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Weir removal takes Long Preston deeps closer to nature

September has been a busy month for Ribble Rivers Trust, with two weir removals, one newly created fish bypass channel, the start of two new fish passage projects, plus the creation of the longest fish pass in England which is still in progress.

The now disused Long Preston weir, created to provide aeration to Settle water treatment works
The now disused Long Preston weir

One of these projects was the partial removal of Long Preston weir. Located on the river Ribble, near the picturesque North Yorkshire town of Settle, Long Preston deeps is a SSSI (Site of Special Scientific Interest) which covers 162 hectares of floodplain.

What makes this site so interesting is the unusual river morphology (a term given to the natural processes, shapes, and directions a river usually follows), as well as the breeding wader birds and aquatic plants.

This weir is a relatively new structure, in comparison with others which were created to power mills during the Industrial Revolution. Long Preston weir was built to provide aeration to the Settle water treatment works some time in the 1970s.

Long Preston weir, following our work to remove the central 60% of the structure
Long Preston weir, following our work to remove the central 60% of the structure

Due to upgrades to the water treatment works it has been some time since the weir was needed, and so Ribble Rivers Trust have partially removed the central 60% of the weir.

The weir, which has a total width of 21 meters and a height of approximately 0.5 meters, is passable to the majority of fish species. However, it does act as a partial barrier and more importantly, it negatively impacts sediment movement and spawning (or breeding) habitats.

In time this work should see an improvement on the hydro-geomorphology (a term which describes the links and interactions between river processes and the land, and vice-versa). This will create a more natural river channel, which should result in greater fish spawning and an overall improvement in fish numbers.

Work in progress on the now completed partial weir removal on the Ribble at Long Preston
Work in progress on the now completed partial weir removal on the Ribble at Long Preston

Throughout the planning of this project we have worked closely with local angling clubs, and next year we plan to further improve habitat here with some woody debris in the channel and some riverside willow planting, which will increase refuse areas and shade for fish.

These projects are part of a series of 10 restoration projects in the Ribble Rivers Trust’s “Ribble Life for Water” programme. These are funded by a Water Environment Grant managed by the Environment Agency coming from the European Agricultural Fund for Rural Development. As part of this programme, in the summer of 2021 Ribble Rivers Trust plan to set-back a section of flood embankment downstream of the weir, to re-connect the river to the floodplain.