BOSSOST Wastewater Treatment Plant, Bossòst, Val d'Aran, Catalunya

The BOSSOST wastewater treatment plant is located in Bossòst, a municipality in the Val d'Aran region of Catalunya, Spain. The plant serves a small population of 415 residents, reflecting the rural and mountainous character of the area. As a facility in a remote Pyrenean valley, it plays a key role in protecting local water quality. As a small agglomeration in Spain, the plant operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires appropriate treatment for discharges into sensitive areas. Spanish regulations typically mandate secondary treatment for inland plants of this scale to meet environmental standards. The treated effluent from BOSSOST is discharged into the local watershed, which drains into the Garona River (Garonne) and ultimately flows toward the Atlantic Ocean via the Gironde estuary. The plant's operation helps preserve the ecological integrity of the Val d'Aran's streams and rivers, which support diverse aquatic life and are important for the region's biodiversity.

The BOSSOST plant discharges into the Garona River basin, which originates in the Pyrenees and flows north into France. The river supports a range of aquatic species, including brown trout and other cold-water fish. Downstream, the Garona joins the Dordogne to form the Gironde estuary, a major ecological zone. Protecting water quality in this headwater region is critical for the health of the entire river system.