The Swim Alert project tests bacteria levels at 20 popular sites so you know when and where it’s safe to swim. Samples are collected and analyzed every Wednesday, May through the end of October, to determine the amount of Enterococcus bacteria present. Testing results are published as soon as they are available so you can make informed choices about how to keep yourself and your family safe on the water.
All data is collected and generated under a DHEC-approved Quality Assurance Project Plan. Samples are analyzed by Charleston Waterkeeper staff at the College of Charleston’s Department of Geology and Environmental Geosciences’s Hydrochemistry Research Laboratory. Results that exceed South Carolina’s water quality standard of 104 CFU/100 mL are noted in red and indicate swimming may expose you to pathogens.
Charleston Waterkeeper uses the Swim Alert data to identify polluted waterways and advocate for clean-up projects and funding. Since 2013 Swim Alert has helped secure more than 1 million dollars in state and local funding for clean up work in local creeks and rivers like James Island and Ellis Creeks.
Data from past seasons are available here: Swim Alert Data.
Water quality monitoring programs like Swim Alert to use enterococci as fecal indicator bacteria because they are the best indicator of the risk to human health associated with swimming and other primary contact recreation activity in saltwater.
Two bacteria groups, coliforms and streptococci, are used as indicators of possible fecal contamination because they are commonly found in human and animal feces. Although generally not harmful themselves, they indicate that pathogenic (disease-causing) bacteria, viruses, and protozoans that live in human digestive systems may also be present. Therefore, their presence above certain levels suggests that swimming and other primary contact recreational activity might be a health risk.
Enterococci, a subgroup of the Streptococcus bacteria group, are known for their ability to survive in saltwater, like many pathogens. Enterococci are also generally more human-specific than other members of the streptococcus group.
SOURCE: Environmental Protection Agency, Volunteer Stream Monitoring: A Methods Manual, Section 5.11 Fecal Bacteria, EPA 841-B-97-003 (November 1997).