The Timok River (202 km long, 4547 km2 basin area) is located in East Serbia. It is a right tributary of the Danube River and one of the most polluted watercourses in Serbia. On the basis of the data provided by the Republic Hydrometeorological Service of Serbia, the paper presents an analysis of water quality and pollution using the combined physico-chemical WPI index (Water Pollution Index) calculated for two periods - 1993-96 and 2006-2009 at four hydrological stations: Zaječar-Gamzigrad (Crni Timok River), Zaječar (Beli Timok River), Rgotina (Borska Reka River) and Čokonjar (Timok River). The following parameters were taken into consideration: dissolved O2, O2 saturation, pH, suspended sediments, Five Day Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (CODMn), nitrites, nitrates, orthophosphates, ammonium, metals (Cu, Fe, Mn, Hg, Ni, Zn, Cd), sulphates and coliform germs. The average WPI values were calculated for the observed periods based on the comparison of the annual average values of the listed parameters and defined standard values for the I water quality class (according to the Regulation on the Hygienic Acceptability of Potable Water of the Republic of Serbia). The highest pollution degree was recorded in the Borska Reka River, where heavy metal levels (especially manganese and iron) were significantly increased. These metals are indicators of inorganic pollution (primarily caused by copper mining). Also, increased values of the organic pollution indicators (ammonium, coliform germs, Five-Day Biological Oxygen Demand - BOD5) in the Borska Reka and the Timok rivers are the result of uncontrolled domestic wastewater discharge.
This study aims to assess the water quality and determine the pollution index of the Bedadung River in the urban-area segment of Jember Regency, East Java. The sampling in the urban segment of Jember was conducted in May 2019 at five different locations, namely Slamet Riyadi Street, Mastrip Street, Bengawan Solo Street, Sumatra Street, and Imam Bonjol Street. The pollution index assessment refers to the Decree of the State Minister for the Environment of Indonesia Republic number 115 of 2003. The analysis showed that the parameters of TDS, TSS, pH, COD, BOD, NH3-N, Co, Cd, Cu, Zn, H2S, Cl–, SO4, oil and fats, MBAS, NO2-N, Fe, Pb, F, Cl2, NO3-N, phenol, and As did not exceed the quality standards. The parameters PO4, CN, total coliform, and faecal coliform were found to breach the quality standards at the 5 water sam-pling points. Total coliform and faecal coliform were the dominant pollutants in this segment. Therefore, the parameters of PO4, total coliform, and faecal coliform were considered as indicators of pollution arising from domestic and agricultural activities. The pollution index values for the five sampling locations ranged from 7.21 to 8.23. These scores indicate that the Bedadung River section that passes through the urban segment in Jember is classified as being in the moderately pollut-ed category. This preliminary rapid assessment is therefore one of the considerations for the management of water quality in the Bedadung River section that passes through the urban area of Jember.