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Predicted bloom severity for 2024 as compared to previous years. Blooms with a severity index above 5 generally pose greater risk to drinking water and recreation in Lake Erie, but the impact of a bloom also depends on its location, toxicity, and duration. The largest blooms, 2011 and 2015, were 10 and 10.5, respectively.
Western Lake Erie is projected to experience a moderate harmful algal bloom (HAB) this summer, according to the first 2024 Lake Erie Harmful Algal Bloom Early Season Projection issued by NOAA’s National Centers for Coastal Ocean Science (NCCOS), with support from the National Center for Water Quality Research at Heidelberg University.
Models currently indicate a likely bloom severity between 4.5 and 7.5 (a moderate bloom is closer to a severity of 5). To date, precipitation and total bioavailable phosphorus (TBP) loads from the Maumee River in April were well above average, with the second highest April TBP loads since 2000. If precipitation for the rest of the spring remains near or below average, a moderate bloom is likely. If precipitation continues to be above average, a bloom with a severity closer to 7 is expected. The uncertainty for this forecast will continue to narrow as additional rain and river discharge data is collected over the next two months.
The severity of the western Lake Erie cyanobacterial bloom depends on input of total bioavailable phosphorus (TBP) from the Maumee River during the loading season (March – July). The NOAA forecast gives an estimate of potential bloom severity based on a combination of TBP measurements to date collected by Heidelberg University and forecasts of river discharge (by NOAA’s Ohio River Forecast Center) and phosphorus loads from now into July.
Projections of the bloom’s severity will be issued weekly through late June. On June 27, NOAA will issue the official Lake Erie HAB Seasonal Forecast in coordination with Ohio Sea Grant. Any bloom that develops will change with time and move with the wind, and NOAA will provide information on the presence and location of any bloom throughout the summer.
Click here to sign up for Lake Erie HAB updates via email.
True color image of Lake Erie on April 22, 2024 derived from the Copernicus Sentinel-3a satellite.