From http://hi.water.usgs.gov/recent/iao/

Background information about the Iao and Waihee aquifer areas

Since the introduction of pumping, groundwater levels have declined and the chloride concentrations of pumped water have risen above predevelopment levels at all of the well fields. In addition, the transition zone between freshwater and saltwater, which has been monitored at the Waiehu deep monitor well since 1985, has been moving upward during the period of record.