RIOSEQUILLO Wastewater Treatment Plant, Garganta de los Montes, Comunidad de Madrid

RIOSEQUILLO is a municipal wastewater treatment plant located in Garganta de los Montes, within the Comunidad de Madrid, Spain. The plant serves a small population of 641 residents, reflecting its role in a rural or semi-rural community in the Sierra de Guadarrama foothills. The plant provides secondary treatment, which is the standard biological treatment stage required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 10,000 m³/day and an actual discharge volume of 922.52 m³/day, the plant operates well below its capacity, indicating significant headroom for future growth or seasonal variations. The treated effluent is discharged into the local hydrological network, which ultimately drains into the Lozoya River, a tributary of the Jarama River, and then into the Tagus River basin. This water body supports diverse aquatic life and is part of the broader Tagus River ecosystem, which flows into the Atlantic Ocean near Lisbon.

The plant discharges into the Lozoya River basin, which feeds into the Jarama River and then the Tagus River, one of the Iberian Peninsula's major rivers. The Tagus River supports a variety of fish species and provides water for agriculture and urban use downstream. The area is ecologically sensitive due to its proximity to the Sierra de Guadarrama National Park, which hosts diverse flora and fauna.