The most congested beaches in South Carolina and across the nation tend to be the dirtiest to swim, a new study concluded, echoing earlier reports.
And the worst in the state might be the Withers Swash stretch of Myrtle Beach, where a creek flows into the ocean amid the heavily trafficked "Golden Mile" of high-rise hotels.
The state's beaches are cleaner than beaches overall and cleaner than surrounding states, according to the study released Tuesday by the nonprofits Environment America Research & Policy Center and Frontier Group.
The study used tests for fecal bacteria — human and animal waste — compiled by the S.C. Department of Health and Environmental Control and the Environmental Protection Agency.
The nonprofits are among a number of advocates who conduct surveys and comb reports to produce a series of findings to push for environmental cleanups.
In South Carolina, 55 of 129 beach sites tested unsafe at least one day in 2018, according to the study.
"A sampling site at Withers Swash in Horry County was potentially unsafe for 32 days, more than any other site in the state," the report says. Other beach counties in the state tested unsafe only 1 or 2 percent of the time, the report noted.
In comparison, 127 of 213 beach sites in North Carolina were considered unsafe in at least one day of testing. In Georgia, 13 of 26 were considered unsafe. Nationally, more than half of 2,627 sites tested were considered unsafe for at least a day.
The study did not specify seasons or detail days tested. Rain runoff can carry pollution, and most beach closings in South Carolina tend to be short term after rainstorms leak fecal waste from yards or streets into the water.
DHEC regularly monitors 123 of the 129 sites (the others are monitored by local groups) and issues temporary swimming advisories, or cautions, when fecal levels get unsafe. No temporary advisories were out on Tuesday.
Long-term advisories were in place for 13 sites — many of them along swashes, or outflowing channels of water, and all of them in the Grand Stand stretch, including Myrtle Beach's Withers Swash.
The monitoring sites are updated in real time on the department's Beach Guide, gis.dhec.sc.gov/beachaccess.
"Like the EPA, DHEC advises beachgoers to avoid water coming from storm drain pipes and discharge pipes, as well as swashes, which can have elevated levels of bacteria," said DHEC spokeswoman Laura Renwick. "The department also recommends that people with open wounds or compromised immune systems avoid contact with natural water bodies in most cases."
The department commonly issues temporary advisories after rains, she said. Those advisories usually last only one or two days until the pollution levels settle to normal standards. DHEC also encourages people to reduce runoff pollution with measures such as by cleaning up pet waste, not dumping materials down storm drains and using car washes.
The fecal pollution can crop up from other sources.
Hundreds, if not thousands, of beachfront septic tanks are buried in the dunes up and down the coast, the leach fields underground sometimes draining the effluent toward the ocean. They are a legacy of the camp and beach cottage days of the coast, a make-do time when people hauled old cabooses the beach to use as cabins.
The Natural Resources Defense Council in a 2018 State of the Beaches report cited leaky septic systems as a leading cause of beach water contamination.
Septic systems are underground set-ups that hold sewage in an anaerobic, or oxygen-free, tank so material can sink and decompose, while the somewhat cleaned-up effluent seeps to an adjacent "septic field," or leach field.