Preventing Harmful Algal Bloom-Related Illness

There is no way to tell if a blue-green algae bloom is toxic or not just by looking at it, so if you see a bloom in a lake, you and your pets should avoid contact with the water until it goes away. Always remember, “When in doubt, stay out!”

• You can prevent harmful algal bloom-related illness by:
  • Avoiding contact with water where a harmful algal bloom may be occurring
  • Using caution when consuming fish caught from waters where a bloom is occurring
  • Using caution when taking algal supplements

Minimizing Your Risk

Avoid contact with water where a harmful algal bloom may be occurring

• Do not swim, water ski, or boat in areas where the water is discolored or where you see foam, scum, or mats of algae on the water.
• If you think you swam in water with a harmful algal bloom, rinse off with fresh water immediately.
• Do not irrigate lawns or gardens with lake or pond water that looks scummy or smells bad.
• If odors cause discomfort, leave the area if possible.

Use caution when fishing and consuming fish caught from waters where a bloom may be occurring

• Toxins from algae can accumulate in the entrails (guts) of fish and occasionally in the muscle (fillet) of fish. Levels in fish depend upon the severity of the bloom in the area where the fish are caught. There is some uncertainty about the levels of algal toxins that can accumulate in filets, so to be consistent with other MDH guidance related to known or potential harmful algal blooms that recommend not contacting surface waters with blooms, anglers may want to wait a week or two after algal blooms are over before fishing and eating fish from waters where a bloom is occurring.

Use caution when taking algal supplements

• Use caution and consult your doctor about the risks when considering whether to take algae supplements.

Do you suspect you are experiencing adverse health effects from a harmful algal bloom? Visit reporting suspected foodborne/waterborne illnesses.