BALA WWTW STW - Secondary Wastewater Treatment Plant in Llangywer, Gwynedd, Wales

BALA WWTW STW is a wastewater treatment works located near Llangywer in Gwynedd, Wales, within the Snowdonia National Park. The plant serves a population of approximately 2,158 and operates under the regulatory framework of the UK Environment Agency, which enforces discharge standards under the Water Resources Act and the Urban Waste Water Treatment Regulations (transposing the EU Urban Waste Water Treatment Directive). The plant provides secondary treatment, a standard level for agglomerations of this size in the UK. Its designed capacity is 2,587 cubic meters per day, with a current discharge volume of 480.45 cubic meters per day, indicating operational headroom. The facility is operated as part of the national wastewater infrastructure managed by Dŵr Cymru Welsh Water. The treated effluent is discharged into the local watercourse, which flows into Bala Lake (Llyn Tegid), the largest natural lake in Wales. From there, the Dee River carries the water through the Dee Valley to the Dee Estuary and ultimately into the Irish Sea. This catchment supports diverse aquatic life, including salmon and otter populations, and is an important ecological corridor in the region.

The plant discharges into the Dee River catchment, which flows through Bala Lake (Llyn Tegid) and the Dee Valley before reaching the Dee Estuary and the Irish Sea. This watershed supports a range of aquatic species, including Atlantic salmon, sea trout, and European otter, and is designated as a Site of Special Scientific Interest (SSSI) for its ecological importance. The estuary provides critical habitat for migratory birds and fish.