ASSESSMENT OF THE SPATIO-TEMPORAL QUALITY OF THE QUIAOIT RIVER WATERSHED IN ILOCOS NORTE, PHILIPPINES

Abstract

This study reports the spatio-temporal changes in water quality of the Quiaoit River watershed. Stream water samples were collected at eleven sampling stations weekly from July to December 2012 and were analyzed for five water quality parameters. Results showed distinct spatial and temporal variations of water quality measurements and spatial heterogeneity in terms of surface water pollution was attributed to anthropogenic factors. It was found out that water quality declined as the water moved downstream due to waste input from household and agricultural discharges. The mean dissolved oxygen concentrations are all below the standard minimum dissolved oxygen (6.0 mg/l) and minimum dissolved oxygen for fish spawning (7.0 mg/l). Likewise, mean nitrate-N concentrations within the test watershed ranged from 0.1 ppm to 3.4 ppm. Spatially, it was observed that nitrate-N concentration was highest in areas near agricultural areas. The above results suggest the need for proper management measures to restore the water quality of the Quaioit River. It also highlights the importance for objective ecological policy and decision-making process to ensure a healthy and sustainable aquatic ecosystem.