TOLEDO, Ohio — Approximately 360 square miles of Lake Erie were covered by algal bloom Tuesday, according to an update bulletin from the National Centers for Coastal Science and National Oceanic and Atmospheric Administration (NOAA).
The cyanobacteria bloom, also known as a harmful algal bloom (HAB), is continually monitored by these organizations throughout the summer, when it typically forms. According to scientists, the bloom has seen an increase since Aug. 26 and currently extends from Stony Point, Michigan past Huron, Ohio, in the lake's western basin. The highest concentrations have been detected in Maumee Bay and along the southern shore of Lake Erie towards Port Clinton.
Earlier this summer, local health officials issued a Recreational Public Health Advisory following high levels of cyanotoxins in the Maumee Bay. The advisory has since been lifted and swimming is once again permitted at Lake Erie Beach. A Bacteria Contamination Advisory does remain in affect at Maumee Bay State Park.
NOAA officials said that while detected toxins are below the recreational limit, toxins can still be highly concentrated in scums; if you see scum, you are advised to keep yourself and your pets out of the water. Cyanobacteria scum appears as a bright green layer on top of affected water. It is pictured below:
Algal bloom forecast
The scum risk is forecasted to increase from "Very Low" to "Medium" in western Lake Erie between Tuesday and Wednesday, before decreasing to "Very Low" and "Low" through Thursday. On Friday, it will increase again to "Medium", according to an NOAA bulletin.
To see an hour-by-hour breakdown of the HAB forecast over a six-day period, click here.
The harmful algae bloom typically peaks in August and September during late summer and early autumn. Earlier this year, experts predicted a slightly smaller-than-average algae bloom this year, measured quantitatively in terms of a severity index around 3. On July 27, however, scientists with the NOAA updated their forecast to predict a bloom severity of 4.5 at minimum, with a maximum of 5.5.
The greater the severity index, the larger the bloom. Some years, such as 2015, 2017 and 2019 delivered large outbreaks of harmful algae with a severity index near or over 10.
Though this year's bloom is expected to be smaller than usual, it will still pose hazardous health impacts, especially in the western basin.
It will not be clear until the end of the season where the 2023 HAB fell on the severity index.
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