Prevent, Promote, and Protect your Health with the Lake County General Health District
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Painesville, OH 44077

Harmful Algal Blooms (HABs)

Harmful Algal Blooms (HABS)

What is a HAB?

  • Large growth of naturally occurring bacteria fed by nutrients in the water:  phosphorus and nitrogen
  • The nutrients of phosphorus and nitrogen come from agricultural runoff, sanitary sewer and combined sewer overflows, failing septic systems and application of fertilizers

What causes HAB?

Cyanobacteria, often called blue-green algae, are bacteria that are naturally found in Ohio lakes, ponds, and slow-moving streams. Although many species of algae do not produce toxins, some species of blue-green algae can cause HABs.

Under the right water conditions, which usually occur in the warmer months, the number of these blue-green algae can dramatically increase, or “bloom.” Scientists do not fully understand what cause the same species of algae to trigger toxin production during one bloom and not produce toxin during the next.

Some cyanobacterial blooms can look like foam, scum, or mats on the surface of fresh water lakes and ponds. The blooms can be blue, bright green, brown, or red and may look like paint floating on the water. Some blooms may not affect the appearance of the water.

Why is a HAB dangerous?

 The bacteria that form the HAB can release toxins that may be harmful to people and pets

  • Boaters and jet skiers are cautioned that water spray contact on skin or breathing/inhaling water droplets may cause health problems
  • Toxins may cause a skin rash, blisters or hives
  • Ingestion of the toxins can cause vomiting, diarrhea, dizziness, tingling, numbness, sore throat or headaches

What does a HAB look like?

  • Photos taken in Lake County on the Lake Erie shoreline in July of 2012

You can view more images of Ohio HABs by visiting: The Ohio EPA  website and clicking on the photo gallery of HABs.

What should you do if your pets are exposed to waters where a HAB is found?

  •  Rinse off after coming out of the water
  • In case of accidental ingestion contact a physician
  • In case of pet exposure contact your vet
  • If you or your pet becomes ill file a report with the state (links to forms below)

ODH HAB Human Illness Reporting Form
ODH HAB Animal Illness Reporting Form

If the HAB is no longer visible, is it safe to swim?

  • Toxins can still be present in the water even if the HAB cannot be seen
  • Look for the signs that warn about the presence of a HAB

Is it safe to eat vegetables that were watered with lake water this year?

Available research recommends that people no not eat leafy vegetables/greens (lettuce, spinach, cabbage, Brussel sprouts, chard, or other leafy vegetables/greens) irrigated with HAB-contaminated water. There is evidence with regard to cyanobacteria impacting root vegetables and no information concerning fruits.

For more information on HABs

Visit the Ohio EPA  and Ohio Department of Health websites
Harmful Algal Bloom – Ohio EPA
Harmful Algal Bloom – Ohio Dept. Health

Can I see where the HAB is on Lake Erie?