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Harmful Algal Blooms (HABs)

Harmful Algae Bloom Map

HAB's Hotline: 1-888-238-6154

Photo by Centers for Disease Control

Algae (AL-gee) are naturally-occurring microscopic organisms that are found in fresh and salt waters of Virginia and around the world.  Many are beneficial because they are major producers of oxygen and food for many of the animals that live in these waters.

Most algae do not harm people, wildlife, or the environment.  But some types of algae in Virginia can be dangerous.  Algae species in fresh and salt water may multiply rapidly when environmental conditions are favorable for their development.  The great number of algal cells in the water results in what is called an algal bloom.

A bloom often (but not always) results in a color change in the water. Algal blooms can be any color, but the most common ones are red or brown and are known as either “red” or “brown” tides.  Most algal blooms are not harmful but some do affect fish and humans, as well as other animals like birds and marine mammals. These are known as Harmful Algal Blooms (HABs).

The Virginia Department of Health is working in cooperation with the Virginia Department of Environmental Quality, Old Dominion University, the Virginia Institute of Marine Science at the College of William and Mary, and the U.S. Centers for Disease Control to monitor Virginia's waters for harmful algae and to prevent illness that may be caused by these organisms.

Different Types of Harmful Algae:

Cyanobacteria (also known as Blue-Green Algae)

Pfiesteria (pronounced “fist-eerie-a”)

Other Harmful Algae

How do I report an Algal Bloom or Fish Kill?

  • If you see a red or brown tide, water that has an odd color, or a fish kill call:
    The Department of Environmental Quality: (757) 518-2000
  • If you see fish with lesions call:
    The Virginia Institute of Marine Science: (804) 684-7000

If you are concerned that you have been exposed to a HAB, please see your doctor or call your local health department. Telling your doctor about contact with water may help him/her treat the illness properly.

  • If you have health concerns, please call:
    Virginia Department of Health, HABs Hotline: (888) 238-6154



Last Updated: 08-07-2014

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