Comparative analysis of water quality index based on seasonal differences in the upstream Citarum watershed

ABSTRACT The Upstream Citarum Watershed is the largest watershed in West Java Province that supports the activities and livelihoods of its surrounding communities. Thus, continuous monitoring of the Citarum River's water quality is essential, with the water quality index (WQI) as an effective tool for assessing its status. Various methods can be used, such as the National Sanitation Foundation WQI (NSF-WQI), the Prati index, and the Dinius index. This study aims to compare these three methods based on secondary data in the form of water quality data from the Regional Environmental Management Agency of West Java Province (2013–2022) collected at four monitoring points, namely, Wangisagara, Koyod, the area after the wastewater treatment plant (WWTP) at Cisirung, and Nanjung. Additionally, primary data from sampling conducted at the same monitoring points were analyzed. The data obtained were categorized based on wet–dry months, wet–dry years, monitoring points, and monitoring years. Based on this study, the water quality status of the Upper Citarum River Basin was obtained in the form of 'Good' and 'Moderate' by the NSF-WQI method; 'Excellent', 'Acceptable', 'Slightly Polluted', and 'Polluted' by the Prati index method; and 'Excellent', 'Good', 'Moderate', 'Bad', and 'Very Bad' by the Dinius index method.