Background Watersheds in urban environments are largely invisible and altered from their natural state. Widespread impervious surfaces, such as concrete and asphalt, and underground stormwater sewer networks have adversely altered watershed boundaries and lead to the rapid flow of untreated stormwater and snowmelt water into receiving bodies of water. Because of these artificial constructions, the ecosystem services provided by watersheds, such as water cleaning and regulation, are lost, with consequent harmful impacts on receiving waters. Innovative landscape structures and designs are needed to improve urban watersheds, and it is important to go beyond current standards and to develop prototypes for accurate and comparable monitoring. Wetlands, including peatlands, are known to have an important environmental role in cleaning water, as well as acting as carbon sinks, particularly in regions with colder climates because of their high primary production and slow degradation. The Baltic Sea is one body of water that has been suffering from changes to urban watersheds. The beneficiary participates actively in the Baltic Sea Challenge, a voluntary initiative to protect the Baltic Sea from all stakeholder activities. Objectives The Urban Oases project aims to study how alternative constructions in urban watersheds can improve the functioning of natural systems and ecosystem services, thereby helping to reduce run-off of polluting substances to receiving waters. It hopes to contribute to reducing contamination, algal blooms and eutrophication in receiving rivers and lakes, and ultimately to improve the water quality of the Baltic Sea. The project will study pilots in order to assess the potential for innovative stormwater wetland types and snow management swale structures as pervious waterways in densely constructed urban environments. The project actions will include the designs of all the prototypes and the monitoring stations. The beneficiary will assess the value of functional landscape elements in providing environmentally beneficial ecosystem services, covering impacts on: water quantity (flood control); water quality; greenhouse gases (sink or source); biodiversity. Expected results Outputs: Improved know-how on developing urban water ecosystem services through functional landscapes; Information about the costs of developing ecosystem services; Guidelines for two scale stormwater wetland types, as well as for structural stormwater and snow management swales for built-up urban areas, including refined soil mixtures, dimensioning and maintenance guidelines. Outcomes: Specific quality improvements in the management of water runoff in urban areas and the impact on ecosystems and receiving waters (the Baltic Sea); Improved biological diversity; Improved recreational value of water bodies; Increased collaboration on the implementation of functional and innovative urban landscape elements within the Baltic Sea region; Results and learning applicable to all urban areas within the EU.