AGURAIN Wastewater Treatment Plant, Agurain/Salvatierra, Spain

AGURAIN is a wastewater treatment plant located in Agurain/Salvatierra, within the province of Araba/Álava in the Basque Country (Euskadi), Spain. The facility serves a population equivalent of 4,450, placing it in the small agglomeration category under EU classification. Its address along Zadorra kalea places it near the Zadorra River, a key watercourse in the region. As a Spanish plant serving fewer than 10,000 people, AGURAIN is subject to the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires appropriate treatment for discharges into freshwater and estuaries. For small agglomerations, secondary treatment is typically mandated unless the receiving waters are designated as sensitive areas, which may require more advanced treatment. The plant's operational details and treatment processes are managed by the relevant Basque water authority. The treated effluent from AGURAIN likely discharges into the Zadorra River, which flows into the Ebro River and ultimately reaches the Mediterranean Sea via the Ebro Delta. The Zadorra River supports local aquatic ecosystems and is part of the Ebro basin, a region of ecological importance for migratory birds and native fish species. The plant's role in maintaining water quality is vital for the downstream environment and the broader Ebro watershed.

AGURAIN discharges into the Zadorra River, a tributary of the Ebro River, which flows into the Mediterranean Sea at the Ebro Delta. The Ebro basin supports diverse aquatic life and is an important corridor for migratory birds. The Zadorra River itself provides habitat for native fish species and contributes to the ecological health of the region. Protecting water quality in this watershed is essential for maintaining biodiversity and supporting downstream uses.