The study aims to assess the current state of surface water quality in Phung Hiep district, Hau Giang province, Vietnam. Surface water quality data were collected at nine locations (PH1 - PH9) collected at a frequency of 4 times in the year 2020 (March, May, August and October), with surface water quality parameters included temperature, pH, dissolved oxygen (DO), total suspended solids (TSS), nitrite (N-NO2-), nitrate (N-NO3-), ammonium (N-NH4+), orthophosphate (P-PO43-), biochemical oxygen demand (BOD), chemical oxygen demand (COD), coliform and iron (Fe). Surface water quality is assessed by comparing with national technical regulation on surface water quality (QCVN 08-MT:2015/BTNMT, column A1) and by calculating the water quality index (WQI). The results showed that TSS, N-NO2-, N-NH4+, P-PO43-, BOD, COD, coliform, Fe exceeded the allowable limits of QCVN 08-MT:2015/BTNMT, column A1. DO was lower than the regulation while the water quality parameters of temperature, pH and N-NO3- were within the allowable limits. The water indicators of DO, TSS, N-NO2-, N-NO3-, N-NH4+ in the dry season were higher than those in the rainy season while the remaining parameters such as P-PO43-, BOD, COD, coliform and iron in the dry season were lower than those in the rainy season. The WQI values ranged from 24 - 85, showing that surface water quality in Phung Hiep area was poor - good
In which, PH6 location has the best water quality (WQI = 46 - 85)
PH1 (May) and PH7 (August) had poor water quality, mainly due to organic matters, coliform and N-NO2-. Future study needs to investigate the causes of water pollution to have appropriate treatment solutions.