2021 11 26

The žerkščiai dam has been removed

There are more than a thousand different dams in Lithuania, almost a third of which are possibly threatened by their unsatisfactory condition. Dams harm migratory fish and damage the entire ecosystem. Recently, the removing of dams in protected areas has begun.

Dams not only prevent fish from migrating to spawning grounds, but also disrupt the natural flow of the river, habitats and change species communities.

The Bražuolė Dam in the Neris Regional Park is the first dam removed in the country for nature protection purposes. It has been removed to restore the free flow of a naturally important river. The removing of the Bražuolė stream dam, which is in an emergency, should improve the ecological situation and open spawning grounds for migratory fish, especially salmon. Bražuolė flows in an exceptional place, which due to its unique habitat is included in the EU network of protected areas "Natura 2000".

The Salantas River was also liberated in the summer: the 90 m long section of the river below the dam was cleared, the 46 km migration route for protected fish species was cleared, and an artificial spawning ground for sea trout, small and river lampreys was established. The Salantas River and its valley are one of the most important natural values ​​of the Salantai Regional Park and fall into the areas important for the protection of Natura 2000 ecological network habitats and birds.

Remains of the Žerkščiai dam have been removed in the Venta Regional Park, and the ecological condition of the Venta River in the section near the village of Žerkščiai has been improved. Due to the stone dam, the hydrological regime of the river changed, the water level rose and sediments accumulated. It is unfavorable for breeding and survival of protected species - thick shelled river mussel, river lamprey. Thick shelled river mussels live in clean, cold, flowing waters with a sandy and fine gravel bottom. Dams hinder the migration of fish, which are important for the reproduction and migration of thick shelled river mussel.

After restoring the damaged hydrological regime of the Venta River at the Žerkščiai mill, favorable habitat conditions have emerged for the following protected species: amur bitterling, thick shelled river mussel, river lamprey, spined loach.

In the Dubysa River in the Dubysa Regional Park, the removal of reinforced concrete bridge and dam remains has already begun to facilitate the migration of salmonids. These dams affected the deceleration of the Dubysa River, contributed to the rise in water temperature, bottom siltation, and eutrophication. In this way, they not only hinder the migration of fish, but also lead to the deterioration of salmonid habitats. It is planned to permanently remove construction waste from the Dubysa riverbed, which has become an obstacle to fish migration.

Almost 5,000 dams have already been removed in Europe to open up fish migration routes. The European Commission's recently announced new Biodiversity Strategy provides for the opening of 25,000 kilometers of free river sections through the removing of dams.