Geospatial Assessment of Water Quality of Pasig River Using Physico-Chemical Parameters and Water Quality Index

Abstract

The Pasig River plays a crucial role in the economy of the city as it serves as means of transport, supplies water for households and industries, and offers recreational opportunities. Moreover, it connects the two major water bodies in Metro Manila: the Laguna de Bay and Manila Bay. Unfortunately, it also serves as a sink for industrial and domestic wastes in the metro. This paper attempts to characterize the Pasig River using Water Quality Index (WQI) and examine the spatial distribution of water quality parameters. Data used in computation of WQI are from analyses of physico-chemical parameters which include DO, BOD, fecal coliform, pH, temperature, TSS, phosphate, nitrate and ammonia from 2020 to 2022. Computed CCME-WQI values of Pasig River ranged from 30.3 to 38.9 with an average score of 33.9 which indicate that the water quality is “poor” across all stations. Findings suggest that the river's physico-chemical characteristics no longer comply with the river system's present waterbody classification, making it unsuitable for its intended purpose for fishery, recreational (Class II), agriculture, irrigation and livestock watering. Further, WQI scores show lowest values in the midstream to middownstream portions of the river, suggesting these sections as having the poorest water quality or areas of critical concern.