Markt Indersdorf OT Niederroth Wastewater Treatment Plant, Sigmertshausen, Bavaria

Markt Indersdorf OT Niederroth is a wastewater treatment plant located in Sigmertshausen, a district of Röhrmoos in the Landkreis Dachau, Bavaria, Germany. The plant serves a population of 2,275 and has a design capacity of 2,500 m³/day, with an average discharge volume of 575.75 m³/day. It operates under the German water management framework, which implements the EU Urban Waste Water Treatment Directive (91/271/EEC). For agglomerations of this size (2,000-10,000 population equivalent), the directive requires secondary treatment, which this plant provides. The plant's treated effluent is discharged into local watercourses that drain into the Danube River basin, ultimately reaching the Black Sea. The surrounding region is characterized by agricultural land and small settlements, with the plant playing a key role in protecting local groundwater and surface water quality.

The plant discharges into small streams that flow into the Amper River, a tributary of the Isar, which joins the Danube near Deggendorf. The Danube then flows into the Black Sea. The local watershed supports diverse aquatic life and is part of a region with sensitive groundwater resources. The plant's secondary treatment helps reduce organic load and nutrients, protecting downstream ecosystems from eutrophication.