The Quebec environment department is earning praise from international scientists for acting quickly on the blue-green algae contaminationin the province's lakes and rivers. In other parts of the world the problem is much worse.

More than 1,500 scientists are attending a conference on water issues in Montreal this week.

The blue-green algae now affects more than 100 lakes and rivers in Quebec, and it's onTuesday's conference agenda.

"It's been very important that people are finally becoming aware of the problem in Quebec. It's been something that's been a problem throughout the world," said conference organizer Beatrix Beisner, a professor of biology at the Université du Québecà Montréal.

That's a fact Iowa State University professor John Downing is all too familiar with.

He said some lakes in Iowa are 100 times worse off than lakes in Quebec. He said blue-green algae can literally pile up along the shoreline.

Downing said Quebec has done a much better job of responding to the problem early.

"If you let it go too long, it can be pretty much irretrievable. You can get to the point where you'll never get back to that nice natural state," he said.

Downing says Iowa has learned its lesson the hard way and some lakes havebeen irreparably damaged.

Iowa expects to spend $30 million just to restore one lake, Downing said.

Blue-green algae, also known as cyanobacteria, are micro-organisms that grow in warm, slow-moving water and sometimes form visible coloured "blooms" on the surface of the water.

Some kinds produce toxins that can irritate the skin and eyes of people who swim near them, or cause symptoms such as fever or headaches if swallowed in large quantities.

The Montreal conference on water issues continues until Saturday.