Contra Costa County health officials on Monday announced harmful blue-green algae blooms have been reported in the Discovery Bay area and are recommending that boaters steer clear of them.
The blooms are buildups of cyanobacteria that can make people and pets sick if it gets in contact with them, Contra Costa Environmental Health officials said.
The state Water Resources Control Board reported several samples with dangerous levels of the toxin in the areas of Windward Bay, Clipper Bay and Discovery Bay Yacht Club in the community in East Contra Costa County.
County health officials have provided warning signs to the harbor master and Discovery Bay Community Services District and asks everyone to follow the instructions on the signs and stay out of the water.
Children and pets should stay on shore, and people should not drink or cook with water in the areas, or eat fish or shellfish caught in or near them, according to the county.