toxic down at korea state park exposure to humans can cause a rash, vomiting, diarrhea, cold and flu-like symptoms. the algae also poses a threat to pets. symptoms include vomiting, diarrhea, weakness, difficulty breathing and seizures, or death. that s why san mateo county s director of environmental health services have therefore, she is urging people to be mindful of the water and banks of the lagoon and creek through want everyone to avoid. swimming in it and allowing their pets in the water or even touching outing. it s it s not safe. here s another video. but the blue green algae looks like for she says these conditions that have been popping up around the bay area are most likely caused by the drought sign of bacteria and tend to grow in the warm summer months when the water is warmer and the water flow is slower. there isn t a lot slow. and the the water has been sitting there. it s been stagnant for quite a while. and so the algae is growing. pretty thick lai