Sullivans Island is a saltwater beach in Charleston County, South Carolina. Across 548 bacteria samples collected between 2021 and 2026 at nearby monitoring stations, it earns a Beach Safety Grade of F — Failing.
About 38% of samples at Sullivans Island exceeded the EPA Beach Action Value of 104 CFU/100 mL for Enterococcus — the threshold at which water managers typically post a swimming advisory. In practice that means the safe-swimming limit was frequently crossed here over the monitored period. Bacteria samples exceed the safe-swimming threshold a large share of the time — this beach flags advisories often.
The evidence behind this grade is deep for a beach page: 548 results from 11 monitoring stations, spanning 2021 to 2026. Enough sampling, from enough places, over enough seasons that one bad week can't drive the letter.
Sullivans Island was not under a swimming advisory in the most recent EPA snapshot. Conditions can change quickly after heavy rain or high runoff, so it's still worth checking the current advisory the day you go.