Holtsee Wastewater Treatment Plant, Lehmkuhl, Schleswig-Holstein

The Holtsee wastewater treatment plant is located in Lehmkuhl, a locality within the municipality of Holtsee in the Hüttener Berge area of Schleswig-Holstein, Germany. The plant serves a population of 12,500 and operates with advanced treatment technology, reflecting Germany's high standards for wastewater management. Its designed capacity is 7,500 m³/day, with an average daily discharge volume of 682.51 m³/day. As an advanced treatment facility, Holtsee goes beyond secondary treatment to remove nutrients such as nitrogen and phosphorus, which is typical for plants in sensitive catchment areas under the EU Urban Waste Water Treatment Directive. This level of treatment helps protect water quality in the region's rivers and ultimately the Baltic Sea. The treated effluent from the plant is discharged into local watercourses that drain into the Baltic Sea via the Schlei or the Eckernförde Bay. The region's aquatic ecosystems benefit from the advanced treatment, which reduces eutrophication risks and supports biodiversity in the coastal waters of Schleswig-Holstein.

The plant discharges into small streams that flow toward the Baltic Sea, likely via the Schlei inlet or Eckernförde Bay. The Baltic Sea is a brackish water body sensitive to nutrient inputs, where advanced treatment helps mitigate algal blooms and oxygen depletion. The surrounding Hüttener Berge area features moraine landscapes and lakes that contribute to local groundwater recharge.