Ohio's Lake Erie Faces Mild-to-Moderate Algae Bloom Forecast

COLUMBUS, Ohio — The National Oceanic and Atmospheric Administration (NOAA) forecasts a mild-to-moderate harmful algal bloom (HAB) in western Lake Erie for summer 2026, measuring 3 on the HAB severity index with a potential range of 2 to 4. Unlike the above-average severity hinted in initial reports, this prediction aligns with average spring phosphorus loads from the Maumee River watershed, a key nutrient source fueling the cyanobacteria known as blue-green algae. The bloom is expected to become visible by early July, primarily in the western basin near Ohio's Lake Erie shoreline, including areas around Toledo and Sandusky.

HABs produce toxins that sicken humans and animals, foul beaches and kill fish, impacting Ohio's $1 billion recreational fishing industry and drinking water for 500,000 residents served by the Toledo water intake in Maumee Bay. In 2025, the bloom registered a mild severity index of 2.4, starting in early July in Maumee Bay and peaking in early August, below the prior year's 4.2. The 2024 bloom hit 6.6, moderately severe, while the target below 2.9 remains unmet most years despite progress in 2018, 2020, and 2023.

Ohio's agricultural heartland contributes heavily via phosphorus runoff from fertilizers during heavy rains, though this spring's average rainfall tempers the outlook. NOAA's late-July update will refine the forecast based on Maumee River nutrient data, with winds potentially shortening the bloom's typical July-to-October span. Local officials in Lucas and Ottawa counties advise avoiding green scum and checking Ohio EPA beach advisories to protect swimmers and boaters.