Bacteriological and physicochemical evaluation of Ergene river water quality

In this study, the spatial and seasonal variations of physicochemical and bacteriological water quality parameters were evaluated based on monitoring conducted at five stations—Ulaş, Esenler, Yukarı Sevindikli, Aşağı Sevindikli, and Ballı Hoca—along the Ergene River during April and November 2024. The main objective of the research was to determine the current water quality status of the river, assess the extent of organic and microbiological pollution, and reveal the overall pollution pressure on the basin using up-to-date scientific data. The findings demonstrated that the Ergene River is exposed to significant pollution pressure, particularly in its middle and lower reaches. High levels of Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Suspended Solids (SS), and turbidity detected at the Aşağı Sevindikli, Ballı Hoca, and Esenler stations indicate the combined influence of both point sources—such as industrial discharges and untreated domestic wastewater—and diffuse sources, including agricultural runoff and surface erosion. A noticeable increase in COD and BOD during the November sampling period was associated with reduced river flow and decreased dilution capacity under low-discharge conditions. Bacteriological analyses revealed fecal indicator bacteria levels exceeding 100 cfu/mL at all stations, indicating that the Ergene River poses a significant hygienic risk and is unsuitable for recreational use. Overall, water quality assessment revealed that the Ergene River largely corresponds to Class III (polluted water) according to the Yerüstü Su Kalitesi Yönetmeliği (2012). This classification reflects substantial ecological stress and highlights potential risks to public health. Based on these results, it is recommended that pollution-control measures in the basin be strengthened, advanced treatment technologies be expanded, diffuse agricultural pollution be reduced through controlled fertilizer and pesticide use, and continuous monitoring programs be enhanced. The study underscores that the Ergene Basin remains an environmentally critical region requiring integrated and sustainable water management strategies.