Caldelas Wastewater Treatment Plant, Amares, Portugal

Caldelas is a wastewater treatment plant located in the parish of Caldelas, within the municipality of Amares in the Braga district of Portugal. The plant serves a population of approximately 2,100 people, classifying it as a small agglomeration under Portuguese and EU regulations. It is situated inland, more than 10 km from the coast, and discharges treated effluent into the local watershed. The plant provides secondary treatment, which is the minimum standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for freshwater discharges from agglomerations of this size. The designed capacity is 2,621 m³/day, and the current discharge volume is 350.13 m³/day, indicating ample reserve capacity. As a small inland plant, it is subject to national permitting under Portuguese environmental authorities, which enforce compliance with discharge standards for organic matter and suspended solids. The treated effluent likely enters a tributary of the Cávado River, which flows through the Minho region and ultimately discharges into the Atlantic Ocean near Esposende. The Cávado basin supports diverse aquatic life and is an important resource for agriculture and recreation. The plant's secondary treatment helps protect downstream water quality and the ecological health of the river system.

Caldelas WWTP discharges into the Cávado River basin, which drains into the Atlantic Ocean. The Cávado River supports diverse freshwater and estuarine ecosystems, including fish species such as trout and migratory species. The plant's secondary treatment reduces organic pollution and nutrient loads, helping to maintain water quality in the river and downstream coastal areas.