nitrogen and phosphorus to Baltic Sea sub-basins that can be allowed to fulfill the targets for non-eutrophied sea;
Country-Allocated Reduction Targets (CART), indicating how much nutrient inputs the HELCOM countries need to reduce comparing to a reference period (1997-2003).
HELCOM estimated in 2007 that for good environmental status to be achieved, the maximum allowable annual nutrient pollution inputs into the Baltic Sea would be 21,000 tonnes of phosphorus and about 600,000 tonnes of nitrogen. Annual reductions of some 15,000 tonnes of phosphorus and 135,000 tonnes of nitrogen would be required to reach to achieve the plan's crucial "clear water" objective.
The HELCOM Ministerial Meeting 2013 in Copenhagen adopted the revised HELCOM nutrient reduction scheme.