The Florida Department of Health in Broward County recommended people don't swim south of the Pompano Pier.
Beach water collected in the area found high levels of bacteria, said health officials. Certain bacteria can cause gastroenteritis.
"The beach is still opened," said city spokeswoman Sandra King. "The bacteria level is just higher than normal but it's in the area that we like to advise people it's probably best not to swim right there."
Despite the warnings, many people swam there Friday.
"I didn't know anything at all," said Joe Bilotta.
New results after retesting will be available late Monday afternoon at posted at floridahealth.gov/healthy-environments/beach-water-quality/index.html.