Forecasts Predict Smaller Lake Erie Algal Bloom for 2020


  • NOAA
COLUMBUS, Ohio — Forecasters continue to predict that the annual harmful algal bloom on Lake Erie will be smaller this year than it was in 2019.

The latest weekly Early Season Projection from National Oceanic and Atmospheric Association (NOAA) estimates, on a scale of 1 to 10, a bloom with a severity between 3 and 5.

Laura Johnson is director of the National Center for Water Quality Research at Heidelberg University, which releases the projection. She says that's a smaller bloom than others in recent years.

"It's probably going to affect the areas that are affected no matter what. So, that's going to be through that Maumee Bay area," Johnson says. "But we don't expect it will have nearly the extent as what we saw in 2015, when it was taking up the whole Western Basin."

The bloom in 2019 had a severity index of 7.3 and reached a maximum size of about 700 square miles; in 2018, the severity index was 3.6 and in 2017, 8.0.

Harmful algal blooms are comprised of blue-green algae that can produce dangerous toxins that pose a risk to public health, as well as the economies of lake communities. Johnson notes the prediction does not reveal much about the toxicity of the bloom.

Researchers examine phosphorus loads from the Maumee River to determine the size and severity of the algal bloom. Johnson says with drier ground and fewer rainfall events during the late spring, less water is expected to make its way from the river into Lake Erie. And researchers don't expect any substantial rain the next few weeks.

"We're talking about months worth of loading in order to get to that big bloom, and we're getting close enough to the end of this loading season that they should be forecasting if it's going to be that big of an event," she explains. "And if it was just one big event, it's probably not going to be enough to change things drastically."

The typical bloom season runs from July to October. NOAA will issue a seasonal harmful algal bloom forecast on July 9, which features a more comprehensive prediction.

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