Harmful algal blooms thrive in warm, slow-moving water and can pose health risks to people and pets. Klamath County Public Health says people should avoid water that smells bad, looks discolored or has a foam or scum on the surface. Valaree Lane with Klamath County Public Health says moving bodies of water are less likely to develop blooms. Lane said even when a harmful bloom is present in Klamath Lake, some areas can still be used for recreation. Information about affect waterways found can be found on the Oregon Health Authority website .