Lake Erie Harmful Algal Bloom FAQs

FAQs - Frequently Asked Questions about cyanobacteria blooms of Microcystis.

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NOAA's Lake Erie Harmful Algal Bloom Forecast System

What is the NOAA Harmful Algal Bloom Operational Forecast System (HAB-OFS)?

The official source of forecasts regarding harmful algal blooms of Karenia brevis (commonly known as red tide) in the Gulf of Mexico and Microcystis (cyanobacteria or blue-green algae) in Lake Erie. The routine HAB forecasts help members of the public make informed decisions when a bloom is temporarily affecting their area. The forecasts also aid people responsible for responding to bloom impacts.

How can I receive the HAB forecasts for Lake Erie?

View the most recent forecast here or subscribe to receive an email when the forecast is updated by signing up here.

What NOAA predictions are issued for Lake Erie HABs?
  • Lake Erie Harmful Algal Bloom Early Season Projections are issued weekly starting in mid-May. Early season projections estimate bloom severity based on measurements of phosphorus loading in the Maumee River. NOAA satellite operations are combined with historical records to determine weekly estimates for the remainder of the loading season. The seasonal projections provide coastal managers and drinking water facility operators a general sense of how “bad” the upcoming bloom season has the potential to be.
  • Lake Erie HAB Forecasts are issued twice-weekly throughout the bloom season (July - October). Each forecast provides current bloom location, and where it is forecast to transport or mix in the water column over 120 hours, as well as the predicted winds, currents, and water/temperature. View the most recent forecast here or subscribe to receive an email when the forecast is updated by signing up here.
  • At the end of each HAB season, NOAA provides a seasonal assessment. This is a retrospective analysis of the bloom.

Why does NOAA produce the Lake Erie HAB forecast?

The Lake Erie HAB Forecast provides information about the current location of the bloom and predicts its location over the next few days. This helps stakeholders target their response to minimize impacts. Through the use of this information:

  • Water treatment managers can chemically treat the water, or some plants use a temporary alternative source including a second intake or reservoir.
  • State agencies can guide toxin sampling efforts and close beaches where toxins exceed recreational swimming standards as well as issue warnings for pets.
  • Commercial and recreational boaters can plan activities that are outside of the bloom.


When are Lake Erie HAB forecasts issued?

Lake Erie HAB bulletins are issued beginning on the first Monday in July and cease when the Microcystis bloom dissipates. Microcystis blooms require a minimum water temperature of 65°F and so the typical bloom season extends from July to October.
During an active bloom, bulletins are released on Monday and Thursday. Since the bulletin relies on clear satellite imagery to produce accurate forecasts, the bulletin may be delayed by up to one day following overcast weather to allow for better imagery. Bulletins will also be delayed by up to one day following federal holidays.

What's included in the Lake Erie HAB forecasts?

A complete description of the bulletins is provided in the Lake Erie HAB Bulletin Guide. The following forecasts are included:

  • Transport forecast: Potential bloom transport is forecast based on satellite imagery that is incorporated, along with modeled surface currents, into a 2D particle trajectory model (Wynne T. T., et al., 2011).
  • Mixing nowcast/forecast: Vertical mixing of cyanobacterial cells through the water column reduces the visibility of the bloom at the surface. Forecasts of mixing and surface scum formation for three days following the bulletin date, are based on predicted winds. Nowcasts from the imagery date to the bulletin date are based on observed winds (Wynne T. T., Stumpf, Tomlinson, & Dyble, 2010).
  • Potential decline: The potential bloom decline is forecast when temperatures decrease below 15°C based on a study by Wynne et al. (2010).

What data are used in HAB monitoring and forecasting?

Forecast resoruces routinely included:

  • Ocean color satellite imagery from NASA and the European Space Agency (ESA).
  • Surface wind and currents observations from the Lake Erie Operational Forecast System (LEOFS).
  • Hydrodynamic modeling from the Great Lakes Environmental Research Laboratory (GLERL).
  • Microcystis sampling from state agencies and academic institutions.
  • National Weather Service (NWS) water temperature observations and forecasts.
See our Contributors & Data Providers page for more detail.

How far into the future can HABs be forecast?

The intensity and the extent of the area impacted by the bloom varies significantly from year to year. Before a bloom develops in Lake Erie, NOAA researchers, with their partners at Heidelberg University, provide experimental early season projections of the severity of the bloom. Lake Erie HAB forecasts provide predictions no more than three to four days in advance because it is not possible to reliably forecast bloom transport, mixing, or potential decline further into the future due to the variation of the environmental conditions the forecasts are based on.

About Cyanobacteria and Harmful Algal Blooms

What is a harmful algal bloom?

Algae is the term for simple plants that range from microscopic, single-celled organisms to large seaweeds. Harmful algal blooms are the rapid growth of microscopic algae that can negatively impact human and animal health. Read more from NOAA here

What are cyanobacteria?

Cyanobacteria (also known as blue-green algae) are bacteria that can photosynthesize (use sunlight to create food) like plants. Although they are single-celled, they can form large colonies that are visible to the naked eye. Some species of cyanobacteria can produce toxins, like the most common bloom forming genus in Lake Erie, Microcystis. Read more about cyanobacteria from NOAA's National Ocean Service here and the EPA here.

Why do harmful algal blooms occur?

To learn more about why harmful algal blooms occur and the research that is being done, visit the National Ocean Service Ocean Facts here. To read about the research being done to understand harmful algal blooms in Lake Erie, visit the Great Lakes Environmental Research Laboratory (GLERL) research page.

Harmful Algae/Cyanobacteria Impacts & Health Questions

What are the impacts of harmful algal blooms in Lake Erie?

The most common bloom forming genus of cyanobacteria, Microcystis sp.;, can form thick floating mats of green scum in Lake Erie and produces a toxin called microcystin.
Scums form after a period of calm winds, which allows buoyant Microcystis cells to accumulate at the surface. In bloom-level concentrations, the scums can clog the coolant systems of boat engines and close beaches. The toxin, microcystin, can pose a risk to drinking water, cause skin irritation, and negatively affect wildlife, pets, and livestock. Health officials conduct routine monitoring to ensure that public drinking water is safe. People should use caution when engaging in activities in or on the water during a Microcystis bloom. View a summary of health information here. For information regarding exposure to Microcystis and symptoms of microcystin, visit the Ohio Department of Health's HAB page. To seek medical advice concerning Microcystis, contact your health provider or find your local health department in Ohio or Michigan.

Can I boat and/or swim in Lake Erie during a harmful algal bloom?

  • You can still boat and recreate in Lake Erie waters, but be aware that HABs may be present.
  • What you can do:
    1. If you can, plan your trip by checking NOAA's HAB forecast before you go.
    2. Respect any waterbody closures announced by local public health authorities.
    3. Avoid activities in areas where the water is discolored by algae or scums are visible.
    4. Thoroughly wash yourself and pets after suspected contact with a HAB.
  • Find out more information:
    1. Ohio Environmental Protection Agency
    2. Michigan Department of Environmental Quality

Is it okay to eat fish caught in Lake Erie during a harmful algal bloom?

Commercial fish from local restaurants and markets is safe to eat because it is tested for HAB toxins before it is sold.

Additional Information Concerning Harmful Algal Blooms in Lake Erie

Additional Web Resources (click here to reveal a list)

To Obtain Health Information (click here to reveal a list)

Reference Literature (click here to reveal a list)

  • Wynne, T.T., Stumpf, R.P., Briggs, T.O. 2013. "Comparing MODIS and MERIS Spectral Shapes For Cyanobacterial Bloom Detection." International Journal of Remote Sensing.
  • Wynne, T.T., Stumpf, R.P. 2015. "Spatial and Temporal Patterns in the Seasonal Distribution of Toxic Cyanobacteria in Western Lake Erie from 2002-2014." Toxins. Volume 7. Pages 1649-1663.
  • Wynne, T. T., Stumpf, R. P., Tomlinson, M. C., Warner, R. A., Tester, P. A., Dyble, J. and Fahnenstiel, G. L. (2008) “Relating spectral shape to cyanobacterial blooms in the Laurentian Great Lakes”, International Journal of Remote Sensing, 29:12, 3665 — 3672
  • Wynne, T.T., Stumpf, R. P., Tomlinson, M. C., Schwab, D. J., Watabayashi, G. Y., Christensen, J. D. 2011. “Estimating Cyanobacterial Bloom Transport by Coupling Remotely Sensed Imagery and a Hydrodynamic Model.” Ecological Applications. Vol 21, 7, pp. 2709-2721.
  • Wynne, T.T., Stumpf, R. P., Tomlinson, M. C., Dyble, J. 2010. “Characterizing a Cyanobacterial Bloom in Western Lake Erie Using Satellite Imagery and Meteorological Data.” Limnological Oceanography. Vol. 55, 5, pp. 2025-2036.
  • Wynne, T.T., Stumpf, R. P., Tomlinson, M. C., Fahnenstiel, G. L., Dyble, J., Schwab, D. J., Joshi, S. J. 2013. “Evolution of a Cyanobacterial Bloom Forecast System in Western Lake Erie: Development and Initial Evaluation.” Journal of Great Lakes Research. Vol 39, pp. 90-99
  • Stumpf RP, Wynne TT, Baker DB, Fahnenstiel GL (2012) Interannual Variability of Cyanobacterial Blooms in Lake Erie. PLoS ONE 7(8): e42444. doi:10.1371/journal.pone.0042444