Federal officials are investigating after a heating and cooling plant leaked thousands of pounds of a chemical commonly used in air conditioners into the Ottawa River.
The spill started at a government building at Tunney's Pasture at about noon on Monday and was discovered 24 hours later.
Despite the spill, which dumped 6,000 pounds of Freon-22 into the river, city officials say Ottawa's drinking water is safe because the chemical was not a high enough concentration to pose a risk.
The Ottawa River has been the site of several spills in recent months and environmental activists are urging the federal government to move forward with tougher drinking water standards.
"The levels of radioactive tritium in Ottawa's drinking water are routinely two, three sometimes four times above background level for tritium, and this is because of these nuclear facilities on the banks of the river," said Ottawa riverkeeper Meredith Brown.
Members of the Tritium Awareness Project say Canada is the world leader in production of the radioactive material. In December and February, the group says the AECL nuclear plant in Chalk River leaked large amounts of radioactive tritium into the air and the Ottawa River.
"We think that some of the citizens of Pembroke are some of the most highly exposed residents to tritium anywhere in the world," said Lynn Jones a member of Renfrew County Concerned Citizens.
The Canadian Nuclear Safety Commission has responded to the group, saying in a letter that any "releases of tritium to the river have been controlled and monitored, within environmental standards."
The commission added: "at no time was the public or the environment at risk."
But the group says that's not a good enough answer. Now they're demanding an independent investigation into the quality of Ottawa's drinking water.
"Who is looking after the Canadian public interest?" said Gordon Edwards of the Canadian Responsibility Coalition.
"When a low dose of carcinogen is administered to a large population of people, the number of cancers that result is proportionate to the number of people exposed. This is why we keep it out of drinking water."
With a report from CTV Ottawa's Catherine Lathem
