Common reed and the little moving water in the Eteläinen kaupunginselkä (Southern city bay) area of Vaasa have suffered from declining water quality over the years as increasing nutrient loads and expanding reed beds reduce water circulation in the area. This has already impacted Vaasa’s swimming water quality with two EU-beaches (Ahvensaari and Hietasaari) classified as having poor swimming water quality, despite being located in the heart of the city for public use. Combined the affected area of common reed is approximately 3 square kilometres just in one area, with several other large areas in river deltas around the Ostrobothnia.
The growth of common reed has coincided with the reduction of coastal grazing and increased use of agricultural fertilizers, both of which have strongly contributed to the current situation. Fertilizer runoff is carried from fields into rivers, which transport nutrients into deltas.
