The Role of Organic and Microbial Contamination in Surface Water Quality Deterioration in Al-Kut City, Wasit Governorate

Abstract

This investigation systematically evaluates the influence of organic and microbial pollutants on surface water quality within irrigation channels originating from the Tigris River in Al-Kut City, Wasit Governorate, Iraq. Water specimens were collected from two strategically selected monitoring stations—Shatt Al-Karimiyah (Dujaila River) (Station A) and Al-Khajiyya (Station B)—during October 2025. Comprehensive physicochemical and microbiological analyses were conducted in accordance with standard methods. Turbidity concentrations at both stations (52 and 43 NTU, respectively) significantly above allowable criteria, according to analytical results, while Station B's pH levels were below ideal values of 5.6. Abnormally high (BOD5) readings were found, 40 mg/L at Station A and 32 mg/L at Station B, signifying high organic pollution. (COD) values of 44 mg/L and 48 mg/L respectively, give signs of organic and inorganic oxidizable contaminants present.Microbiological analyses showed that there was no residual chlorine at either site, with heterotrophic plate counts exceeding permissible limits (128 and 124 CFU/mL) and total coliform and Escherichia coli concentrations exceeding 8 MPN/100 mL. These empirical findings confirm substantial contamination by organic material and microorganisms, making the water inappropriate for some uses unless it undergoes treatment first.