Removal of barriers in the Szczecin Lagoon catchment: the Wołczenica and Sławęcinka rivers, Poland

Introduction

The Wołczenica and the Sławęcinka rivers are part of the Szczecin Lagoon and Odra River catchments. The lagoon is an important nursery and spawning ground for many fish. Due to the Odra pollution, the tributaries form a vital habitat for migrating fish.

Barrier removal, together with the restoration of proper water relations in the valleys of these rivers, reduces the adverse effects of river regulation and minimises river fragmentation. These small-scale actions demonstrate the benefits of river restoration and contribute to raising awareness among riparian communities, thus forming part of the implementation of the Nature Restoration Law in Poland.

Lowland ecosystems are affected by drought, and bringing back more natural river conditions improves the region’s resilience to the adverse effects of climate change.

Project context and opportunity

From a list of more than ten barriers identified through the previous Open Rivers Programme supported project, three barriers were selected as the most suitable for removal. For each barrier, there is a clear roadmap: the first step is the removal of vertical remnants of concrete structures that cause bottom erosion. The second step is to restore the natural riverbed by introducing gravel prism sequences.

Project aims

The project’s goal is to remove the selected barriers as a key step in opening up the basin under all hydrological conditions. On both rivers, the removal will improve ecological conditions for salmonids and river lamprey.

The Wołczenica river is a very important wintering ground for fry of many fish species, a spawning ground for river lamprey (one of the last rivers where larvae are found permanently), and a spawning ground for sea trout. It is also a rare case of a river flowing through areas rich in calcium compounds (lake chalk). For this reason, morphological connectivity is particularly important.

The Sławęcinka is the first tributary of the Ina river with good environmental quality, located 22 kilometres above the town of Stargard. There are no other spawning tributaries of similar quality, so this removal will provide a ten-kilometre-long tributary with crystal-clear water and water crowfoot habitat, with numerous gravelly sections forming suitable spawning grounds.