TOLEDO, Ohio -- Lake Erie will see one of the most severe toxic algae outbreaks in recent years this summer, a year after toxins contaminated the drinking water for 400,000 people in northwestern Ohio and southeastern Michigan, researchers predicted Thursday.
Scientists who issued their forecast for the lake think this year's algae bloom could be second only to one in 2011, when the algae stretched more than 100 miles from Toledo to Cleveland.
Heavy rains across northern Ohio over the past month have washed huge amounts of algae-feeding phosphorus into the lake.
The prediction for an algae bloom bigger than a year ago doesn't necessarily mean there will be more drinking-water trouble because wind and water temperatures play a role, too.
"While we are forecasting a severe bloom, much of the lake will be fine most of the time," said Richard Stumpf, of the National Oceanic and Atmospheric Administration.
Algae blooms -- linked to phosphorus from farm fertilizers, livestock manure and sewage treatment plants -- have taken hold in the western third of the lake over the last decade and colored some of its waters a shade of green that looks like pea soup.
Over the past two summers, toxins in the lake fouled the water supply in Toledo and in a neighbouring township. Toledo's drinking water was off-limits for just over two days last August.
The algae blooms, which typically peak from the middle of August through the end of September, also have been blamed for contributing to oxygen-deprived dead zones where fish can't survive.
What happens this year when the large blooms develop will depend a great deal on wind patterns and temperatures -- the cooler the better for slowing down the algae.
In past summers, strong winds have pushed the blooms up against the Ohio shoreline while at other times it has sent the algae toward the middle of the lake. A year ago, the wind shoved the algae over the intake pipes where Toledo draws its water.
"There's no way now to know where it will be concentrated," Stumpf said.
Ohio, along with Michigan and the Canadian province of Ontario, agreed in June to sharply reduce the amount of phosphorus flowing into western Lake Erie within the next 10 years.
Some changes limiting when farmers can spread fertilizer and manure on fields already have been made, but it will take at least a few years to see improvements.
Only a significant reduction in phosphorus will solve the problem, said Don Scavia, a University of Michigan aquatic ecologist. "We cannot continue to cross our fingers and hope that seasonal fluctuations in weather will keep us safe," he said.
About half the phosphorus in the lake comes down the Maumee River, which drains 3 million acres of farmland before flowing through Toledo and into the lake.
So far this year, about 2.5 million pounds of phosphorus has washed down the river -- the highest since 2011, said Laura Johnson, a research scientist at the National Center for Water Quality Research at Heidelberg University.
Nearly half of this year's total in June came after storms dumped 8 inches of rain across northwestern Ohio and parts of Indiana that also drain into the lake.
Researchers who have been out on the lake already have seen the toxic algae in the water, which is a little earlier than usual, Tom Bridgeman, of the University of Toledo's Lake Erie Center.
But the toxins have not been detected in the water Toledo uses, city officials said this week.
