The western side of Lake Erie may see a boom in harmful algal bloom this summer that could match recent years but not pass the record in 2015, a new report warned Thursday.
University of Michigan researchers said western Lake Erie “will experience a significant harmful algal bloom” in a forecast made public by the National Oceanic and Atmospheric Administration that funded the research.
The final seasonal forecast said algal levels could match those in 2013 and 2014, but the level of toxicity is unknown.
“This year's bloom is likely to be significantly larger than the average, approaching some of the largest blooms on record, including the one that caused the city of Toledo to issue a 'do not drink or boil' advisory in 2014,” said UM aquatic ecologist Don Scavia, a member of the forecast team.
Western Lake Erie covers Monroe County in Michigan and the Toledo area in Ohio. The 2014 bloom resulted unsafe drinking water for two days in August affecting more than 400,000 area residents.
Officials have since developed a broad safety designed to avoid a repeat of the algal-bloom-contaminated water.
The Lake Erie bloom is predicted to measure 7.5 on the severity index but could range between 6.5 and 9, researchers said. An index above 5 indicates a potentially harmful bloom.
The index measures a bloom’s biomass and the amount of its harmful algal over a sustained period.
The toxins in a large bloom may not be as concentrated as in a smaller bloom. NOAA is developing tools to predict how toxic blooms will be.
“But bloom predictions — regardless of size — do not necessarily correlate with public health risk,” Scavia said. “Local weather conditions, such as wind direction and water temperature, also play a role. Even so, we cannot continue to cross our fingers and hope that seasonal fluctuations in weather will keep us safe.”
Much of the lake is expected to be algae-free throughout the bloom season, said Christopher Winslow, director of the Ohio Sea Grant College Program.
Elevated phosphorus from watersheds are the main cause of the lake’s algal blooms. An estimated 85 percent of the phosphorus entering Lake Erie from the Maumee River come from agricultural sources, researchers said.
The rainy weather in May is a factor in the relatively high spring phosphorus load into the lake, researchers said.
“Until the phosphorus inputs are reduced significantly and consistently so only the mildest blooms occur, the people, ecosystem and economy of this region are being threatened,” said Scavia, who is a professor of natural resources and environmental engineering.
The forecast team also included Daniel Obenour of North Carolina State University, UM’s Isabella Bertani and Nathan Manning, and Drew Gronewold and Craig Stow of NOAA’s Great Lakes Environmental Research Laboratory in Ann Arbor.
“A bloom of this size is evidence that the research and outreach efforts currently underway to reduce nutrient loading, optimize water treatment, and understand bloom dynamics need to continue,” Winslow said.