]> 2026-04-09T19:52:25+00:00 Case study:Ddu Restoration Project 500 en Phase 5 works summary.pdf 2015 works completed Draft Less than 0.5 m Less than 2 m Boulder restoration Addition of substrate and in channel features Creation of fish passes Natural Resources Wales Snowdonia National Park Authority Welsh Government Yes No Yes false 1996dredgingdamage.jpg 1996damagedsection.jpg Sept2005-machineworking.jpg Sept2005-before.jpg Sept2005-after.jpg 2009Restored section.JPG Partialbarrier.JPG Partialbarrierameliorated.JPG Restoredsection2006.jpg Gravelreintroduction.JPG 2016RestoredSection.JPG 2016RestoredSectionbefore.JPG 2016SectionBeforedownstream.JPG 2016SectionAfterdownstream.JPG No Landowner buy in and suitable catchment management is essential, and there is a good uptake of the Welsh Government's Glasdir Agri-Environment scheme in this small catchment. Successful captive rearing of juvenile mussels at the NRW Aquaculture Unit at Cynrig is considered to be an important future development to secure the future of the species. Due to the sensitive species present in this river, a spread out one step at a time approach to restoration has been appropriate. 52.960248568848,-4.1413209613545 Huw Jones Huw Natural Resources Wales Jones Agricultural business changed its way of working Less than 0.1 m³/s Boulder restoration, Addition of substrate and in channel features,,Fencing of riparian zone,,Creation of fish passes, Deculverting,Agricultural business changed its way of working,,, Long term monitoring of Margaritifera margaritifera numbers in this river indicate a continuing decline in adult numbers, in common with other Welsh rivers. In the Afon Ddu, this has been mostly linked to unsuitable river habitat, both due to physical modifications and some issues with water quality. Monitoring of the success of the restoration work will in future be linked to NRWs use of the Redox potential measuring technique to determine the quality and cleanliness of the interstitial gravel which the juvenile stage of Margaritifera margaritifera rely upon. Monitoring indicates that the encystment stage of the Margaritifera margaritifera is occurring normally in this river, and that juvenile salmonid host numbers are good. Deculverting 23814 Snowdonia National Park Authority, Welsh Government Restoration of the river Restoration2016.JPG 2005-06-01Z 2453522.5 In progress This river was badly damaged by dredging / drainage operations in 1995-6. Investigation work led to the discovery of a previously unknown population of Margaritifera margaritifera - the population was badly damaged by this work. Work to restore some sections of the Afon Ddu has been carried out by legacy Environment Agency Wales and Countryside Council for Wales and partner organisation Snowdonia National Park Authority since 2005. The bulk of this work concentrated on fencing out the river to reduce livestock access, but a short section of the most damaged section was restored in 2006. The river was designated as a pearl mussel Site of Special Scientific Interest in 2010/11. Since the formation of Natural Resources Wales, further work has been carried out with the aim of restoring in channel geomorphology, through the replacement of boulders and gravel seeding with an objective of improving the habitat for salmonids and Margaritifera margaritifera. The small catchment size means that close co-operation with landowners is likely to be more effective than in larger, dispersed, catchments in terms of achieving water quality objectives. Approx. £90,000 has been spent on fencing and habitat works on this river since 2005 by the partner organisations. This river is an UK Biodiversity Plan Priority River for Margaritifera margaritifera, along with two other Welsh rivers. Ddu Restoration Project ddu restoration project Yes Fencing of riparian zone UK - Site of Special Scientific Interest Afon & Llyn Du afon & llyn du Freshwater pearl mussel (Margaritifera margaritifera) Fisheries Habitat and biodiversity Hydromorphology Land use management - agriculture Monitoring GB110065053690 Cwmystradllyn 2018-11-27T16:35:07Z 2458450.1910532 2018-11-28T17:15:22Z 2458451.2190046 Ddu Restoration Project