The Rock County Health Department is urging caution around ponds, lakes, and rivers. Rock County Environmental Health Director Rick Wietersen says conditions are favorable for the development of blue-green algae. Wietersen says the algae blooms often appear to be a floating scum layer resembling green, blue, or white paint or pea soup. Wietersen advises against swimming in areas of high algae concentration, avoid ingesting the water, and rinse off after coming into contact with the water. Symptoms of exposure can include skin or eye irritation, vomiting, and diarrhea. He adds pets and children are particularly vulnerable because of their size and natural tendency to want to play in the water.