Lyse Wastewater Treatment Plant, Łyse, Mazowieckie, Poland

The Lyse wastewater treatment plant is located in the town of Łyse, within the gmina Łyse in powiat ostrołęcki, województwo mazowieckie, Poland. It serves a population of 761 residents, making it a small-scale municipal facility. The plant is situated inland, away from coastal areas, and its operations are part of the local water management infrastructure. As a secondary treatment plant, Lyse meets the standard requirements for biological treatment of wastewater, which is typical for small agglomerations in Poland. The plant has a designed capacity of 4,426 m³/day, though current discharge volume is 108.51 m³/day, indicating significant spare capacity. Under Polish regulations implementing the EU Urban Waste Water Treatment Directive, secondary treatment is the minimum requirement for discharges to freshwater bodies. The treated effluent from Lyse is discharged into local watercourses that eventually drain into the Narew River, a major tributary of the Vistula River, which flows into the Baltic Sea. The plant plays a key role in protecting the local watershed from untreated sewage, supporting water quality in the region's rivers and downstream ecosystems.

The Lyse plant discharges into small streams that feed into the Narew River, a significant waterway in northeastern Poland. The Narew flows into the Vistula, which ultimately reaches the Baltic Sea. The local watershed supports diverse aquatic life and is part of a region with important natural habitats. Protecting water quality here helps maintain the ecological balance of the river system and reduces nutrient loads to the Baltic Sea.