Seán Keane

Pollution from a municipal sewage discharge into a salmonid and lamprey stream in Co. Roscommon. This recent video documents the ecological conditions in the receiving watercourse. The video begins upstream of the discharge, where the stream supports clean gravel substrates and stands of Water-crowfoot (Ranunculus sp.) and Water-starwort (Callitriche sp.). These pollution-sensitive plants are indicators of good water quality and are characteristic components of the EU Annex I habitat type 3260. Within metres of the outfall, the stream undergoes a dramatic ecological deterioration. The diverse upstream aquatic community is replaced by one dominated by only the most pollution-tolerant invertebrates, resulting in the lowest possible biological water quality classification: Q1 – Bad. Filamentous algae, cyanobacteria and sewage fungus become widespread. A warning sign on the first downstream bridge advises the public to avoid contact with the river, highlighting the seriousness of the pollution. This warning sign is about the watercourse – not the actual outfall. Although there is some downstream recovery, the effects of nutrient enrichment and eutrophication persist for several kilometres. The final two clips show the Bella River approximately 5 km downstream, at an Environmental Protection Agency (EPA) water quality monitoring station. This site was assigned an unpolluted Q4 (Good Status) rating in 2024. However, the heavily eutrophic conditions now apparent are difficult to reconcile with that classification. The wastewater discharge is considered likely to be a significant contributor to cumulative nutrient enrichment within this catchment. Further downstream, the river system flows into Lough Gara, which is designated as a Special Protection Area (SPA) under the EU Birds Directive. The lake is also an important public water supply source for north Roscommon, with water abstracted from its lower basin. Water quality in this area is also affected by pressures from agriculture, forestry and peat harvesting. Hydromorphological alteration is another significant pressure. This sub-catchment was dredged and channelised as part of the Boyle Arterial Drainage Scheme between 1982 and 1992 and has never fully recovered. Addressing diffuse pressures from agriculture, forestry and historical drainage works is both difficult and costly. Municipal wastewater treatment plants, however, are regulated point-source discharges that should not be causing severe ecological deterioration, warnings for the public to avoid contact with the receiving river, downstream impacts on a public drinking-water source, or a pollution pathway to a Natura 2000 site. The conditions documented in this video should not exist in a regulated municipal wastewater system. They are not consistent with the objectives of the Water Framework Directive or with the protection of downstream Natura 2000 sites. Our rivers, wildlife and communities deserve better.