2021 Harmful Algal Bloom (HAB) forecast: smaller than average

Projected range of 2 to 4.5 on a 10-point scale, following fairly dry spring
Published: Jun. 30, 2021 at 6:30 PM EDT
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TOLEDO, Ohio (WTVG) - With summer heat in full swing, we’re watching and waiting for green algae to start reappearing in western Lake Erie. Toledoans are no stranger to the effects of harmful algal blooms, or HABs, as we’re coming up on 7 years since the Toledo water crisis which left 110 people sick.

“You go back to 2014, when we had the massive algal bloom affecting the metropolitan Toledo area, where over 500,000 people did not have drinking water for several days,” recalled Rep. Bob Latta (R-OH) in Wednesday’s annual HAB forecast conference, with NOAA and other partners.

While we still can’t judge how toxic a bloom will be, this year’s HAB forecast is promising: a range of 2 to 4.5 (on a 10-point scale), averaging about 3 -- very similar to 2020, which ended up being overestimated by most models. The peak is expected in mid to late July.

The projected range for this year's western Lake Erie algal bloom averages a 3 on a 10-point...
The projected range for this year's western Lake Erie algal bloom averages a 3 on a 10-point scale -- similar to 2020.(NOAA/Heidelberg Univ./U. Michigan/Stanford/Carnegie)

Rick Stumpf from the National Centers for Coastal Ocean Science says last year’s result lead to a slight tweak in modelling this year, though their methodology has improved over the years. “For the first time in over a decade, we’re actually looking at two consecutive years with a relatively mild bloom -- and we’re now starting to get to the point of having data to do a better job of observing those blooms,” says Stumpf. “My group is working with high-resolution satellite data to pick those blooms up better, and the Great Lakes Lab has been experimenting with some aircraft flying along the coast.”

Curiously, we’ve alternated high and low blooms for the last decade or so -- higher for odd years, lower for even years. 2011 was viewed as a “perfect 10″ in terms of HAB extent, yet 2015 even managed to beat the high score, as it were. Comparatively, 2018 and 2020 had below average spring runoff overall -- much like this year, which factors heavily into the 2021 projection. It’s important to note that, while 2019′s very wet spring led to a high HAB level (7.3), Laura Johnson -- director of the National Center for Water Quality Research -- says a lack of phosphorus/fertilizer runoff from unplanted fields meant it could’ve been a lot worse for northwest Ohioans leading into that summer.

Wind can also prove a wildcard for these seasonal forecasts. Stumpf points out that “southwest wind will tend to keep the bloom further out and disperse it in the middle of the basin, with worst case being calm wind conditions.”

Rep. Marcy Kaptur (D-OH) underscored the importance of these annual projections for Ohioans and Michiganders alike: “Toxic algae covers our shores, and threatens our future. Our regions, our fishermen, our boaters and water treatment operators rely on this forecast. HABs impact the daily lives of over 11 million people who depend on the lake for fresh drinking water.”

Click here to monitor the weekly Lake Erie HAB bulletins and satellite imagery through the summer.

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