By Gabrielle Nelson
Every summer, toxic algae blooms form on Lake Erie, posing a health risk to humans and animals. Image: National Centers for Coastal Ocean Science
Lake Erie’s annual algae bloom has begun to form weeks ahead of schedule off the coast of southeast Michigan, but scientists say they expect only a moderate bloom this year.
“There was scum off Monroe,” said Richard Stumpf, a National Oceanic and Atmospheric Administration oceanographer who leads the federal government’s bloom forecasting effort. “It’s not huge now, about 20 square kilometers (7.7 square miles), but it has actually started up in that area.”
Cyanobacteria, known as blue-green algae, fouls hundreds of square miles of western Lake Erie every summer, typically from July to October. The putrid, sometimes toxic, blooms pose a risk to human and animal health and the region’s tourism economy.
Under the right conditions, they produce harmful toxins that can sicken humans and kill pets.
The National Center for Coastal Ocean Science released this season’s forecast, predicting a bloom severity of 5 with a “potential range” of 4.5 to 6, similar to last year’s bloom of 5.3.
Moderate blooms have an index of 3 to 5, while an index above 5 indicates a more severe bloom. The highest severity index recorded in western Lake Erie was 10.5 in 2015.
The green blooms thrive in warm, shallow water that’s overloaded with nutrients like phosphorus, which makes Lake Erie an ideal breeding ground.
Each year, the lake absorbs millions of pounds of fertilizer and manure runoff from farms in Ohio, Michigan, Indiana and Ontario. The problem has persisted despite decades of effort to fix it.
Polluted runoff is worse during heavy rainfall. This spring’s rainfall was average, leading to a moderate bloom severity forecast.
Scientists said a heavy storm in the next few weeks could increase the forecasted bloom severity to as high as 7, but the chances of that happening are low.
Aside from rainfall, temperature also affects bloom formation. Stumpf said warmer temperatures this spring encouraged the bloom to form unusually early.
The national center has monitored the blooms with satellite data since 2002.
Although this year’s bloom is starting along Michigan’s coast, it’s not clear how much the algae will affect Michigan beaches this summer. Wind patterns this summer will decide what cities see the most blue-green algae, Stumpf said.
His message to anyone who notices green scum in the lake: “Keep your kids, yourself, your pets out of the water.”
You can check the center’s website for the latest updates on harmful algae blooms, their location and severity.
Gabrielle Nelson has an environmental reporting internship under the MSU Knight Center for Environmental Journalism’s diversity reporting partnership with the Mott News Collaborative. This story was produced for Bridge Michigan.