Water Resources Research Act Program

Principal Investigators:

Abstract: Guam, an unincorporated U.S. territory in the western Pacific, is the largest (about 541.3 km2) and southernmost member of the Mariana Island chain. It currently supports a local population of around 170,000 and receives over 1.5 million tourists annually. About 5000 marines will be relocated to Guam from Okinawa in the next few years. With the marines and their dependents moving to Guam, and the importation of foreign labor to assist with the buildup activities and infrastructure needs of the military, the island’s population is expected to soar in the next few years. Groundwater from a karst limestone aquifer in the northern Guam currently supplies local residents and tourists alike with approximately 90% of their daily water needs. While estimates of the aquifer’s sustainable water resources remain adequate for the current population, there is serious concern that the projected population increase will severely compromise the island’s drinking water supplies and have an unprecedented impact on water quality and quantity. The high porosity and rapid recharge characteristics of the northern Guam len aquifer make it especially susceptible to contamination from urban runoff, chemical spills, effluents from septic tanks and sewage overflows. Guam Waterworks Authority (GWA) is the custodian of Guam’s public water supply and is responsible for ensuring that it meets all appropriate standards as mandated under the Safe Drinking Water Act and Clean Water Act. To this end, GWA regularly evaluates the physical, chemical and biological integrity of the island’s drinking water in accordance with US EPA requirements. While the agency has amassed a considerable amount of monitoring data over the years, only values that approach or exceed the water quality standards are paid attention. The rest, which account for well over 99% of all monitoring data collected so far, falls well below critical thresholds of concern and is of little immediate interest or attention. As a consequence, these data are simply stored on file for reference purposes only when in fact they could and should be used to identify subtle changes in contaminant abundances and distributions within the aquifer or changes for a long term basis. Since around 5000 marines will be relocated to Guam, particularly the Finegayan Area in the next few years, it’s very important to evaluate whether relocation of the marines and their dependents, and related activities will affect the quantity and quality of the water resources, especially groundwater resources. Based on this concern, the project will focus on inventory of hydrological features and hydrological analysis in the Finegayan Area. The hydrological features in the Finegayan Area will be collected, processed and organized into a geospatial database so that the data can be utilized for further analyses and applications in the future. Hydrological features will be evaluated on whether they will have imposed impacts on water quantity and quality of groundwater resources in the Finegayan Area.