Indigenous chiefs and elders, leaders of the Bloc Quebecois and Green Party, and several environmental groups are pushing back against a Canadian Nuclear Safety Commission decision last month to approve the waste site in the town of Chalk River, 180 kilometers (110 miles) north of Ottawa.

"The disposal site is only one kilometer from the Ottawa River, and we're worried about leakage," protestor Tammy Pizendewatch Twashi told AFP.

The river provides drinking water to the capital's more than one million residents and 140 nearby communities.

"Water is life," said Chief Lance Haymond of the Kebaowek First Nation, speaking to a small crowd outside Parliament. "We need to protect it."

The tribe has launched one of several legal challenges of the project.

Haymond expressed concerns that any river pollution could lead to health issues and spoil habitat for bears and a number of at-risk animal and plant species.

The disposal facility at Chalk River Laboratories is to store up to one million cubic meters (35.3 million cubic feet) of nuclear waste.

Chalk River Laboratories was built in 1944 and was the site of the world's first nuclear reactor meltdown in December 1952, and saw one again in 1958.

Before being decommissioned, the lab developed nuclear reactors, conducted nuclear weapons research, and was at one time a major supplier of medical isotopes used to diagnose and treat cancers.

The Canadian Nuclear Safety Commission said in a statement that it would store mostly contaminated materials from environmental remediation and the decommissioning of the site in 2018, as well as from its past operations as a nuclear laboratory.

Waste from hospitals and universities would also be shipped there to be stored in the "containment mound."

The regulator insisted that the project "is not likely to cause significant adverse environmental effects," and Prime Minister Justin Trudeau on Wednesday declined to intervene.

"This is not a political decision," he told the Commons, adding that it should be left to experts.