It turns out that NBA superstar LeBron James isn’t the only one returning to the Midwest.

Late summer will see a return of cyanobacteria, the toxic, oxygen-depleting blue-green slime that has been plaguing Lake Erie in recent years, according to NOAA scientists. This year’s bloom isn’t expected to be quite as bad as last year’s intense algae or the record-setting bloom in 2011, which covered 1,930 square miles of water. But it’s still probably going to cover a large stretch of the lake’s western portion, according to NOAA scientists.

NEWS: Why Lake Erie is Under Attack from Algae Blooms

Cyanobacteria is a pretty color in satellite photos, but it’s a major public health and environmental hazard that can make people and pets sick and kill fish and aquatic plants.

Algae blooms are a natural part of the life cycle of an aging lake, according to the U.S. Environmental Protection Agency, but their intensity is being exacerbated by phosphorus runoff from agriculture, lawn care and other human activity. About 80 percent of the land in the Great Lakes watershed is used for farming, and much of it drains into the shallowest portion of Lake Erie, according to this PLOS ONE article on the blooms.

Lake Erie’s summer blooms tend to be a particular type of cyanobacterium called Microcystis. The latter is a greenish, thick, paint-like, sometime grainy material that accumulates along the lake shore. As this EPA primer notes, dried Microcystis scum — wow, even typing that makes us wrinkle our noses in disgust — may contain high concentrations of bacteria for several months. That allows toxins to dissolve in the water even when the cells are no longer alive or after a recently collapsed bloom.

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Such blooms are a big problem in waters in other parts of the United States and the world as well. In 2013, the Chinese seacoast off the city of Qingdao was plagued by a giant bloom of an algae called Enteromorpha prolifera, which turned waters green and required the use of bulldozers to remove more than 7,300 tons of scum from beaches. Fortunately, at least, that algae wasn’t toxic, but it did suck oxygen from the water and block sunlight, killing local marine life.

Photo: This summer’s toxic algae bloom in Lake Erie won’t be quite as bad as the one from 2011, pictured above. But it still is a major environmental problem. Credit: NOAA