Lake Erie harmful algae bloom threatens drinking water supplies

What happened? What caused it? What can you do? Your questions answered.

Satellite image of 2011 bloom, the worst bloom in recent years, which impacted over half of the lake shore Photo credit: MERIS/ESA, processed by NOAA/NOS/NCCOS
Satellite image of 2011 bloom, the worst bloom in recent years, which impacted over half of the lake shore Photo credit: MERIS/ESA, processed by NOAA/NOS/NCCOS

Lake Erie is no stranger to algae blooms, including blooms of blue-green algae (cyanobacteria), which can produce toxins that pose health threats.  Blue-green algae are toxin producers, also known as Harmful Algae Blooms (HABs).  This past weekend, the city of Toledo, Ohio and a number of municipalities and townships in southeast Michigan lost their normal source of drinking water – Lake Erie – due to Microcystin, the toxin produced by Microcystis that was detected in water samples. Microcystin is the most common HAB species in the Great Lakes.

The Associated Press reported that Toledo residents were warned not to drink or bathe in city water early on Saturday, August 2, after tests at one treatment plant showed readings for microcystin above the standard for consumption.  Michigan households and businesses served by the Toledo municipal water supply were under the same ban. On Monday, August 4, the Mayor of Toledo lifted the ban after tests on the water passed EPA standards.

Harmful Algae Bloom infographic courtesy of Michigan Sea Grant.

Graphic: Find the original, downloadable graphic on Michigan Sea Grant's Flickr page. You may use the graphic for educational, non-commercial purposes. Credit "Michigan Sea Grant."

For those dealing with Harmful Algae Blooms, or water supplies contaminated by toxins from HABs, many critical questions come immediately to mind.  Some of the most common Frequently Asked Questions and their answers follow:

  • Can I drink the water? 
    • NO - don’t drink untreated surface water, whether or not blooms are present.  Remember that BOILING THE WATER WILL NOT REMOVE THE TOXINS and PAY ATTENTION TO WATER ADVISORIES.
  • Can I cook with the water? 
    • NO - do NOT cook in contaminated water.  Again, boiling will NOT remove the toxins.
  • Can I bathe or swim in the water? 
    • NO - avoid contact with contaminated water.  Even at low levels some people and animals with sensitive skin may have allergic reactions to algal toxins. The more concentrated the algae and the longer people remain in the water, the more severe the symptoms.
  • Can I use the water for pets and livestock? 
    • NO - pets and livestock should not drink water unsuitable for human consumption.
  • Can I use the water on my lawn and plants? 
    • If an advisory or ban has been issued, it is best to avoid contact with contaminated water.
  • Can I eat fish caught from waters where HABs occur?
    • You should not eat fish as they can concentrate toxins. The liver and gut of fish are also likely to be toxic. Other parts of the fish may be eaten but they must be cleaned with uncontaminated water. If you are in an area where HABs occur, it is also recommended to avoid eating shellfish from those waters as they can also concentrate toxins.
  • What symptoms might I experience if I’ve been in contact with the water?
    • Skin rash
    • Flu-like symptoms
    • Tingling or numbness of the lips and mouth within ½ to 3 hours after exposure.
    • Severe exposure: motor weakness, incoordination, respiratory or muscular paralysis.
  • What if I think I’ve been exposed to algal toxins
    • Rinse yourself and/or your pet off after swimming in any ponds, lakes or streams.
    • Get medical treatment right away if you think you, your pet, or your livestock might have been poisoned by algal toxins.
    • Remove people from exposure.
  • Who do I contact if I have further questions or concerns about the water or exposure to the water?

Michigan State University Extension will be featuring additional information on Great Lakes HABs on its website this month.  Michigan Sea Grant can provide additional information on Great Lakes HABs and other topics of interest, and Sea Grant Extension staff work with communities on planning and risk reduction strategies on a range of topics in addition to HABs.  For more information specifically about HABs and other Great Lakes issues relating to human health, visit the Center of Excellence for Great Lakes and Human Health, which also provides a weekly Lake Erie HAB forecast, and is part of the Great Lakes Environmental Research Laboratory.

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