The progress assessment is based on the evaluation of nutrient net input reduction towards to the net input ceilings.
The net input is an estimate of the amount of nutrients ending up in the Baltic Sea sub-basins coming from a particular country. The calculations integrate waterborne (direct coastal point sources and discharges from rivers), airborne (atmospheric deposition from a particular country or a group of countries) and transboundary (input via rivers through another country).
The net input ceiling is the maximum allowable amount of nutrients from a country to a sub-basin, assuring the good environmental status of the Sea in terms of eutrophication. The sum of input ceilings set for all countries to a specific sub-basin is equal to the Maximum Allowable Input for that sub-basin.
The fulfilling of the nutrient input ceilings was assessed using statistically estimated net nitrogen and phosphorus inputs from each country to the sub-basins in 2012, taking into account an estimated uncertainty on these inputs. The 2012 net inputs are compared with the corresponding nutrient input ceilings to assess the progress towards the targets. Statistical estimation uses a time series of normalized net inputs of nitrogen and phosphorus for the period 1995–2012.
The section Key message describes the still needed reductions to reach the HELCOM nutrient reduction targets set for a clean Baltic Sea. A description of the methodology used for the assessment can be found in section Follow up concept. A detailed description of the assessment results is given in a dedicated sub-section of the section Results, including tables with the net input ceilings and achieved reduction as well as the reductions since the reference period and in long-term retrospective.
All calculations complemented with the tables containing the data used in the assessment are given in thesection In-depth information. The section also integrates reference data, data on uncertainties obtained by the statistical procedures, data on inputs since 1995 and a description of how to account extra reductions into one sub-basin for the assessment of the reduction into the neighbouring sub-basins.