NCCOS: Western Lake Erie Harmful Algal Bloom Covers About 480 Square Miles08/25/2026The algal bloom in western Lake Erie now measures about 480 square miles in area, according to the National Centers for Coastal Ocean Science. That’s an increase in area since Friday, with the cyanobacteria bloom present from Stony Point, Michigan to Marblehead, Ohio and toward the islands. NCCOS says toxins have been detected below the recreational limit, but to keep yourself and your pets out of the water if you see algae scum. Click here to see the NCCOS' full algal bloom forecast.