While the short-term news is good — Lake Erie’s harmful algae bloom forecast for the rest of this summer looks much better than last year — Ohio, Michigan and Ontario are failing to meet agreed-upon milestones toward reducing nutrient loads in the lakes, the fuel for the blooms.
The predicted severity index of algae blooms on western Lake Erie is 4.5, with 5 and higher considered more severe blooms, the National Oceanic and Atmospheric Administration, in conjunction with Ohio State University, the University of Michigan and others, announced Thursday. The index reached 7.3 last summer, with the highest severities ever recorded being 10 in 2011 and 10.5 in 2015.
“Much of the lake will be fine most of the time,” said Rick Stumpf, an oceanographer with NOAA’s National Centers for Coastal Ocean Science, adding that isolated areas could still encounter surface scum on particular days in the western lake basin, especially on calm wind and wave days.
Beyond being unsightly, smelly green gunk that impacts use of the lake, Lake Erie algae blooms can be harmful. They are made up of cyanobacteria, also called blue-green algae, that can produce the toxin microcystin, potentially harmful to both humans and wildlife. Unlike other types of water contamination, boiling water does not reduce the risk.
Some 500,000 people in and around Toledo had their water supplies disrupted for a weekend in August 2014 because of high levels of microcystin-producing algae in western Lake Erie, near the city’s water intakes. That prompted state, federal and provincial governments to redouble efforts to reduce the summer algae blooms, particularly through reductions in phosphorus, a key ingredient necessary for the blooms to grow.
In 2015, the governor’s offices in Michigan and Ohio, along with the premier of Ontario, set public goals of reducing nutrient pollution in the western and central basins of Lake Erie by 40% by 2025, with an interim goal of 20% reduction in 2020. But those goals have not been met.
Western and Central Lake Erie are projected to receive 325 tons of total “bioavailable” phosphorus — the type that supports algae growth in the lake — this spring and summer. While that sits almost exactly between the levels that reached the lake in 2018 and 2014, a 30% reduction in that amount would be required to reach the target goals the states and Ontario agreed upon, Stumpf said. It would take a 40% reduction over that level to make summer algae blooms negligible on the lake, he said.
The predicted moderate bloom shouldn’t be interpreted as significant progress toward meeting the Great Lakes Water Quality Agreement goal, because year-to-year changes are driven primarily by the amount of spring rain, said University of Michigan aquatic ecologist Don Scavia, a member of the forecast team. With the exception of large storms over a few days in late May, rainfall in Ohio’s vast Maumee River Watershed, a main tributary to western Lake Erie, was relatively scant.
“We can’t cross our fingers and hope that drier weather will keep us safe,” Scavia said.
“These blooms are driven by diffuse phosphorus sources from the agriculturally dominated Maumee River watershed. Until the phosphorus inputs are reduced significantly and consistently so that only the mildest blooms occur, the people, the ecosystem and the economy of this region are being threatened,” he said.
To-date, state and federal governments have mostly chosen to allow farmers to govern their runoff issues themselves, urging best management practices for fertilizer and manure application on fields.
“I’m not sure how we’re going to get (to a 40% reduction in phosphorus loads) by 2025, as the states keep putting the same management practices forward that have led to where we are,” said Tom Zimnicki, groundwater, surface water and agriculture program director for the Lansing-based nonprofit Michigan Environmental Council.
It’s difficult because of the vastness of the non-point sources of the phosphorus, said Christopher Winslow, director of Ohio State University’s Ohio Sea Grant, one of 34 NOAA Sea Grant programs throughout the U.S. dedicated to the protection and sustainable use of marine and Great Lakes resources.
“We’re talking many millions of acres in the western basin,” he said. “So there’s got to be a lot of activities on a lot of acres.”