water quality characteristics of barfabad river in kermanshah province

barfabad river is one of the most important surface water resources in the west of iran which passes from the south of kerend and through the islamabad city and receives high volume of human and industrial sewage. for assessing the water quality of the river, 8 stations were chosen and 72 samples were taken during 9 months from april 1997 to january 1998 and were analysed according to the standard methods. sewage of islamabad and kerend cities, with population of 77412 and 10760, respectively, and wastewater of the islamabad sugar factory, and slaughterhouse of islamabad and keredn, discharge into the river without any treatment. due to discharge of islamabad sugar factory wastewater into the river, in november, bod and cod load in the 4th station was 122 and 376 mg/l respectively, in comparison with the first 15 mg/l, showing increases of 15/2 and 25 times, respectively. the least concentration of do was 5 mg/l in november in the 5th station during 9 months, in comparison with the first station which was 7.5 mg/l, cdo decreased 15 times. the highest amount of turbidity was 150 n.t.u. in the 4th station in october, which in comparison with the first station with 15 n.t.u. the turbidity showed an increase of 10 times. in addition, the presence of biological indicators such as sludge worm and leach in the 5th and 7th stations in october and november indicated high level of pollution during those months.