In the project Multidom we try to assess the role of the dissolved organic matter (DOM below) in causing the pollution of the Baltic Sea from an interdisciplinary perspective. Our socio-economic objective is to create better conditions to improve the possibilities to reduce the DOM loading and and thus to improve the state of the Baltic. There are three sub-projects in Multidom: 1) DOM loading in the Baltic Sea and its social and economic impacts, 2) the analysis of the river DOM loading of DOM and risk and decision-making analysis based on probability calculations, 3) environmental history and policy of the Baltic Sea area.