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​What To Do if You Suspect a HAB

If a HAB is suspected or confirmed to be occurring in a body of water, it is strongly recommended for people and pets to follow safe water recreation practices to limit exposure:

  • Wash your hands after contact with untreated water
  • Shower or bathe people and pets immediately after participating in water-based recreation activities
  • Avoid swallowing and inhaling untreated water during recreational activities
  • Avoid contact with water that has foam, scum, or discoloration
  • Seek and follow any waterbody advisories or closures

If you or your pet becomes ill or shows signs of poisoning after being in or around a waterbody with a suspected or confirmed HAB, call your doctor, veterinarian, or the poison control center:  Poison Control Center 800-222-1222; Animal Poison Control Center 888-426-4435.

If you have any health-related questions about HABs, please contact the Division of Environmental Health Epidemiology at the Pennsylvania Department of Health at  For other inquiries about HABs or to report a suspected HAB, contact the Pennsylvania HABs Task Force at

Be on the lookout for HABs watch, advisory, and warning  signage.

HABs Watch Sign HABs Advisory Sign HABs Warning Sign

The Pennsylvania HABs Task Force uses the following human primary contact recreational use thresholds for four cyanotoxins and for cyanobacterial colony density.

Response level
colony density
​Advisory (Yellow)
​8.0 *
​8 †
​15 *
​0.8 †
​Avoid Contact (Red)
​20 †
​300 †
​20 †
​3.0 †

* recommended values from US EPA 2019
thresholds from the State of Ohio Harmful Algal Bloom Response Strategy for Recreational Waters (see Table 2)

The United States Environmental Protection Agency (US EPA) has also issued the following 10-day drinking water health advisories for two cyanotoxins.

​Bottle-fed infants and pre-school children
​School-age children and adults

* recommended values from US EPA

Here are some additional resources on what you can do if you encounter a suspected or confirmed HAB.

Recreational use resources

Drinking water resources