MAYVILLE - As the boating and swimming season ends in Chautauqua County, the Health Department reminds everyone to be cautious of continued blue-green algae in area waters. These algae, technically known as cyanobacteria, are microscopic organisms that are naturally present in lakes and streams. They usually are present in low numbers but blue-green algae can become very abundant in warm, shallow, undisturbed surface water that receives a lot of sunlight. When this occurs, they can form blooms that discolor the water or produce floating rafts or scum on the surface of the water. These blooms may appear thick like pea soup, like green paint, or like grass clippings on the water.