Nuisance flooding thresholds at the Charleston tide gauge

The governing gauge for the Charleston area is NOAA station 8665530, Charleston (Cooper River Entrance), NWS identifier CHTS1. Official coastal flood thresholds retrieved from the NOAA Tides & Currents metadata API on 2026-09-04, in feet above MLLW: National Weather Service thresholds — minor 9.77 ft, moderate 10.27 ft, major 10.77 ft. NOAA/NOS thresholds — minor 10.40 ft, moderate 11.33 ft, major 12.60 ft. These two sets are published side by side by NOAA and differ; the NWS values are the ones NWS Charleston issues coastal flood advisories and warnings against. NWS Charleston states that 'the vast majority of spring coastal flooding ranges in the minor flood stage or nuisance flooding' and references a major flood stage of 8.0 ft MLLW in its winter-flooding discussion, which does not reconcile with the 10.77 ft NWS major threshold in the NOAA metadata — report both and treat neither as settled without asking NWS Charleston directly. Practical use for a buyer: predicted tide heights above roughly 9.8 ft MLLW at this gauge are when Lowcountry street flooding starts being reported.