HONOLULU - The U.S. Environmental Protection Agency last week released a final report, "Lahaina Groundwater Tracer Study," with results from a University of Hawaii investigation of the fate of effluent injected at Maui County's Lahaina Wastewater Reclamation Facility near the Kaanapali coast.
The report is posted online at www.epa.gov/region9/water/groundwater/uic-permits.html#lahaina.
Funded by the U.S. EPA, U.S. Army Corps of Engineers and the Hawaii Department of Health, the University of Hawaii has been studying the effluent flow from the Honokowai plant's injection wells to the near-shore ocean water since July 2011.
The results of the study conclusively demonstrate that a hydrogeologic connection exists between two of the facility's injection wells and the nearby coastal waters of West Maui.
A tracer dye added to the facility's Injection Wells 3 and 4 took approximately three months to first emerge from submarine seeps near the shore along North Kaanapali Beach.
The seeps are located roughly a half-mile to the southwest of the facility.
Results suggest an average travel time from Injection Wells 3 and 4 to the seeps in excess of one year.
The study also estimated that 64 percent of the treated wastewater injected into wells 3 and 4 discharges within two discrete near-shore zones where the submarine seeps are located.
Additional key results detailed in the final report include the temperature, salinity, pH, nutrient concentrations and discharge rate of the monitored submarine discharges.
EPA is carefully reviewing the final study results and is consulting with the Hawaii DOH on appropriate next steps in light of the research findings.