Assessment of the quality of groundwater wells in the island Municipality of Panglao, Bohol, Philippines

Abstract

The study was conducted in the Municipality of Panglao, Bohol, Philippines to investigate water quality in 81 wells using parameters such as pH, dissolved oxygen (DO), electrical conductivity (EC), total dissolved solids (TDS), sodium chloride (NaCl), temperature, and nitrate-N. Spatial variation is analyzed through ArcGIS 10.6 and regression analyses.

Results showed that about 40% of the study area’s nitrate concentration exceeded the maximum contaminant level (MCL) of 10mg L^-1 as set by US EPA under the Safe Drinking Water Act. The water quality was poor mostly in barangays with high-density built-up and along the foreshore. On the average, pH was 7.44, DO was 4.27mg L^-1, EC was 3954.82µS, TDS was 3480.60mg L^-1, NaCl was 4377.50ppm, temperature was 29.36ºC and nitrate was 11.05mg L^-1.

The multiple regression analysis showed that nitrate is significantly predicted by well to shoreline distance and 2D IDW. The T-test results indicated that the level nitrate concentration differ significantly between the types of well which was found to be higher in shallow wells and lower in deep wells.

Based on the overall results, the following recommendations were drawn for the Municipality of Panglao to implement: a) install a wastewater treatment facility to address the unfavorable presence of nitrate and other contaminants in the groundwater, and b) enact relevant ordinances to stop the rising influences of nitrate concentration and other water contaminants of its groundwater which are detrimental both to its growing population and to the environment.