End-phase Rehabilitation Assessment of Boracay Island Using Microbial Parameters as Indicator of Water Quality

The tourism-dependent Boracay island continued to accommodate tourists reaching a peak of >2 million in 2017 after nearly breaching through the island’s ecological threshold in 2012. Anthropogenic pressures resulting in poor water quality and disturbance of wetlands forced the authorities to close the island and undergo rehabilitation from April 2018 to December 2019. Inland and offshore water quality were assessed during the final phase of rehabilitation, although the sewerage system at this time was not yet completed. Microbial parameters from water samples collected offshore, nearshore, and inland were analyzed for total coliform (TC), Escherichia coli and Enterococcus spp. using the IDEXX™ Colilert-18™ and Enterolert™ systems. The end-of-pipe drainage at the Dead Forest Drainage (DFD) yielded the highest concentration in microbial parameters recorded at >100,000 MPN/100 mL. Microbial loads were higher in the lagoons, wetlands, and the well used for drinking. In most inland sites, the permissible microbial concentrations were exceeded based on the Philippines’ Department of Environment and Natural Resources Administrative Order 2021-19. Despite the distance from the shore, TC, E. coli and Enterococcus spp. were detected even 3 km offshore with values ranging from 20 to 56,775 MPN/100mL, 20 to 11,199 MPN/100mL and 10 to 892 MPN/100mL respectively.