Evaluation of bacterial contamination of surface waters of the Gargar River based on global standards

The Gargar River is the eastern brunch of the Karoon River, which is separated in north of Shoushtar by regulatory dam (Bandmizan) from its western branch, Shotaeit, and is about 78 km later, join to the Shotaeit and Dez and create the big Karoon. This river, while supplying drinking water to Shoshtar, Haftgel, and part of Ramhormoz and its villages, is one of the great poles of the province's fish culture. The aim of this study was to evaluate the microbial quality of surface waters of the Gargar River, compare the microbial contamination at upstream and downstream stations as well as comparisons with EPA standards to determine different uses. For this purpose, 6 stations were selected and sampling was conducted monthly within one year and microbial indices including total bacterial count, total coliform count and fecal coliform count were evaluated. The results showed that maximum of the 3 microbial indicators was at the station 2, after the sewage discharge of Shushtar (respectively 15.24×103 CFU/mL, 68181.82, 3380.91MPN/100mL) and the minimum value was at the station 1 at the upstream river (respectively 2.8×103 CFU/mL, 2627.27, 1062.73MPN/100mL). The microbial indices varied depending on seasonal variation, sampling time and location and the final results of this study showed that the water quality of river is inferior and not suitable for human use.