Hinterstoder Wastewater Treatment Plant, Mitterstoder, Oberösterreich

The Hinterstoder wastewater treatment plant is located in Mitterstoder, a locality in the municipality of Hinterstoder, Bezirk Kirchdorf, Oberösterreich, Austria. It serves a population of approximately 3,885 people, placing it in the small-to-medium agglomeration category under Austrian and EU regulations. The plant employs advanced treatment processes, which go beyond the secondary treatment standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for sensitive areas. With a designed capacity of 9,000 m³/day and an actual discharge volume of 709.53 m³/day, the plant operates well below its capacity, indicating room for future growth or seasonal variability. The treated effluent is discharged into local watercourses that drain into the Steyr River, a tributary of the Enns River, which ultimately flows into the Danube River and then the Black Sea. The plant's advanced treatment helps protect the sensitive alpine aquatic ecosystems in the region, supporting biodiversity and water quality in the Danube basin.

The plant discharges into the Steyr River catchment, which flows into the Enns River, a major tributary of the Danube. The Danube ultimately reaches the Black Sea. The region is characterized by alpine and pre-alpine environments, with sensitive aquatic habitats that require high water quality. Advanced treatment at Hinterstoder helps reduce nutrient loads and protect downstream ecosystems, including fish spawning grounds and migratory corridors.