He smelled it before he saw it.

It reeked of rotting fish, or an open sewer. It was strong. Nauseating.

Then Jeff Vidler came face-to-face with “this slimy, thick green stuff floating on water. It had even washed up on the shore.”

He knew what it was: toxic blue-green algae. It was spread as far as he could see at a beach near Port Glasgow, a tiny community about 75 kilometres southwest of London, Ont. The stuff was bobbing up and down in little waves, in different shades of green.

Vidler, a harbourmaster at Erieau, another small Lake Erie cottage community close to Port Glasgow, had seen small quantities of it before, but never “that sea of algae.”

“It was scary . . . what the lake looked like,” he says.

That was the summer of 2011, the year blue-green algae invaded Lake Erie with the largest bloom in recorded history, covering as much as one-sixth of the surface. The bloom extended from Toledo, Ohio to beyond Cleveland and along the Ontario shore. It extended over 20 kilometres from the shores, and in the central basin it was observed at a depth of at least 60 feet.

It’s a memory cottagers, beach-goers, boaters and businesses related to tourism would like to forget.

But that may be difficult in 2013. For the algae could be as bad, or worse, this summer.

Weather forecasters point to a wet spring.

That prediction is worrying for scientists because the rainier the weather, the worse the outbreak of algae.

Swathes of blue-green algae are caused largely by phosphorus runoffs, researchers say. Phosphorous is used as fertilizer and is also in manure and other waste products from agri-business operations such as pig farms and greenhouses.

Algae thrive on phosphorous.

“When it rains a lot, we see more phosphorous runoffs,” says Raj Bejankiwar, the lead scientist of the International Joint Commission’s Lake Erie Ecosystem Priority (LEEP). “This year, if the weather forecast is accurate, there is possibility of high phosphorous runoffs.”

He doesn’t know how bad it could be but gently reminds that “2011 saw a wet spring and the lake was invaded by algae blooms.

“It was pretty bad.”

The algae caused closure of dozens of beaches in Canada and the U.S., making a considerable dent into tourism. The density of the algae also slowed down boats.

As long as algae are alive, they float on the surface. When algae die, they sink to the bottom of the lake, where they decay and suck oxygen out of the water, killing fish. Hundreds of thousands of dead fish washed on on Erie’s shores in September 2011, triggering panic among those who live by the lake.

Not all types of algae, a simple aquatic organism, are destructive; in fact, some are beneficial to other aquatic life. But blue-green algae can contain E. coli bacteria, which is harmful when ingested by humans or pets. It may also contain cyanotoxin, which can cause skin irritation, respiratory difficulty and gastrointestinal distress in humans.

Blue-green algae also thrives on light. Lake Erie is the shallowest of the Great Lakes, especially at its west end, and thus more susceptible to algae than its deeper cousins, which do not have the same penetration of sunlight

Algae blooms are not a new problem in Lake Erie. In the 1960s, parts of Lake Erie were declared biologically dead because of algae invasion. People on both sides of the border gave up on it.

Then, in 1972, Canada and U.S. signed the Great Lakes Water Quality Agreement, which saw a multibillion-dollar investment to reduce the amount of phosphorous flowing into the lakes. Governments worked hard to get rid of phosphorous in detergents, improved sewage treatment plants and drastically changed farming practices.

The two countries called for an annual cut of more than 12,000 tonnes in phosphorus use. At the urging of officials and conservation agencies, hundreds of Lake Erie-area farmers changed their farming practices to reduce the amount of the chemical that washed away with dirt from their fields.

The strategy worked, and Lake Erie recovered.

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But in 2000, blue-green algae reappeared in Lake Erie. And 2011 was the worst year ever.

Climate change, say scientists, is the new culprit in the algae conundrum.

Lake Erie’s waters are warmer, and rain showers are more intense, causing more phosophorus runoff, says John Nevin, who works with the International Joint Commission’s Lake Erie Ecosystem Priority. “It makes for perfect conditions to cause algae droves.”

The lake got a break in 2012: it was comparatively dry, and so there were fewer algae blooms.

Deforestation, primarily because of real estate development in recent years, has also played a role in the return of the slimy green sheet, researchers say. Fewer trees on the banks of streams means that more phosphorus gets into waterways and eventually into lakes.

But where is all this phosphorous coming from?

That is one of the main questions LEEP is trying to answer, says Nevin. “There are some theories but the key element is to figure out why and what to do (about it),” he says. He notes that there appears to be a new form of phosphorus draining into the lake, one algae feed on more readily.

Can Lake Erie be cleaned again?

In February, under the auspices of the International Joint Commission, scientists from Canada and the U.S. met in Windsor to focus on the sources of algae, the impact of climate change and solutions to the problem.

Experts say there is no one solution, but an obvious thing to do is to cut phosphorus levels once again.

LEEP’S Bejankiwar says there’s a certain urgency to cutting it back. “Algae are already causing an economic impact,” he notes. It is difficult to put a dollar value on it because the lake straddles a big geographical area in two countries, but “there is evidence that it is impacting fishing, recreational use of water, tourism and even drinking water.”

Farmers and others who live on the shores of the Great Lakes need to be educated about the impact of algae blooms, says Geoff Peach, the coastal resources manager for the Lake Huron Centre for Coastal Conservation in Goderich, Ont.

Algae blooms are not as big a problem in Lake Huron, but in the past decade they have shown up, and according to some observers, they have grown larger every summer.

It is impossible to predict whether 2013 will be a bad year for Lake Huron, “but if there is enough phosphorous and heavy rains, and if water temperature goes up, we expect it could be a big problem,” says Peach.

His non-governmental agency has been raising awareness with farmers. “Public education is the one way to deal with it,” he says.

“We can work on causing less phosphorous runoffs.”

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