Groundwater is an essential source of freshwater. However, this natural resource exhibits high vulnerability to contamination due to human activities and natural phenomena. Over extraction of groundwater and sea level rise have hastened seawater intrusion in aquifers that lie along the coasts. This has led to the accelerated deterioration of groundwater quality in coastal aquifers. Thus, there is an urgent need to develop tools to monitor groundwater resources. In this study, a framework of selecting priority areas for monitoring was applied to Mandaue City, Philippines. The monitoring areas were selected based on their vulnerability to seawater intrusion using the GALDIT-index. A collection of 77 initial public sites were investigated as potential locations of monitoring wells. The resulting network determined 45 priority areas located across the study area wherein monitoring wells should be located for the long-term observation of groundwater quality. These sites are composed of 28 from the initially investigated locations and 17 proposed sites which were determined to satisfy the required number of wells lacking in certain areas. The results of this study are intended to aid decision makers in creating groundwater management plans.