Dundagas NAI Wastewater Treatment Plant, Dundagas pagasts, Latvia

Dundagas NAI is a municipal wastewater treatment plant located in Dundagas pagasts, Talsu novads, Latvia. The facility serves a population of approximately 1,750, classifying it as a small agglomeration under the EU Urban Waste Water Treatment Directive (91/271/EEC). The plant provides secondary treatment, which meets the minimum standard required by the EU directive for freshwater discharges from agglomerations of this size. With a designed capacity of 1,000 m³/day and an average daily flow of 196.10 m³/day, the plant operates well below its capacity, indicating potential for future growth or seasonal variations. The treated effluent is discharged into the local watershed, which ultimately drains into the Baltic Sea via the Irbe Strait. The region's coastal proximity (within 50 km) means the plant's discharge contributes to the nutrient load in the Baltic Sea, a sensitive ecosystem affected by eutrophication. The plant's secondary treatment helps reduce organic pollutants and suspended solids.

The treated wastewater from Dundagas NAI enters the local river system, which flows into the Irbe Strait and then the Baltic Sea. The Baltic Sea is a brackish, semi-enclosed sea with limited water exchange, making it highly sensitive to nutrient pollution. The plant's secondary treatment reduces biochemical oxygen demand and suspended solids, but does not remove nutrients like nitrogen and phosphorus, which can contribute to algal blooms and eutrophication in coastal waters.