This is sewer overflow. It’s leaking raw sewage into your salt marsh. Overflows happen when there’s a backup or during heavy rains and floods. If you see something like this report it to the nearest sewer authority ASAP. They should respond, take action to contain it, and notify nearby homes and businesses. You can report to :
Charleston Water System: 843-727-6800
Mount Pleasant Waterworks: 843-884-9626
North Charleston Sewer District: 843-764-3072
Summerville CPW: 843-871-0810
Dorchester County Water and Sewer: 843-832-0075
Berkeley County Water and Sewer: 843-572-4400
Or contact us at CharlestonWaterkeeper.org/report and we’ll make sure it gets reported to the responsible party.