The harmful algal bloom in Lake Erie this summer is likely to be smaller than average, according to the National Oceanic and Atmospheric Administration (NOAA).
Harmful algal blooms happen when algae, fed by farm fertilizer runoff, grow out of control. They clog water with a green scum and can emit unsafe levels of cyanobacteria that can be dangerous to people and wildlife.
This year’s bloom is forecasted to measure 3.5 on the severity index, with a possible range of two to four. The severity could be higher if July sees heavy rainfall. Last year’s bloom measured six on the severity index.
The severity index is determined by the size of the bloom during its 30-day peak. A bloom that measures over five on the index is classified as severe, while a bloom over seven is particularly severe.
Though an index of 3.5 means the bloom will likely be smaller and less severe than average, NOAA oceanographer Rick Stumpf said he hopes it will be even smaller.
“It’d be better if we were down at two or two and a half,” he says, “but at least we should be seeing smaller blooms, fewer scums as well.”
Blooms tend to begin forming toward the end of June, but aren’t generally visible until the second half of July. Recent temperatures could change when residents first see them, Stumpf said.
“One risk with temperature is if the lake continues to warm, we could see blooms starting earlier and lasting longer, but they won’t get bigger,” he said.
Some blooms in Lake Erie can produce toxins like microcystin, a known liver toxin, which poses a health risk to both humans and animals. Depending on a bloom’s severity, the presence of microcystin and similar contaminants can force nearby cities to further treat drinking water, or issue warnings not to consume it, and close beaches.
In 2014, Toledo banned residents from drinking tap water due to an extremely high toxin concentration caused by an extreme harmful algal bloom. The 2014 bloom measured above six on the severity index.
NOAA predicts blooms will be most prevalent near Lake Erie’s Western basin, the shallowest part of the lake. The Central and Eastern basins may see smaller blooms, particularly after stronger rainstorms.
Blooms usually recede in September, experts said, but it depends on wind patterns, which are impossible to predict this far in advance.
Stumpf says stay away from an algal bloom if you see one.
“Please keep yourselves, your kids, and your pets—your dogs—out of the water,” he said. “Every year a couple dogs in this country die by having swum in lakes with these kinds of blooms.”
