MUSTBE

Results

In urban areas, stormwater contains nutrients and hazardous substances, and in addition, stormwater management is crucial for managing urban flood risk. Interreg CB MUSTBE project aimed to maximize stormwater treatment efficacy and municipalities’ capacity to monitor stormwater quality by developing novel, multi-benefit and nature-based stormwater management systems combined with digital solutions. The protection of the Baltic Sea is a cross-border challenge and as such, seven pilot solutions were implemented in four Centra Baltic countries: Estonia, Latvia, Sweden and Finland.

The solutions were tailored to each area. They demonstrated that nature-based solutions can effectively improve stormwater management, reduce flooding risks, and enhance water quality, although performance varied by site and local conditions. Difficulties in monitoring effectiveness rose from the scheduling delays in construction and continued monitoring is therefore needed to assess long-term performance.

• Central Square in Pori, Finland – by adding more permeable surfaces and vegetation to a parking area, it managed to retain over 90% of the incoming stormwater and achieve all key qualitative targets.
• Wetland in Pori, Finland – targeting the effects of acid sulphate soils with a dam filtration system, the solution improved hydrology and acidity management, but the performance was hindered by external pollution sources.
• Broberg in Söderhamn, Sweden – combining retention ponds and urban ditches, achieved strong nitrogen, metal and pathogen removal but faced some seasonal deterioration issues.
• Porten in Söderhamn, Sweden – consisting of a meandering ditch and a retention pond, incoming water was largely retained and infiltrated, with no outlet discharge during the monitoring period.
• Viimsi, Estonia – a fountain using treated stormwater from the retention pond, long-term monitoring is needed as vegetation and treatment elements mature.
• Tallinn, Estonia – a wetland with a two-bond system and the largest initiative of its kind in Estonia, shows good potential, but is not fully operational in water treatment yet.
• Riga, Latvia – including sedimentation and filtration ponds, meandering stream paths, wet meadows and phytoremediation vegetation, performance is promising, with further monitoring required.