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Energy and Environment Cabinet

Division of Water
Harmful Algal Blooms

​Blue-green algae occur naturally in the environment and are a vital part of the ecosystem. Harmful algal blooms arise when there are excess nutrients (phosphorus and nitrogen), sunny conditions, warm temperatures and low-flow or low-water conditions. The more typical green algae, which do not produce toxins, come in many forms and may appear as underwater moss or stringy mats.

Blue-green algae, on the other hand, appear as slicks of opaque, bright-green paint, but closer inspection often reveals the grainy, sawdust-like appearance of individual colonies or bacteria. The color of the algae may also appear red or brown.


HAB Advisories:
  • Boltz Lake (Grant Co.): Recreational Public Health Watch (updated 4/17/2017) - 
    Algal toxins present at levels that may affect sensitive populations. Swimming and wading are not recommended for children, pregnant or nursing women, those with certain medical conditions, and pets.
    Click here to access the HAB map viewer.  HAB warnings are identified on the map viewer by a Red diamond and HAB watches are identifed by a Orange diamond. (Note:  this viewer will only work when using one of these web browsers: Google Chrome, Firefox or Safari.)

    Public lakes or rivers identified with a HAB advisory remain open to the public. lakes or rivers identified with an HAB advisory remaining open to the public.

    To report a HAB please contact the KY Division of Water at 502-564-3410.



Recommended Precautions:

The following guidelines are recommended to avoid exposure to HABs:

  • Individuals should avoid direct contact with affected water that has unusual color or where blue-green algae have been identified, including swimming, wading, paddling, diving, and water skiing.
  • People who are prone to respiratory allergies or asthma should avoid areas with HABs. Children may be particularly sensitive.
  • If you come into contact with water containing blue-green algae, wash off with clean, fresh water. In some cases, skin irritation will appear after prolonged exposure. If symptoms persist, consult your local health care provider.
  • Fish fillets (not organs) may be consumed after the fillets have been rinsed in clean, non-lake water.
  • Prevent pets and livestock from coming into contact with water where HABs are apparent.

If you are concerned that you have symptoms that are a result of exposure to HABs please see your doctor and call your local health department.

Additional Information:

HABs can develop over a short period of time. Visitors are still advised to be aware of the potential for a harmful algal bloom and follow the recommended precautions.

To read more about HABs, click on the links below:

Harmful Algal Bloom Photos