HELCOM regularly produces a Pollution Load Compilation (PLC) which assesses the data collected by the Contracting Parties on total air and waterborne inputs of nutrients and some hazardous substances to the Baltic Sea. PLC are an important part of HELCOM´s assessment system on the status of the Baltic marine environment since 1987. HELCOM Pollution Load Compilation database (HELCOM PLC database) contains waterborne discharge data collected and reported by HELCOM Contracting Parties for annual and periodic assessments of inputs of nutrients and selected hazardous substances in to the Baltic Sea. Description of the data collected in the PLC database is presented in the HELCOM Guidelines for the annual and periodical compilation and reporting of waterborne pollution inputs to the Baltic Sea: http://www.helcom.fi/Lists/Publications/PLC-Water-Guidelines-2019.pdf The database is hosted by Baltic Nest Institute, Stockholm University Baltic Sea Centre.

The data set includes the water flow and the actual, non-normalized, nutrient inputs (total nitrogen and phosphorous) of monitored river catchments and unmonitored areas as well as the nutrient inputs from point sources (municipal, industrial and aquaculture) that are directly discharging into the sea. The data covers the whole Baltic Sea drainage area and the years 1995-2021. Together the riverine and point source inputs provide the total land-based load of nutrients into the Baltic Sea. The data consists of several excel spreadsheets providing background info and actual load values. The spatial delineation of these catchments can be accessed through the metadata record for PLC Assessment data river catchments (https://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/d7b5404a-b3e1-4fe6-be35-a12055736783). The tabular and the spatial data includes the catchments that have a full time series of data for 1995-2021, and the nutrient load of rivers with incomplete time series are added to the adjacent unmonitored areas. The data is used in the HELCOM Baltic Sea Environmental Fact Sheet (BSEFS) on Waterborne nitrogen and phosphorus inputs and water flow to the Baltic Sea 1995-2021 that is published annually (https://helcom.fi/baltic-sea-trends/environment-fact-sheets/eutrophication/). The assessment data set is based on the reporting by HELCOM Contracting Parties within the Pollution Load Compilation framework (PLC). The assessment dataset is produced by the Baltic Nest Institute (BNI), Stockholm University together with the Danish Centre for Environment and Energy (DCE), Aarhus University from the original reported data. For a more detailed description of the spreadsheets and included data, please scroll down to lineage.

The dataset reflects the spatial delineation of river catchments in the Baltic Sea drainage area. The data is based on the reporting by Contracting Parties within in the HELCOM Pollution Load Compilation (PLC) framework. The catchments consist of monitored river catchments and unmonitored coastal areas. The delineation of the catchments can be connected to the flow and nitrogen and phosphorous load information available in the Baltic Sea Environmental Fact Sheet (BSEFS) assessment data set (https://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/441f878f-67e7-4aa8-927e-8f5e073dc893). The river catchments consist of whole rivers, meaning that although a river would run through several countries or would be a border river between two countries, the catchment is not split into separate sub-catchments. The unmonitored areas are aggregated based on PLC subbasins and country areas, thus forming areas such as the unmonitored area of Finnish Gulf of Finland, Polish Baltic Proper or Danish Kattegat. Attribute information: SourceCode: Unique code for river catchment Name: Name of river catchment SubBasin: The PLC subbasin where the river meets the sea. Country: The Country on which territory the river mouth is located, for border rivers both are mentioned. Monitoring: The monitoring status of the river (M=monitored and U=unmonitored). Marked as monitored only if it’s been monitored for the whole time series. Transbound: Listing all countries that have the rivers drainage area on its territory. Area_km2: The total area of the catchment in square kilometers.