A novel water pollution index for domestic water quality assessment in acid mine drainage-impacted mining areas

A legacy copper mine in Sto. Niño, Barangay Ambassador, Tublay, Benguet, Philippines, has generating acid mine drainage (AMD), posing environmental and social challenges affecting access to clean water for domestic use in mine-impacted areas. With multiple water sources in the area, classification and prioritization of use, as well as treatment intervention are necessary. This study presents and develops a novel water pollution index (WPI-AMD) designed to assess domestic water quality in AMD-impacted mining areas. The WPI-AMD utilizes a multi-criteria decision-making (MCDM) tool called the weighted aggregated sum product assessment (WASPAS) approach, integrating both additive and multiplicative functions to overcome shortcomings of existing water quality and pollution indices (WQPI). WPI-AMD includes careful selection, categorization, weighting, normalization, calibration, and aggregation of relevant geochemical parameters. Sampling was conducted in the legacy mine to determine the geochemistry of the identified water sources. The results show that WPI-AMD effectively evaluates AMD-impacted bodies for domestic use, providing more accurate assessment than other WQPI in terms of eclipsing percentage, agreement with expert judgement, and classification accuracy. Thus, WPI-AMD is a promising tool for water resource management in mining-affected areas, facilitating the classification of water bodies according to their suitability for domestic use and in identifying critically polluted water bodies that require intervention. The ability of WPI-AMD to integrate multiple geochemical parameters into a single, easily interpretable score makes it particularly useful for community members, policymakers, and environmental managers in addressing water quality issues in AMD-impacted regions.