Children play while crews of volunteers from Ottawa Fire Services use their hoses to cool them off. (CBC)

Families that celebrated Canada Day at Ottawa's Petrie Island beach are watching their children for symptoms of E. coli infection after firefighters sprayed them with water contaminated with the bacteria.

High bacterial levels measured in the Ottawa River Monday kept the swimming areas at three beaches along the river closed Canada Day. The swimming area at a fourth beach at Mooney's Bay on the Rideau River was also closed.

Most people at Petrie Island in Ottawa's east end took care to avoid the water despite the warm, sunny weather.

When crews of volunteers from the Ottawa Fire Services arrived and used their fire hoses to cool off the crowd, many laughed and ran about, seemingly delighted — until they found out the water was being pumped straight from the river.

Liz Demelo, whose preschool-age son was one of the children playing under the spray, was upset she wasn't warned about the source of the water.

"I have definite issues around that as I have a three-year-old who doesn't necessarily know that he shouldn't swallow water when he's playing through the water that is being pumped," she said.

Municipal water brought in

After the CBC contacted the fire department about the issue, firefighters stopped using river water and brought in trucks carrying tanks of municipal water.

Irvin Sunstrum, sector chief for Ottawa Fire Services, said firefighters pump water from the river at the Canada Day festivities every year. (CBC)

Ottawa Fire Services sector Chief Irvin Sunstrum said firefighters have been helping celebrate Canada Day at Petrie Island for years, and have always pumped water from the river.

"And again, we started this year, not realizing the beach was shut down," he said. "I never checked, we just went ahead as in past practice."

He added that the fire department was just trying to offer enjoyment to the kids, never intended to endanger anyone and will check for beach closures if it repeats the event.

However, the department isn't sure it will be back next year, as it isn't worth organizing all its volunteers when the safety of the water is unpredictable.

City of Ottawa deputy city manager Steve Kanellakos said Wednesday that the city would begin informing all municipal departments, including the fire department, of "no swimming" advisories to prevent similar incidents in the future.

The city posts signs on the beach and flies a red flag when a "no swimming" advisory is in effect. Information about water quality at the beaches is also available over the web, on the phone or from lifeguards at the beach.