Early forecast predicts moderate algal bloom

SANDUSKY — Scientists have issued an early forecast for the 2026 harmful algal bloom in Lake Erie, believing that it appears it's likely to be moderate. The forecast from the National Centers for Coastal Ocean Science, a branch of the National Oceanic and Atmospheric Administration, indicates that based on early indications, a bloom with a severity of 2 to 5.5, on a scale of 1 to 10, appears to be likely this summer. The blue-green bloom, produced by the Microcystis organism, has become an annual problem in Lake Erie, as it produces toxins and a scum on the surface of the water that humans and pets are advised to avoid. The scientists said that their forecast is for a wide range of possible severity but said they expect to be able to provide a more accurate forecast when a comprehensive seasonal forecast is issued on June 25. "The range in forecasted severity reflects the uncertainty in forecasting precipitation from now through July," they said. "If high precipitation and associated loads continue, there is a small chance of a bloom up to 5.5, similar to 2010. If precipitation stops and is less than normal through the rest of the spring and early summer, the bloom could be more mild similar to 2020." The forecast is based largely on the amount of bioavailable phosphorus put into Lake Erie by the Maumee River during the loading season, March 1 through July 31. Once a bloom does develop, it will be tracked by satellite, and the information about where it has formed will be regularly shared with the public, the forecast said. Last year's algal bloom was relatively small: 2.4 on a scale of 1-10. The annual official forecast, delivered as usual at Stone Laboratory at Put-in-Bay, had predicted a 3 with a possible range of 2-4, so the results were in line with the prediction. Last year's bloom began in early July in far western Maumee Bay and ended in late October, although the end was not announced at the time because the government shutdown interrupted the administration's algal bloom news bulletins. Last year's full bloom got off to a late start. While past blooms were fully developed in July, the 2025 bloom did not get fully established until early August.