Catchment Significant Pressures Description: The Glaskeelan_010 waterbody has a High Status Objective and is a Blue Dot site. It sits within the Leannan Priority Area for Action for LAWPRO and is one of Irelands Top 8 Freshwater Pearl Mussel Catchments. Forestry was the suspected Significant Pressure identified during Initial Characterisation causing hydrological, morphological and nutrient issues.
Referral point Upstream EPA Monitoring Point ‘Br W of Roshin’.
Forestry (Owner) Coillte
“Referral Significant Issue (s) Description : Existing forestry between Glenveagh National Park and Br W of Roshin is likely to be a pressure based on observations seen during the 2021 surveys. Existing hydromorphological pressures from forestry were observed such as the planting of conifers right up to the bank edge. In several cases, the riverbank was slumping, and sods of earth material were falling into the channel, introducing a source of sediment to the river. Overdeepening of the channel was common, especially in the forested area. Excessive growth of broad leaved macrophytes (Potamogeton sp and Nuphar lutea) were noted where overdeepening has led to a change in flow dynamics from a fast upland river to a sluggish channel. Old forestry drainage channels have direct connectivity to the watercourse, providing a preferential flow pathway for nutrients and sediment. Trash lines were noted in the forestry, and forestry debris such as pine needles will be introduced into the river as floodwater recedes. Measures to reduce the impact of forestry are required for the Glaskeelan. Such measures must be done sensitively (given the importance of the catchment for the protected freshwater pearl mussel and salmonids) and in collaboration with stakeholders. Possible mitigation measures are to be determined by the Forestry Service but could include sensitive removal and or thinning of the conifer plantation, rewetting of the Blanket Peat habitat in which the coniferous forestry stands and allowing natural regeneration of native trees on mineral soils. A Catchment Based Approach to River Restoration to restore the functionality of the watercourse due to historical morphological alterations (overdeepening) is recommended. ‘Anthropogenic – Unknown’ has been suggested as another Significant Pressure affecting the Glaskeelan_010. On 28th July 2021, EPA reported a Red Dot notification for the monitoring point ‘Bridge W of Roshin’ (Lough Gartan). The macroinvertebrate Q dropped three classifications from High to Poor. From 18th to 26th July 2021 – two days before the EPA kick sample, there was a heatwave and western spate rivers such as the Glaskeelan were subjected to nine days of average air temperatures of over 22°C. Several nearby waterbodies (e.g Glentornan, Gweebarra_010, Gweedore_010) surveyed in or just after the heatwave also saw a decline in Q score.
Hydromorphological issues can make temperature stress more intense and pressures such as overdeepening were observed within the forested area of Glaskeelan. It is suspected that the high temperatures along with the hydromorphological issues on the Glaskeelan led to a severe drop in macro-invertebrates leading to the Red Dot notification.”