All of Mississippi's Gulf Coast beaches have been closed to swimmers due to an algae bloom connected to the opening of the Bonnet Carre Spillway.
Pascagoula Beach was the last to restrict swimming, after tests came back positive from testing sites on the west and east sides of the beach, according to a report by the Mississippi Department of Environmental Quality.
Louisiana residents looking for some fun in the sun often travel to the bordering state to visit the beaches.
The beaches themselves remain open, but swimming in the water or eating fish caught off any of the closed beaches could make people sick.
The problem is a harmful algae bloom, which forms in waters that have abundant nutrients. The HAB, which looks like foam or scum on the surface of the water, produces toxins that have been linked to a variety of illnesses in people and animals.
Lake Pontchartrain is also facing the algae bloom, with Northshore beaches closed to swimmers.
The HAB is thought to have been caused by the opening of the Bonnet Carre Spillway, which has dumped freshwater into the ocean.
The Army Corps of Engineers is expected to begin closing the spillway sometime in July.