Great Lakes
A wet spring was bad for farmers, but gave algae less phosphorus to feed on.

This Summer’s Algal Bloom in Lake Erie Was Large, But Could Have Been Worse

This year’s algal bloom in western Lake Erie was about as bad as scientists expected. But it could have been worse.

The National Oceanic and Atmospheric Administration predicted another significant mass of algae in the lake in 2019, fed mainly by farm fertilizers containing phosphorus. Rain washes the chemicals into streams, rivers and creeks that flow into the lake. Phosphorus promotes the growth of microcystis cyanobacteria, a blue-green form of algae.

The amount of phosphorus flowing into the lake this season was within NOAA’s forecast of how severe the 2019 bloom would be.

“We use a scale of zero to 10,” says NOAA researcher Rick Stumpf. “This year’s bloom was a 7.3.” That falls within the range of 7 to 8 Stumpf and his colleagues predicted in July. At its peak, Stumpf says the bloom covered about 700 square miles of the lake’s surface.

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