2026 Microbiological quality of the Velika Morava River: Ecological and public health aspects Abstract: Microbiological parameters represent important indicators of water quality and ecological status in river systems. This study evaluates the microbiological quality of the Velika Morava River (Serbia) at its confluence with the Danube during the period 2015–2020, with particular emphasis on seasonal variability. Key parameters included heterotrophic bacteria, aerobic mesophilic bacteria, total and fecal coliforms, Escherichia coli, and Enterococcus spp., analyzed according to ISO and standard microbiological methods. The results indicate that the river predominantly exhibits moderate ecological status (Class III), observed in 67% of samples, while poor status (Class IV) was recorded in 17% of cases. Elevated levels of fecal indicators, particularly E. coli, confirm continuous anthropogenic pressure from untreated wastewater and diffuse sources. Seasonal analysis shows that higher variability and maximum values of microbiological parameters occur during the spring period, primarily due to surface runoff and increased pollutant transport, while during low-flow conditions in late summer, reduced variability but sustained elevated values reflect the dominant influence of temperature and limited dilution capacity. Despite significant organic and fecal pollution, the dominance of oligotrophic bacteria (FO/H > 1) indicates a moderate self-purification potential of the river system. Keywords: microbiological indicators, Velika Morava, seasonal variability, fecal pollution, self-purification. Obradović, Vesna Perović, Marija Vučković, Tanja http://creativecommons.org/licenses/by-nc-nd/4.0/legalcode Proceedings - 32nd International Conference Ecological Truth & Environmental Research – EcoTER'26, June 24-26, 2026, Sokobanja, Serbia startpage: 106 endpage: 111 microbiological indicators, Velika Morava, seasonal variability, fecal pollution, self-purification. application/pdf 2772379 bytes University of Belgrade – Technical Faculty in Bor, Bor, Serbia eng https://unilib.phaidrabg.rs/o:10142 ISBN: 978-86-6305-171-3 info:eu-repo/semantics/conferenceProceedings