Dams negatively impact water quality

Dams created in the watercourses cause numerous nature conservation problems. For instance, they change the flow conditions, create stagnant water sections, change the composition of the sediment, influence the water quality and hinder migration of aquatic organisms along the water course. Our aim in the project is to better understand these effects and make recommendations to mitigate them.

Our investigations are carried out at 5 sites, in River Rába at dams of Ikervár, Nick and Magyarlak, in the River Pinka at the dam of Felsőcsatár, and in the River Répce at the dam of the Gyóró water mill. At each of these sites aquatic plants, aquatic macroscopic invertebrates, fish fauna, and water chemistry is studied.

The results of the study of aquatic macroscopic invertebrates and fish fauna show that the species composition changes upstream of the dam at each watercourse. The ecological quality (water quality) derived from the composition of the fish fauna above the dams is significantly worse than downstream of it. For example, at Magyarlak dam, the river section under the dam is in a 'good' ecological state, while the section above it has been classified as 'poor'.