The Florida Department of Health Palm Beach County has issued a "No Swimming Advisory" for Dubois Park after recent sampling showed bacterial levels in the water to be in the poor range.
Officials say the causes of the elevated level are unknown but are generally associated with wildlife, heavy recreational usage, or runoff following heavy rains.
All other beaches from Boca Raton to Jupiter tested in the good range.
The area affected is Dubois Park's small lagoon, located just off the Jupiter Inlet.
Beach water quality for Palm Beach County and throughout the state can be found at www.flhealthpalmbeach.org and click on “beach water sampling”.