La Gavia Wastewater Treatment Plant, Madrid, Spain

La Gavia is a wastewater treatment plant located in the Comunidad de Madrid, serving the city of Madrid, Spain. With a population equivalent of 346,956, it is classified as a large agglomeration under EU regulations. The plant is situated in the Manzanares River basin, which flows through the Madrid metropolitan area. As a large agglomeration, La Gavia is subject to the EU Urban Waste Water Treatment Directive 91/271/EEC, which requires secondary treatment as a minimum and tertiary treatment for discharges into sensitive areas. The regulatory framework ensures that facilities of this scale meet stringent effluent standards to protect water quality. The treated effluent from La Gavia is discharged into the Manzanares River, a tributary of the Jarama River, which eventually flows into the Tagus River and then into the Atlantic Ocean near Lisbon. The Tagus basin supports diverse aquatic life and is an important water resource for irrigation and urban supply in central Spain and Portugal.

La Gavia discharges into the Manzanares River, which flows through Madrid and joins the Jarama River, a major tributary of the Tagus River. The Tagus River is the longest river in the Iberian Peninsula, draining into the Atlantic Ocean. The watershed supports diverse aquatic ecosystems and provides water for agriculture and urban areas. The plant's location in a densely populated region means its effluent quality is critical for maintaining the ecological health of the Manzanares and downstream water bodies.