A blue-green algae warning has been issued for Lac Ste. Anne, in the middle of the annual pilgrimage to the Alberta lake.

People visiting the lake west of Edmonton are being advised not to drink the water, not to swim or wade in the lake and to limit their consumption of its fish.

They are also advised to avoid contact with blue-green algae along the shoreline.

Blue-green algae produce a toxin that can cause serious illness to those who drink or come into contact with the water.

Thousands flock to Lac Ste. Anne each summer to bathe in the water as part of the annual spiritual pilgrimage.

This year's event began Sunday and runs until Thursday. There is no word yet on how the algae warning is affecting it.