Struma River fish kill caused by wastewater discharge in Kyustendil

The West Sea Basin Directorate has identified the cause of a mass fish kill in the Struma River near the villages of Girchevtsi and Tarnovlag. Investigations revealed that the incident was caused by an unregulated, sudden discharge of large quantities of untreated domestic wastewater and sludge from the Kyustendil municipal wastewater treatment plant.

The pollution entered the Struma River via the Banshtitsa River, which flows into the Struma just before reaching Girchevtsi. Monitoring conducted by the Executive Agency on Environment through eight water samples showed that surface water quality failed to meet ecological standards. Significant excesses were detected in ammonium nitrogen, orthophosphates, total phosphorus, nitrate nitrogen, nitrite nitrogen, and total nitrogen, as well as specific pollutants including copper, manganese, and aluminum.

Despite the surface water contamination, testing confirmed that groundwater quality in water intake facilities for drinking and domestic use along the Dragovitska and Struma river terraces remains fully compliant with safety standards.