The forecast is in: the green goo will be back on Lake Erie this year, but it won’t be as bad as last year.
The big, ugly blooms of cyanobacteria (sometimes referred to as blue-green algae) happen when excess nutrients — mostly phosphorus — run off into the lake from farms and sewage treatment plants. Some of these kinds of cyanobacteria produce toxins can harm pets and make the water unsafe to drink.
Rick Stumpf is an oceanographer with the National Oceanic and Atmospheric Administration. He says they’re predicting this year’s bloom in Lake Erie will be significant, but not as bad as it has been in recent years. The blooms reached a record level in 2011.
"We have a severity index and 2011 is a 10 on this index and last year, unfortunately, was the second worst bloom that we've seen since 2000. That was an eight. This year we expect it on a scale from about five to maybe six," says Stumpf.
Spring rain and fertilizer
Stumpf says the key predictor is how much rain there is in the spring. Too much spring and early summer rain can flush phosphorus from farm fields into the lake. A key source of phosphorous is the Maumee River Basin. Last year's bloom was large due to a relatively wet spring followed by a wet July.
"This year we're a little drier this spring than it was last year. So the total amount of phosphorous going into the lake is less," Stumpf says.
He adds that despite the forecast, the extent of the bloom varies and depends on the wind.
"So there's not a bloom everywhere all the time. And there will be many places on the lake — on or around the western basin of the lake — that will be great to go to."
The National Oceanic and Atmospheric Administration has established a Center of Excellence for Great Lakes and Human Health.
The Center provides a weekly forecast for harmful algal blooms via its HAB (Harmful Algal Blooms in Lake Erie) bulletin.
Clarification: An earlier version of this story referred to "algae blooms" in Lake Erie. These are really bacterial blooms (cyanobacteria) that look like algae. The copy has been clarified above.