Toxic algae in Shubael Pond on Cape Cod captured by drone        Photo: Town of Barnstable

The “dog days” of summer are here, and so is the threat of toxic algae in lakes and ponds across the U.S. according to reports from news outlets nationwide.  The Boston Globe’s David Abel reported on how the 996 small lakes on Cape Cod that had provided a respite from saltwater are now warming so rapidly that they are being “transformed by climate change” that saps their oxygen, makes them dangerous for swimming by humans and pets, and harms wildlife.  The Environmental Working Group (EWG) tracks pet deaths due to toxic algae and they have seen them across the country this summer — in “Little York Lake, in Cortland, N.Y.; Cedar Lake, in Minneapolis; in Mantua Reservoir and the Virgin River in Zion National Park, both in Utah; and a private pond near Bozeman, Montana.”

Why This Matters:  Often these blooms occur because of runoff pollution, but in some locations on Cape Cod with little of that, the culprit seems to be climate change.  The bigger issue, EWG explains, is that “Sixty-eight percent of Americans rely on drinking water that depends on lakes, rivers or other surface water, according to the Environmental Protection Agency.” And often the toxic algae is not visible to the naked eye.

Cape Cod’s Algal Blooms

The Globe’s Abel explains that toxic algae have been increasing on the Cape in recent years, with a no swimming order imposed on small Shubael Pond, and again this year when dead fish were seen floating on guacamole-colored slime.  “’The bacteria like warm, calm places, without a lot of water or wind velocity, and these little lakes are their perfect breeding grounds,’ said Charles Culbertson, a microbial ecologist with the US Geological Survey’s New England Water Science Center,” and the amount of the toxic bacteria can even double every thirty minutes in the right conditions. Culbertson continued, “As temperatures rise, we’re going to see more of this, meaning many of the ponds on the Cape could become unswimmable. You won’t want to be breathing the air around them, either.”  This echoes health warnings for coastal blooms, where even being near the algae without going into it can make people sick.

Increasing 7x

Abel reports that “Last year, more than 500 such algae blooms were reported in the nation’s lakes, ponds, and rivers — 18 percent more than the year before and more than seven times the number reported in 2010, according to the Environmental Working Group, an advocacy group in Washington, D.C., that tracks algae blooms.”  And, “Late July through mid-October is considered the peak season for the blooms, which thrive on high temperatures, and local officials expect more closures.” Per their website, “The Environmental Working Group tracks and maps news reports of outbreaks going back to 2010. The number has risen steadily since then, with one-fifth more blooms in 2019 than the previous year. The federal government only tracks outbreaks of toxic algae blooms in the largest lakes, missing many bodies of water included in EWG’s map.”