Fresnedillas de la Oliva Wastewater Treatment Plant - Comunidad de Madrid, Spain

The Fresnedillas de la Oliva wastewater treatment plant is located in the Comunidad de Madrid, serving the small municipality of Fresnedillas de la Oliva. The plant provides secondary treatment for a population of 3,136, with a designed capacity of 4,000 m³/day and an average discharge volume of 413.26 m³/day. As a small agglomeration in Spain, the plant operates under the EU Urban Waste Water Treatment Directive 91/271/EEC, which requires secondary treatment for inland freshwater discharges. The plant's secondary treatment level meets the directive's standards for this population tier. The treated effluent is discharged into local watercourses that drain into the Guadarrama River basin, part of the Tagus River watershed. The Tagus River flows westward through Spain and Portugal, eventually reaching the Atlantic Ocean near Lisbon. The plant's operations help protect the ecological health of the Guadarrama River and downstream aquatic habitats.

The plant discharges into local streams that feed the Guadarrama River, a tributary of the Tagus River basin. The Tagus River is the longest river in the Iberian Peninsula, flowing through central Spain and Portugal to the Atlantic Ocean. The watershed supports diverse aquatic life and provides water for agriculture and urban use. The plant's secondary treatment helps reduce nutrient loads and organic pollution, protecting downstream ecosystems and water quality in the Tagus estuary.