Santekle Weir Removal, Lithuania

Introduction

The Salantas River is the right tributary of the Minija River that flows for roughly 43 km. It is situated in the coastal region of Lithuania and flows through Plungė and Kretinga districts municipalities. Its source is in the vicinity of Plateliai, 13 km North of Salantai at Samogitian Highlands and it drains into the Minija River next to Kūlupėnai village.

The river and its tributaries Blendžiava, Bubinas and Notė are designated as a NATURA2000 site to protect specific riparian habitats that are made up of mixed, broadleaf forests, Lowland hay meadows, Northern Boreal alluvial meadows, and Fennoscandian lowland species-rich dry to mesic grasslands. These habitats are home to a wide variety of important wildlife such as river lamprey, vimba bream, European bullhead, thick-shelled river mussel and one of the most numerous populations of sea trout.

Project context and opportunity

In the summer of 2021, one of the major dams at Salantai town was demolished. The other, Santakle Weir, is an impassable dam located at Tuzai which is much further upstream. Now, this weir is the biggest obstacle for migrating fish species to reach the most favourable spawning grounds in the river and its tributary Notė.

The dam was built after the third partition of the Polish-Lithuanian Commonwealth in the 1840s – at that time Lithuanian was under the governance of the Russian Empire. According to local knowledge, the existing dam was partly demolished in 1950s for materials that were used to build Šateikiai nuclear missile launching site, from there the nuclear weapon was transported to Havana and caused the Cuban Missile Crisis. However, the USSR army did not remove the concrete weir and it is still intact and disrupts habitat connectivity and sediment transport in the river.

The annual monitoring showed rebounded natural recruitment of salmon in the Minija subbasin and in recent years, the intensive use of spawning habitat in the tributaries. The overall monitoring of salmonid recruitment in the Salantas River below the downstream demolished dam indicates it to be stable and one of the most numerous in Lithuania. Therefore, upstream sections and tributaries of Salantas River are expected to hold a similar potential for migratory fish.

Project aims

Removal of the dam will open access to the most favourable spawning grounds for sea trout, vimba breams, and river lampreys, which are in the river section just above the weir and in the tributaries. The Salantas River also holds the chub population which are potamodromous fish that migrate within the watershed and would get access to numerous spawning habitats. Lastly, the removal of Santekle weir in addition to the already removed Salantai Dam would possibly benefit the salmon population, as would help to naturalize the river bed upstream.

Project achievements

The project restored fish migration and improved the Salantas River ecosystem by removing an obsolete stone weir, formerly used by a watermill. Following the demolition of a major dam in Salantai town in 2021, the weir remained the final significant barrier preventing sea trout, vimba bream, and river lamprey from reaching key spawning grounds. Monitoring had already shown increased salmon recruitment in the Minija sub-basin, suggesting that further restoration would bring additional benefits to fish populations.

The project involved securing permits, gaining access to the site, conducting a baseline assessment of the fish community prior to removal, engaging local stakeholders, and physically dismantling the weir. This reopened over 16 kilometres of river habitat, restored natural sediment transport, and enhanced fish migration routes.

Future monitoring will assess habitat connectivity, salmonid reproduction, and the ecological status of the river. The project provides a strong foundation for long-term ecological recovery and stands as a valuable example of river restoration in Lithuania.