Scientists are warning that conditions are perfect for a bumper crop of algae to grow in Lake Erie this summer.

They say heavy April showers are washing fertilizer off farm fields into the water in larger amounts, and those chemicals feed algae blooms that starve the lake of oxygen. Feeding on phosphorus, algae produces bad smells and toxins that are absorbed by underwater life, choking it off.

"There's a 99 per cent chance, there's a strong chance, that [we will] have very bad algae this year," said Raj Bejankiwar, a scientist with the International Joint Commission.

The warning comes two years after Lake Erie experienced the worst algae blooms on record.

By the numbers

  • Approximately 40 million people live around the Great Lakes.
  • About 73 million tourists visited the Great Lakes in Ontario in 2010.
  • About $12.3 billion was injected into the economy by those tourists.

Source: IJC

Blooms are traditionally confined to the summer months, mainly August. Last year, however, warmer temperatures in March allowed algae to grow earlier in the year, but the bloom wasn't as big as the one witnessed in 2011.

This year, April rain could cause as big a bloom as the one from two years ago. Heavy spring rain was to partially blame for that one, too.

Phosphorus gets from the fields to the lakes in one of three ways:

  • Blown there by the wind.
  • Soaking through the soil, entering the ground water and flowing into rivers and lakes.
  • Rain washes it off the top of the soil and directly into rivers and lakes.

Bejankiwar is the lead on the Lake Erie Ecosystem Priority, a branch of the IJC that is studying algae levels in Lake Erie. He said it's normal to have some algae in the lake, but not massive blooms.

Bejankiwar said extra nutrients that feed algae also come from sewage treatment plants, recreational properties and golf courses. He said most of the phosphorus comes from farm run-off.

It's not much phosphorus per farm or per hectare, but it adds up, says one professor.

"If we're talking about the amount a farmer would lose, we're talking less than a few grams per hectare," said Ivan O'Halloran, a professor at Ridgetown College.

O'Halloran said that one kg of phosphorus run-off can have a "significant impact" on algae levels.

'No fertilizer police'

He said one way farmers try to decrease the amount of phosphorus that ends up in the lakes is to make sure they only put what they need into the soil. Soil tests can be done to see how much fertilizer is necessary.

However, there are no "fertilizer police," and best management practices are not laws: they are suggestions, O'Halloran said. That all makes it hard to regulate the distribution of fertilizer.

Henry Denotter, a Kingsville farmer, plants ground cover in the fall to keep the fertilizer from washing into the ditch. After the wheat is harvested, Denotter plants beets and clover in his wheat field to keep the soil in place. Even then, some phosphorus always escapes, he said.

"We do whatever we can to try and retain it, but we have to stay in business, too," Denotter said.

Denotter said it's impossible to keep all the fertilizer in the soil and dire predictions from scientists won't change that.

He thinks scientists should recognize there is only so much farmers can do.

Denotter already uses GPS to determine where he needs to fertilize; uses soil tests to determine how much fertilizer he needs; and uses what he calls a "no-till" system, where he doesn't turn up the earth.

Denotter said it's in farmers' best interest to do what they can to keep the phosphorus in the soil because it costs about $700 per tonne.

Last fall, the Essex Region Conservation Authority and Windsor-Essex County Environment Committee launched an educational campaign about blue-green algae. It's called Overload: Lake Erie Blue Green Algae.