Ontario E. Coli Probe Closes In On Cause

An investigation of the water supply in the southern Ontario town where North America’s worst E. coli outbreak occurred last month has eliminated some possible causes but failed to determine exactly what happened, officials said Friday.

At least seven people have died and hundreds more sickened by the intestinal bacteria that turned up in Walkerton’s drinking water more than two weeks ago. Four more deaths possibly linked to the E. coli contamination also are being investigated by the Ontario coroner.

Steve Burns, a construction consultant assisting the investigation of Walkerton’s water, said Friday the focus had been narrowed to the town’s three wells and its aquifers.

Burns said testing of the entire water supply that began last week appeared to rule out other suspected causes. In particular, he said a May 12 storm that flooded Walkerton no longer was considered the cause of the contamination.

The flooding could have overloaded one of the wells, Burns said, but officials believe the source of the widespread contamination involved the wells or aquifers.

Residents of the town of 5,000 about 90 miles west of Toronto must wait at least six to eight more weeks before the water is safe to drink, municipal officials said Friday.

Walkerton has been under a boil order for its water since May 21, days after the first cases of bloody diarrhea alerted health officials to a possible contamination.