ABSTRACT
Guam, an unincorporated U.S. territory in the western Pacific, is the largest (about 541 km2) and southernmost member of the Mariana Islands chain. It supports a local population of around 170,000 and attracts over 1.5 million tourists annually. Groundwater from the Northern Guam Lens Aquifer currently supplies local residents and over 1.5 million tourists with approximately 90% of their daily water needs. With 5000 marines and their dependents moving from Okinawa to Guam, and projected increase of local population and tourists, the groundwater quantity and quality need to be paid special attention. This chapter focuses on processing, visualization, and analysis of chloride data from drinking wells in the Northern Guam Lens Aquifers. According to the maximum contaminant level of chloride, an indicator for salinity at 250 mg/L recommended by U.S. Environmental Protection Agency, and based on analysis of the chloride data, the wells with water quality deficiency of salinity are located mostly in two clustered areas, the southeast and central west areas of the Northern Guam Lens Aquifer.
