Castro-Urdiales Wastewater Treatment Plant, Cantabria, Spain

The Castro-Urdiales wastewater treatment plant is located in the municipality of Castro-Urdiales, Cantabria, on the northern coast of Spain. It serves a population of around 54,176 residents, classifying it as a medium-sized agglomeration under EU classification. The plant is situated in the El Rabanal area, near the Alto de San Andrés, and plays a key role in managing the region's wastewater. As a plant operating under Spanish and EU regulations, it is subject to the Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations of this size. The facility is expected to meet effluent standards for coastal discharge, given its proximity to the Bay of Biscay. The treated effluent is discharged into the coastal waters of the Bay of Biscay, part of the Atlantic Ocean. This area supports diverse marine life and is important for local fisheries and tourism. The plant's operation helps protect the coastal environment from nutrient pollution and pathogens, contributing to the ecological health of the Cantabrian Sea.

The plant discharges into the Bay of Biscay, a productive marine ecosystem in the Atlantic Ocean. The coastal waters near Castro-Urdiales support diverse marine life, including fish, mollusks, and seabirds. Proper treatment is essential to prevent eutrophication and protect bathing water quality, which is vital for tourism and local fisheries.