The severity of the western Lake Erie cyanobacterial harmful algal bloom (cyanoHAB) depends on input of total bioavailable phosphorus (TBP) from the Maumee River during the loading season, from March through July. Models currently indicate a likely bloom severity between 2 and 5.5.
Throughout the spring, conditions have been relatively wet with a particularly high precipitation and associated river TBP input event in early April. The uncertainty for the forecast should continue to narrow as additional river discharge and phosphorus loads are measured over the next two months
Projections of the bloom’s severity will be issued weekly through mid-June. On June 25, 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. NOAA will provide information on the presence and location of any bloom that develops throughout the summer.
The full satellite time series for Lake Erie, dating back to 2009, was reprocessed in 2025 with updated satellite calibrations, improved algorithms, and additional data, generating a more complete, consistent, and continuous data set for HAB monitoring in the lake. You can find more information about the updated time series here.
This work is authorized under the Harmful Algal Bloom and Hypoxia Research and Control Act (33 U.S.C. §§ 4001 et seq.).
