A wetland in Parainen improves the area’s natural values and water quality

A new water protection wetland designed by Turku University of Applied Sciences has been completed in Sydänperä in Parainen. The wetland is designed to improve the water quality of Ålönlahti and the habitat of many plant and organism species.  The location of the wetland was chosen to be an old arable land owned by the city of Parainen on the shore of Sydänperälahti on the island of Ålö, which has been fallow for years.

The purpose of the wetland completed in Sydänperä in Parainen is to retain the solids carried by the ditch water and the nutrients bound to it. The ditch flowing into Sydänperänlahti collects its water from a 92-hectare catchment area dominated by agriculture and forestry. The size of the wetland is not enough to treat all the ditch water at peak discharges, which means that only part of the water is directed to the wetland to be cleaned.

Turku University of Applied Sciences (Turku UAS) has carried out a vegetation survey in the area in the summer of 2024 as a student project and preliminary measurements as a basis for the wetland plan. In autumn 2024, an implementation plan was drawn up for the wetland and a contractor for the wetland was put out to tender.  The excavation work began in December, after which the implementation progressed quickly and the excavation work of the wetland was completed before Christmas. In the spring of 2025, an erosion protection mat was installed on the edges of the wetland in a voluntary effort organised by Turku UAS and the Ålönlahti Foundation, and meadow seed mixture was sown to further strengthen the biodiversity of the area.

The wetland was built in the Ålönlahti pilot project coordinated by Turku UAS. The project is part of a wider work on the Archipelago Sea, which aims to improve the condition of the Archipelago Sea and its catchment area. In addition to Turku UAS, the project involves the Ålönlahti Foundation, the Water Protection Association of Southwest Finland and the City of Parainen.

The Sydänperä wetland is an example of how nature-based solutions can be used to promote water protection and biodiversity. The wetland serves as both a water purifier and a valuable habitat for many species.

− Through the project, we want to encourage other actors to take similar measures to promote the protection of the Archipelago Sea and its catchment area, says Antti Kaseva, Project Manager at Turku UAS.

In addition, there is a dry meadow area next to the wetland area, which is a valuable traditional biotope. The Ruokohelmi II project of Turku UAS, which has already ended, promoted the preservation of the traditional biotope by building a fence in the area for future horse grazing.

Opening event open to all

An event open to the public will be held at the wetland on Thursday 8 May from 17:00 to 18:00. The opening event will be held at Sydmonpolku, Parainen.

The event is open to all those interested in wetlands, the status of Ålönlahti or other water protection issues. The event will provide an opportunity to hear and discuss the wetland and other environmental measures in the area and what everyone can do to promote water protection and biodiversity in Ålönlahti.

The event is organised by Turku UAS, Ålönlahti Foundation and the City of Parainen.

Further information

Aija Mäkinen, Turku UAS, tel. 050 4757 969, aija.makinen@turkuamk.fi

Kurt Lundqvist, Ålönlahti Foundation, tel. 050 4121 468, kurt@bioproton.com