When the Shoreline Moves Toward the Well: Saltwater, Erosion, and Island Drinking Water

Takeaway: On a small island, a well can turn salty not just when the sea rises, but when the shore shrinks and the rain stops refilling the ground.Small islands often depend on a thin, hidden store of freshwater underfoot. As climate change reshapes coasts, that underground water can be squeezed by the sea, by storms, by drier weather, and by erosion that physically moves the shoreline closer to wells. This episode visits Lennox Island in Atlantic Canada, where researchers worked with the Lennox Island Mi'kmaq First Nation to ask a practical question: which climate pressures most threaten the island aquifer that supplies drinking water?We unpack how freshwater and saltwater share space underground, why a confining layer can protect an aquifer from storm flooding, and why coastal erosion plus reduced recharge can be a powerful one-two punch. The study used field measurements, electrical resistivity surveys, and an integrated surface-subsurface computer model to test sea-level rise, storm surge, changing recharge, erosion, and combined impacts. The surprising result: storm surges had little effect on the deeper pumped aquifer in this setting, while reduced recharge and erosion pushed saltwater farthest inland, and together could move the saltwater wedge into the wellfield.Citation: Stanic, S., LeRoux, N. K., Paldor, A., Mohammed, A. A., Michael, H. A., & Kurylyk, B. L. (2024). Saltwater intrusion into a confined island aquifer driven by erosion, changing recharge, sea-level rise, and coastal flooding. Water Resources Research, 60, e2023WR036394. https://doi.org/10.1029/2023WR036394Disclosure: This Waterlines episode package is written for production with AI-generated host voices.