OION Wastewater Treatment Plant, Oyón-Oion, Euskadi, Spain

OION wastewater treatment plant is located in Oyón-Oion, a municipality in the province of Araba/Alava within the Basque Country (Euskadi), Spain. The plant serves a population of approximately 3,700 people, classifying it as a small agglomeration under EU classification. As a Spanish facility, OION operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations of this size discharging into freshwater. The plant's treatment processes and capacity details are not publicly available, but the regulatory framework ensures compliance with national and EU standards for effluent quality. The treated effluent from OION likely discharges into the Ebro River basin, which flows into the Mediterranean Sea via the Ebro Delta. The downstream environment includes agricultural areas and ecologically sensitive wetlands, making proper treatment essential for protecting water quality and aquatic habitats.

The OION plant discharges into the Ebro River basin, which drains into the Mediterranean Sea through the Ebro Delta. This delta is an ecologically important area supporting diverse bird species and aquatic life. The plant's location in the Ebro valley, surrounded by vineyards and agricultural land, means treated effluent quality is critical for maintaining downstream water quality and ecosystem health.