There were 2 main objectives for restoration works on the Aghlisk River:
- Installation of 310m of fencing to exclude livestock and create a natural buffer.
- Installation of 150m of bank revetment to combat erosion.
The two sites on the Aghlisk River, a tributary of the Owenreagh, were designed to address severe erosion issues in this area, where entire river banks were collapsing into the river and causing major siltation issues in areas of quality spawning and nursery habitats. This erosion was acerbated by livestock trampling due to the lack of riparian fencing in this area.
Site 1 – Aghlisk
In working towards achieving advances in habitat protection, Loughs Agency installed livestock proof fencing in sections of the Aghlisk River, a tributary of the Owenreagh River. To reduce siltation from erosion impacting upon spawning and nursery habitat, bank revetment works were carried out.
On site 1, 80m of heavy bank side rock revetment was installed using natural round boulders to re-profile the eroded corners and bring the river back to its natural width. These round boulders, placed at a 45 degree angle are most suitable for revetment schemes, as they lock into each other and can sustain flood events, as the river flow drops down through the spaced round boulders, dissipating the energy of the river and slowing the flow.
Natural round boulders are also much more river species friendly than hard engineering with larger rock flags, as they provide ideal habitat for both invertebrates and juvenile salmonid species in their recesses.
Site 2 – Aghlisk
On site 2 of the Aghlisk River, a similar scheme was completed to combat erosion issues, only this time a combination of root wads and round boulder rock was used to keep it in place.
This work reprofiled an area of 70m that had been badly affected by erosion and was visibly impacting adjacent spawning beds and nursery areas. This scheme was complimented by 310m of riparian fencing to exclude livestock from the river bank and recreate a natural buffer strip.
The outcome of these projects includes riparian fencing thus enhancing the in stream habitat and riparian zone. This bank revetment will improve water quality, increase bank stability, reduce erosion risk, support biodiversity, protect invertebrates and indigenous fish populations of the watercourse.
Read the full case study for river restoration works during 2020 on the Drumragh catchment.
