Over the past year, the North Wales Rivers Trust have been hard at work unlocking nature’s routes with four exciting projects aimed at helping migratory salmonids. Our team has tackled major obstacles in North Wales rivers, opening new pathways for atlantic salmon, sea trout, brown trout and eels as well as coarse (non-migratory) fish. These innovative projects—each a unique solution to a specific barrier—are already making a difference, with migratory fish able to access historic spawning grounds.

1. Larch Wood Baffle Scheme on a Tributary of the Afon Elwy

Our first project took place in the Afon Clwyd catchment, where we installed a series of wooden baffles on a tributary of the Afon Elwy. These baffles, crafted from durable larch wood, were strategically placed at a heavily modified area of the river, which has been over widened, to slow water flow and increase depth in a section of the river that struggled to support fish passage during low flows. By redirecting and deepening the water at key points, the baffles make it easier for migratory salmonids to navigate upstream, even during dry spells. The use of natural materials like larch wood makes for a durable intervention as larch is naturally water resistant.

2. Rocky Ramp on the Nant Garreg Ddu

Next, we took on the challenge of restoring fish passage on a weir located on the Conwy catchment. Drawing on our experience with nature based solutions, we built a rocky ramp designed to mimic the river’s natural flow patterns and stepped-pool appearance. By using a combination of locally sourced stones and boulders, we created a series of gentle steps, allowing salmon and sea trout to navigate upstream with ease, essentially spreading out the height of the weir (~1.2m) over a distance to make each jump far more manageable. This project was inspired by nature itself, using the structure of riffles and pools to guide fish over the obstacle while maintaining the river’s natural aesthetics. Rocky ramps like this are proven to provide effective passage for fish, even during varying flow conditions, making them an ideal solution for this barrier.

The rocky ramp was only implemented in August, yet the height of the weir has already been halved, making it much easier for salmonids to pass upstream!

3. Weir Removal on a Tributary of the Afon Conwy

Our third project took place on a tributary of the Afon Conwy, where a historic weir beneath a crossing bridge was creating an insurmountable barrier for migratory fish, particularly in low-flow conditions. To restore the river’s connectivity, we opted to seek to remove this weir. This tributary was a historic hotspot for salmon in particular but also for sea trout. Removing this barrier should provide good access to the upper reaches of this river. Due to conducting some surveys and preserving this structure by record, the NWRT seek to remove this weir at the start of in-river season 2025, keep your eyes peeled for this one!

4. Investigating a Large Boulder Weir in the Conwy Catchment

In addition to our completed projects, we’ve embarked on a new initiative in collaboration with the geomorphological consultancy group, Socotec. This project focuses on a large 2-metre-high boulder weir located in the Conwy catchment. Although the purpose of this weir is unclear, it currently acts as a complete barrier to fish migration, blocking access to over 7 kilometres of high-quality forested habitat for salmonids.

What makes this project particularly promising is the presence of bedrock downstream of the weir, which actually makes its removal easier. The bedrock ensures that the change in head difference following the weir’s removal won’t cause vertical migration (incision) of the riverbed, and it will also help maintain bank stability. Working with Socotec, we’re currently assessing the sediment accumulated behind the weir and to find out the structure of the bedrock present underneath this loose sediment. This will inform our next steps. This investigation will guide us in determining the best approach to restoring fish passage and reopening this vital stretch of river for salmonid migration.

A Brighter Future for North Wales’ Rivers

These four projects represent a significant step forward in restoring the natural flow of our rivers and supporting the life cycles of migratory salmonids. We have already improved passage to over 7 km of river habitat so far this year!

This work is being completed thanks to fisheries mitigation funding in partnership with Cyfoeth Naturiol Cymru / Natural Resources Wales