The Ina River – an important tributary of Oder Delta – is a 130 km long lowland river with a 2300 km2 catchment. It is characterized by the presence of water crowfoot habitat from its springs to the mouth and by mid flow (12 m3/s). Its main tributaries are Krąpiel River, Mała Ina River, Stobnica, while smaller ones include the Wisełka and Biała Struga streams (Figure 1).
Several species of ecological importance and/or concern inhabit Ina River catchment, including the Atlantic salmon, sea trout, river lamprey, brown trout, grayling, spined loach, weather loach, bitterling and vimba carp. The Ina River is also of significant economic importance as it is a water source for irrigation purposes and it provides opportunities for recreational activities; for example, it is a popular destination for anglers.
The Ina River has been used as a navigable waterway since the 15th century; the region was part of the Hanseatic League for several centuries. Part of the catchment area, the Pyrzyce Riviera, is one of the most fertile agricultural areas in this part of Europe. This fact left its mark centuries ago, which still affects the condition of the catchment today, especially in a water context.
Over the centuries, mills were built along the Ina River Valley which strongly influenced the ecological state of a 60 km river stretch, from the estuary to Domiąża (i.e., the lower section of the Oder) to Stargard. Until the 1930s the valley above Stargard was used as pasture with minimal intervention, which helped preserve its wetland character and maintain stable water flows. This changed in the mid-1930s, as the riverbed got regulated upstream from Stargard, up to 100 km. Currently, there are about 30 barriers in the Ina River catchment, most of them equipped with fish ladders. Particularly troublesome are the remnants of the mills on the tributaries which remain obsolete impeding fish migration.
The Bącznik Weir (Figure 2), situated at Wisełka Stream near Bącznik Village (Figure 3) was originally installed as part of a watermill. It was built over a century ago, and for the last few decades it had fallen into disrepair. It was part of a private estate. However, the riverbed was not part of it, which allowed the removal of the weir, while adjacent infrastructure remained untouched.
The Bącznik Weir had detrimental effects on fish migration and natural sedimentation for decades. The importance of restoring free flowing conditions on Wisełka Stream and the Ina River catchment in general was assessed during several projects (https://inatarliska.pl/, https://malecieki.pl/) conducted by local Universities, in which Artur Furdyna, the project manager of the removal of the Bącznik Weir, was involved.
Preparations for restoration work on the Wisełka took many years starting in 2004, but final administrative actions and design initiated in 2021. Rewilding Oder Delta, supported by the Association of the Friends of the Ina and Gowienica Rivers (TPRIiG), secured funding, prepared the necessary documentation — including feasibility assessment and analysis, an ecological restoration concept, and a rewilding design — and selected a contractor. The removal works of the weir (Figure 4) as well as the restoration of the riverbed (Figure 5) took place in June 2024.
“We identified ten in-river structures negatively impacting the connectivity of the rivers in the catchment. From these we ultimately selected two for removal. Removing obsolete barriers is a huge opportunity to recreate properly functioning river systems”
Piotr PiotrowskiTPRIiG
The action was supported by the local Forestry District of Kliniska, thanks to longstanding cooperation and effective communication underlining the benefits of the healthier rivers. The total net cost of the project was 40000 euro.
“The removal of barriers and the restoration of the riverbed have improved conditions for the reproduction and migration of many fish species, including sea trout. We are also expecting the return of indicator plant species, such as water buttercup.”
Artur FurdynaRewilding Oder Delta
The main issue encountered during the project was the recognition of the watermill ruins as a monument of cultural heritage, precluding full restoration of the site. An additional, unexpected challenge that had be overcome was the presence of beavers, which actively alter many of the River Ina’s tributaries during times of drought. However, following the removal and riverbed restoration, the beavers quickly adopted to the restored site. It is hoped that future restoration measures will also align with the needs of the beaver population in the area.
The removal of the Bącznik Weir at Wisełka Stream, along with the removal of another weir at Biała Struga, complemented by efforts to recreate more natural riverbed conditions, enhanced fish migration and reproduction along 20 km of waterway in River Ina tributaries. The beneficial impact of the removals was visible almost immediately. Only a day after the reopening of those river stretches, river lampreys were seen migrating towards upstream waters (Figure 6, Video 1).
It is expected that the removal and riverbed restoration will enable the return of valuable plant and animal species in the area, but also benefit people. By slowing the current, and boosting the capacity of the rivers to clean themselves, the water quantity and quality in this part of the catchment will be improved. This will enhance natural conditions in the respective stream, but in the surrounding forests and agricultural areas too. The restoration team estimates an extra 3000 m3 of water to be retained in the rivers, and an extra 4500 m3 in their valley. Full monitoring of rewilding activities in the region to also assess the impact of the weir removals will be implemented in the coming years.
More information is available on the following site:
https://rewildingeurope.com/news/rewilding-efforts-breathe-new-life-into-oder-delta-waterways/
Before & After photo pair
With many thanks to Agnieszka Soboń and Artur Furdyna from Rewilding Oder Delta for providing the information and the visuals presented herein.
Prepared by Foivos A. Mouchlianitis