Assessment of Escherichia coli Levels in Vjosa River using Standard Microbiological Indicators

Abstract

The Vjosa River one of the few wilde large European rivers is increasingly exposed to human-driven pressures may put at risk its microbial quality. This study estimate the surface-water microbiological status of the Vjosa using Escherichia coli (E. coli) as a primary indicator of faecal contamination. Sampling was performed between October 2024 and October 2025 at 13 locations (seven on the main channel and six on tributaries) in accordance with ISO 19458 for water-quality microbiology. E. coli concentrations were determined by using the Most Probable Number (MPN) method following ISO 9308-1:2014. The results showed contamination in different areas of the river. Average E. coli levels resulted between Class I-II (slight to moderate pollution), yet the several sites repeatedly reached Class III levels (severe pollution), especially in the catchments of Sites 03, 11, 13, 15, and 16. These hotspots are ralated to sites impacted by untreated wastewater discharges, agricultural runoff, and animal activities. A strong positive correlation is between E. coli and intestinal enterococci confirmed that the contamination is originated from faecal sources. Vjosa River generally maintains a moderate microbiological quality, episodic episodes of intense faecal input create public-health concerns. High concentrations of E. coli, total and faecal coliforms, and enterococci render the water unsuitable for recreation or drinking. The study underscores the value of E. coli as a rapid proxy for overall microbial safety and recommends sustained monitoring together with improved catchment-area management to curb faecal pollution in the river’s surface waters. 

CONFLICT OF INTEREST

The authors declare no conflict of interest.

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