SAN ILDEFONSO Wastewater Treatment Plant, Parque Robledo, Segovia, Spain

SAN ILDEFONSO is a wastewater treatment plant located in Parque Robledo, within the municipality of Palazuelos de Eresma, Segovia, in the autonomous community of Castilla y León, Spain. The plant serves a population of approximately 15,000 people, placing it in the medium agglomeration category under EU regulations. It is situated inland, away from coastal areas, and its operations are part of the regional wastewater infrastructure managed by local authorities. As a plant serving a medium-sized agglomeration in Spain, SAN ILDEFONSO is subject to the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for discharges into freshwater bodies. The directive also mandates more stringent treatment if the receiving waters are designated as sensitive areas. The plant is expected to comply with these standards to protect local water quality. The treated effluent from SAN ILDEFONSO is discharged into the local watershed, which ultimately drains into the Eresma River, a tributary of the Duero River. The Duero River flows westward through Spain and Portugal before emptying into the Atlantic Ocean. The plant plays a crucial role in safeguarding the ecological health of the Eresma River and the downstream Duero basin, supporting aquatic life and water quality for communities along the river.

The plant discharges into the Eresma River, a tributary of the Duero River, which flows through the Castilla y León region and into Portugal, eventually reaching the Atlantic Ocean. The Duero basin supports diverse aquatic ecosystems, including fish species such as barbel and trout, and provides water for agriculture and human consumption. Protecting this watershed from nutrient pollution is critical to maintaining its ecological balance and meeting EU Water Framework Directive goals.