Occurrence and removal of milfoil in Naantali

Testing the mapping, removal, and utilization of Eurasian watermilfoil

Duration of the project

1.6 – 30.11.2025

Source of funding

Leader Varsin hyvä

Total funding

60 452 €

The raven fly is invading water bodies and water users are calling for measures to reduce its impact. So far, there is relatively little published information on the effects of aquatic plant removal and the results of harvesting. The project will investigate the presence of Eurasian watermilfoil in Naantali and test its removal in a pilot area.

The project will investigate the suitability of drone imaging for mapping Eurasian watermilfoil, test the removal and utilization of Eurasian watermilfoil, and assess the effects of harvesting in the pilot area. The aim is to utilize the harvested biomass as nutrients for fields. The goal is to obtain an overall picture of the occurrence of Eurasian watermilfoil in Naantali, which is why its occurrence is also mapped by collecting citizen observations from the municipal area.

Testing of aquatic plant removal will be carried out in 2026. The vegetation will be mowed mechanically and the plant biomass will be collected as accurately as possible. Harvesting Eurasian watermilfoil removes nutrients from the sea, and the utilization experiment on nearby fields aims to achieve local nutrient cycling.

The project is coordinated by Turku University of Applied Sciences. The project partners are the City of Naantali and the Nuikonlahti Water Protection Association. The project has received European Agricultural Fund for Rural Development from the Leader group Varsin hyvä.

Photo by Joonas Hoikkala (Metsähallitus)