Dagvattnets föroreningar som potentiellt hot för en god ekologisk och kemisk status i ytvattnet : En kartläggning av Vallentuna tätorts dagvattenhantering utifrån dess tillsynsbehov

Sammanfattning: The EU's Water Framework Directive aims to a long-term and sustainable use of our water resources and wants to ensure good water quality in Europe's water bodies. Discharge of polluted stormwater into receiving waters can be a threat to their ecological and chemical status. Municipalities are responsible for supervision of the environmental quality standards (EQS) and therefore need to gain knowledge of current stormwater management, the expected level of pollution emissions and possible appropriate purification steps to ensure that the goal of good water quality is achieved. This master thesis aims to provide this knowledge in the example case of Vallentunas urban area and wants to prepare future oversight so that it can be assessed how much the discharge of polluted stormwater into the local receiving water is a threat to its status. With the help of maps, aerial photographs, site observations and individual discussions those areas are mapped where appearance of moderate to highly polluted stormwater could be suspected. The degree of pollution at the discharge points is determined based on land use upstream and uses standard values according to the administrators assistance "Tillsyn av dagvatten" (MSL 2014). The study identifies 100 areas in need of supervision regarding their stormwater management. The information is digitized and made available to all affected departments in the municipality via the internal GIS. Through literature review this thesis highlights even the legal provisions for the supervision and its importance to the environmental quality standards and also consider the importance of the expected climate change for the stormwater pollution. The work emphasizes the importance of increased information flow and communication between the different actors that are significant for surface water management and environmental quality standards for water. For being able to look at the examination area from an international perspective the essay does a simpler comparison of the municipal supervision of stormwater management between Sweden and the state of Schleswig Holstein in Germany.