Restoring River Habitat
‘Restore natural processes and connectivity of rivers and streams to improve habitat for all species’
Rivers and streams are constantly changing environments driven by a number of different natural processes. This constant change creates a huge variety of habitats and many of the niche’s that wildlife needs to survive. Unfortunately, many watercourses of the River Dee have become more uniform after years of management such as dredging, widening of the channel, installing hard bank revetment, removing fallen trees, and intensive grazing of the banks, with resulting impacts on the wildlife of the river.
This programme aims to restore the natural processes which create habitats where wildlife can flourish. This includes interventions such as fencing to allow tree regeneration, preventing excessive erosion, adding woody material to rivers, removing man-made structures, and recreating floodplain features.
Afon Llynor Barrier Case Study
Species that migrate up and down rivers, such as salmon or eels, often find themselves stuck behind, or in front of, barriers. This can lead to adults becoming exhausted before they reach spawning grounds, or smolts (young salmon travelling back to the sea) getting bashed against rocks or trapped and subject to predation as they run the gauntlet to the sea.
This crossing on a tributary of the Dee was causing problems for adult salmon moving upstream to spawn, and potentially causing damage to smolts moving downstream as they are bashed against rocks below the vertical drop. Boulders were moved into the channel to narrow it and create a series of deeper pools, offering a deeper water route across the concrete structure. Once the boulders were in place, gravel was used to fill gaps between them and raise the water level in the pools. Not only does this mean adult fish can get upstream to spawning sites more easily, and therefore with more energy to spawn, it also provides deeper water for smolts as they come over the structure in spring and early summer, easing their journey to the sea.
2022 was a year of flux for the Restoring River Habitat programme as some projects finished and new ones began.
Work funded by Natural Resources Wales for fish habitat improvements delivered a suite of interventions across the Welsh tributaries of the Dee, with a focus on creating good juvenile habitats for salmon and trout. A new project also started in the Aldford Brook catchment in partnership with Severn Trent Water and Cheshire Wildlife Trust. Low flows caused by abstraction for drinking water are damaging the ecosystem of the brook. To help mitigate the impact, Severn Trent Water is funding habitat improvements to benefit the freshwater wildlife of the catchment.
2022 was also a year of identifying and drawing up projects across the Dee catchment and 2023 will see a substantial increase in the number of habitat restoration projects delivered.
Afon Alwen Tributary Case Study
River habitat covers more than just the wet channel. It spans from the floodplain, across the river banks and into the channel. Where possible we try to ensure that we take steps to improve habitats across this whole range of situations. This project on a tributary of the Afon Alwen took steps to improve in channel, riparian (ie bankside) and floodplain habitat. Large woody material was cut and carefully positioned in the river to create diversity of flows providing spawning riffles and cover for fish.
The river bank was fenced to prevent all livestock accessing the water, allowing trees and tall vegetation to flourish along the waters edge. A secondary fence line was also placed further away from the river which allows the farmer to control livestock access to the neighboring floodplain wetland, ensuring just the right amount of grazing to allow the greatest diversity of plants to flourish, and creating space for invertebrates and birds.