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The Great Lakes Are Alive With Toxic Ooze

Predictions of a “severe” algae outbreak in 2015 look to be on track.

NASA/USGS

From the sky, you’d be forgiven for thinking parts of the Great Lakes are growing grass. The algae blooms this year are so thick they look like well-fed lawns, albeit ones that could suck you down into the ooze and maybe poison your dog with algal toxins, to boot.

Last month, scientists predicted a “severe” outbreak of algae in Lake Erie, writing:

The effects of the cyanobacterial blooms include a higher cost for cities and local governments to treat their drinking water, as well as risk to swimmers in high concentration areas, and a nuisance to boaters when blooms form. These effects will vary in locations and severity with winds, and will peak in September.

The bloom will be expected to measure 8.7 on the severity index with a range from 8.1 to potentially as high as 9.5. This is more severe than the last year’s 6.5, and may equal or exceed 2013, which had the second worse bloom in this century. The severity index runs from a high of 10, which corresponds to the 2011 bloom, the worst ever observed, to zero. A severity above 5.0 indicates blooms of particular concern.

To judge from these July 28 satellite images, the algae are already enjoying a healthy adolescence. Lake St. Clair is smeared with gloppy green along its southern coast, as seen above, and the western part of Lake Erie looks like Nickelodeon’s slime factory suffered a massive leak:

NASA/USGS

The algae are thriving thanks to warm temperatures and nutrients from agricultural operations (like phosphorus) running into the water. If ingested by humans, they can damage organs, irritate nerves, and cause flu-like symptoms; in some animals their toxic byproducts can be fatal. Last August, noxious algae forced Toledo and Southern Michigan to turn off the drinking water, leaving 400,000 people to suck on bottled beverages. So far this month, though, the region’s water is reportedly safe to drink.

About the Author

  • John Metcalfe
    John Metcalfe is CityLab’s Bay Area bureau chief, based in Oakland. His coverage focuses on climate change and the science of cities.