Abstract:
This study was conducted to determine water quality status and water quality index of Batang Arau River in Padang City, West Sumatera Province, Indonesia by using Pollution Index (PI) and NSF-WQI method. Water samples were collected from six stations along the main river and thirteen selected parameters were analyzed, namely: Temperature, Turbidity, total suspended solid, total dissolved solids, pH, dissolved oxygen, biological oxygen demand, ammonia, nitrates, nitrites, Total Phosphates, Fecal coliform and chemical oxygen demand. Based on the calculation, without including fecal coliform as a parameter, it is obtained that the water quality status in the upstream part, station 1 and 2, have a good water quality criteria (PI value 0.58 and 0.61). Meanwhile, the middle stream part, station 3 and 4, belong to a moderately polluted criteria (PI 5.97 and 5.65), and the downstream part, station 5 and 6, go into a polluted criteria (PI 5.97 and 5.65). The Water Quality Index shows a good category on stations 1, 2 and 3 (NSF-WQI values in the range 71.89-72.44), whereas at stations 4, 5 and 6 fall into a medium category (NSF-WQI value at 63.87-68.48). When fecal coliform is included, there is a decline of water quality status and index of Batang Arau River. The water quality status indicates a moderately polluted at station 1 (PI : 2.07) and polluted on station 2, 3, 4, 5 (PI value in range 5.63-6.06). The Water Quality Index shows medium category in all monitoring stations (NSF-WQI score in the range 54.65-63.32). It is expected that the research results can be used to improve the quality of Batang Arau River.
