Some Brooklyn pet owners are being warned after Prospect Park Lake tested positive for an algae that could be harmful for pets.
Officials say not only is the water contaminated with a harmful blue-green algae bloom, but so is most of the water's shoreline.
The Department of Environmental Conservation says the whole lake tested positive for the bacteria.
The algae can cause throat irritation, vomiting, nausea and even difficulty breathing for pets.
The Parks Department is warning visitors and their pets to avoid any contact with algae and the water.