This dataset contains actual (non-normalized) riverine flow as well as actual atmospheric and waterborne inputs of nitrogen and phosphorus. In addition the dataset includes the normalized total nutrient inputs (atmospheric + waterborne) of nitrogen and phosphorus into the Baltic Sea. The data are used in the HELCOM core indicator on Inputs of nutrients (nitrogen and phosphorus) to the sub-basins 1995-2020 (https://indicators.helcom.fi/indicator/inputs-of-nutrients/). The river input data is based on reported riverine monitoring data as reported in HELCOM PLC data collection. Data on waterborne inputs, water flow and retention are reported by Contracting Parties to the PLC-Water database. The data are verified and quality assured using the PLC water database (https://nest.su.se/helcom_plc/) verification tools and national expert quality assurance. Atmospheric input data for all Baltic Sea sub-basins are available for the period 1990-2020. Atmospheric transport and deposition of nitrogen compounds are used for modelling atmospheric deposition to the Baltic Sea based on official emission data reported by EMEP Contracting Parties and expert estimates. Atmospheric input and source allocation budgets of nitrogen (oxidized, reduced and total) to the Baltic Sea basins and catchments were computed using the latest version of EMEP MSC-W model. Input of nutrients (N=Nitrogen, P=Phospohus) units are tonnes per year per HELCOM PLC Subbasin. Area delineation of HELCOM PLC subbasins can be accessed from https://maps.helcom.fi/website/mapservice/?datasetID=1456f8a5-72a2-4327-8894-31287086ebb5 Subbasin acronyms stand for: BOB: Bothnian Bay BOS: Bothnian Sea (including ARC = Archipelago Sea) BAP: Baltic Proper GUF: Gulf of Finalnd GUR: Gulf og Riga DS: Danish Straits (= WEB + SOU) (= Western Baltic + Sound) KAT: Kattegat BAS: The Baltic Sea

Nutrient monitoring activities in the Leningrad and Kaliningrad regions have been implemented within BASE Project. BASE supports the implementation of the Baltic Sea Action Plan (BSAP) in Russia. The monitoring pilot project is focused on the assessment of the nutrient loads coming to the Baltic Sea from Russian part of the catchment. The main activities within the pilot project include nutrient sampling and flow measurements in the river Neva catchment (downstream outlet from Lake Ladoga) and in the water objects of Kaliningrad region (Pregolya and its tributaries, other rivers of Vistula and Curonian Lagoon etc.). More information about results can be found from the BASE Project final report from the HELCOM website.

Nutrient monitoring activities in the Leningrad and Kaliningrad regions have been implemented within BASE Project. BASE supports the implementation of the Baltic Sea Action Plan (BSAP) in Russia. The monitoring pilot project is focused on the assessment of the nutrient loads coming to the Baltic Sea from Russian part of the catchment. The main activities within the pilot project include nutrient sampling and flow measurements in the river Neva catchment (downstream outlet from Lake Ladoga) and in the water objects of Kaliningrad region (Pregolya and its tributaries, other rivers of Vistula and Curonian Lagoon etc.). More information about results can be found from the BASE Project final report from the HELCOM website.

Nutrient monitoring activities in the Leningrad and Kaliningrad regions have been implemented within BASE Project. BASE supports the implementation of the Baltic Sea Action Plan (BSAP) in Russia. The monitoring pilot project is focused on the assessment of the nutrient loads coming to the Baltic Sea from Russian part of the catchment. The main activities within the pilot project include nutrient sampling and flow measurements in the river Neva catchment (downstream outlet from Lake Ladoga) and in the water objects of Kaliningrad region (Pregolya and its tributaries, other rivers of Vistula and Curonian Lagoon etc.). More information about results can be found from the BASE Project final report from the HELCOM website.

The objective of the Balthazar project was to assess the potential sources of nutrient loading from all types of large animal farms in the Kaliningrad and Leningrad regions and to perform risk assessment of nutrient leaching from the livestock farms into Baltic Sea. Report on large scale agricultural waste management activities: http://www.helcom.fi/stc/files/Publications/OtherPublications/agricultural_full_english.pdf

Screening activities for component Hazardous wastes on the Leningrad and Kaliningrad Region territories have been fulfilled within the BALTHAZAR project. The main goal of the Project BALTHAZAR is assistance in protection of the Baltic Sea from pollution through reducing of loading caused by agricultural entities (AE) and hazardous wastes. The component Hazardous wastes is focused on inventory of large landfills and estimation of current regime in hazardous wastes management. The main task of screening was to study impact of large landfills on environment of the Leningrad Oblast and Kaliningrad Oblast and to reveal the landfills causing the main loading on the Baltic Sea with pollutants. Screening results report on Leningrad: http://www.helcom.fi/stc/files/Projects/BALTHAZAR/ScreeningReportForPublication-May2011.pdf Screening results report on Kaliningrad: http://www.helcom.fi/stc/files/Projects/BALTHAZAR/KaliningradScreeningResults-1.pdf

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.

Screening activities for component Hazardous wastes on the Leningrad and Kaliningrad Region territories have been fulfilled within the BALTHAZAR project. The main goal of the Project BALTHAZAR is assistance in protection of the Baltic Sea from pollution through reducing of loading caused by agricultural entities (AE) and hazardous wastes. The component Hazardous wastes is focused on inventory of large landfills and estimation of current regime in hazardous wastes management. The main task of screening was to study impact of large landfills on environment of the Leningrad Oblast and Kaliningrad Oblast and to reveal the landfills causing the main loading on the Baltic Sea with pollutants. Screening results report on Leningrad: http://www.helcom.fi/stc/files/Projects/BALTHAZAR/ScreeningReportForPublication-May2011.pdf Screening results report on Kaliningrad: http://www.helcom.fi/stc/files/Projects/BALTHAZAR/KaliningradScreeningResults-1.pdf