20 YEARS OF CHLORIDE REPORTING THROUGH A STATE-REGULATED PERMIT PROGRAM: WHAT WE'VE LEARNED ABOUT THE PAST AND FUTURE OF SALT-WATER ENCROACHMENT IN NORTH CAROLINA'S COASTAL PLAIN AQUIFER

Rising sea levels are expected to shift the salt-water transition zone of coastal aquifers further inland, putting already-stressed groundwater resources at greater risk of saltwater contamination. To protect groundwater users and plan for these changes, groundwater resource managers require reliable monitoring networks and models that can predict the rate and extent of inland saltwater migration. In North Carolina, groundwater chloride is routinely tested in the state-run monitoring well network and additional data is provided by groundwater users holding permits within the Central Coastal Plain Capacity Use Area (CCPCUA). This presentation will briefly discuss the history of the CCPCUA program, along with hydrologic and geologic factors contributing to the present location of the salt-water transition zone in the North Carolina Coastal Plain aquifer. We then show how water level and chloride data being collected through the CCPCUA permit program is being used to monitor trends in chloride concentrations and develop models that will support long-term water management plans that are responsive to projected changes in chloride resulting from sea-level rise.