Capital Health is warning boaters and swimmers to stay away from oil patches and tar balls in Lake Wabamun, exactly two years after a train derailment dumped 1.3 million litres of heavy bunker fuel oil and wood preservative nearby.

Hot weather has increased the oil sheen and the number of tar balls and oil patches in parts of the lake west of Edmonton, especially Ascot Beach, Rizzie Beach, Rich's Point and Point Allison, said medical officer of health Gerry Predy.

Predy is also warning people to stay away from oily aquatic vegetation on the beach or in shallow water.

The spill happened on Aug. 3, 2005, when a CN freight train left the tracks in the village of Wabamun, Alta.

Kate Campbell, who runs the Wabamun Lake Inn, said the water seems clean where she lives, but the effects of the disaster can still be seen in other areas of the lake. 

"Where the actual spill was along the reef beds and some of the areas where it collected yes, you will still see it coming up or shimmering on the water. So that's something that I guess we learn to live with until it's totally clean. And will it ever be totally clean? I guess that's something no one knows except nature."

People who come into contact with the tar or oil should wash with soap as soon as possible, says the health region. Pets should also be cleaned with soap. Medical attention is necessary if some of the affected water is swallowed, or an unusual skin rash develops.