Study of the Water Quality of the Atrak River Using NSFWQI

WQI is one of the most important and easiest methods of determining the water quality of a river because it gives the analyst a clear vision regarding the trend and manner of changes in pollution at a specific time, place and of prevailing conditions. This helps responsible authorities to find crisis points and to figure out suitable, early, and timely solutions for the crises. The presence of important population, industrial, and agricultural centers around the Atrak River and the warm and dry weather conditions in the region have increased the importance of this water source. In this research, the nine parameters of NO3, PO4, FC, T, TS, pH, BOD5, DO, and turbidity were measured at upstream, mid-stream, and downstream stations along 90 kilometers of the river course at one high flow and one low flow season. Standard rules and methods were used in the measurements, and the results obtained were analyzed by employing the software NSFWQI to determine the quality status of the river Atrak situated in the province of northern Khorassan. The average calculated water quality indices at stations upstream, mid-stream, and downstream of the river course were 56.77, 57.66, and 57 in the high water season, and 54, 55, and 55.5 in the low flow season. According to the NSF Index Table, the water at all of the stations was of average quality, which means it is not suitable for drinking or for agriculture. Moreover, at most of the stations, the water is of better quality during the high water season than during the low water season. Furthermore, coliforms and TS are the two parameters that play a role in lowering the quality of the water at both the high water and at the low water seasons. The effect of fecal coliforms in reducing the quality of the water indicates that the river may be polluted by urban and rural wastewater, and that this situation must be controlled.