The state has issued a swimming advisory for all Horry County beaches following subtropical storm Alberto.
The Department of Health and Environmental Control issued the warning on Tuesday evening.
"Due to the impact of the amount of rainfall associated with Alberto, all beaches in Horry County have been placed under a swimming advisory," the announcement reads.
Water sampling showed bacteria levels exceeding safe swimming standards at all but three locations. The cause of the high number is due to excessive rainfall in the last few days, according to DHEC.
Swimming is not advised until bacteria levels return to normal.
The department states it is safe to wade, collect shells and fish while under the advisory. People with open cuts or other wounds should avoid contact with the water.
DHEC officials say it could take several days before bacteria levels return to acceptable levels.
"The absence of signs at any location during the next several days is not an indication that bacteria levels have returned to normal.," the announcement reads. "This is an unusually widespread event that could take several days to clear. "
Several people who were swimming in the ocean on Tuesday evening said they were unaware of the advisory.
On Wednesday, DHEC Spokeswoman Adrianna Bradley said a recent sewer line break in Myrtle Beach might have been a "minimal local contributor" to the advisory, but it would not have influenced other areas of the county. She again cited rainfall and storm water runoff as the factors for the high bacteria levels.