Canada and the United States will renegotiate the Great Lakes Water Quality Agreement, U.S. Secretary of State Hillary Clinton said Saturday in Niagara Falls, Ont.

Clinton, who was joined by Foreign Minister Lawrence Cannon, crossed the border for celebrations marking 100 years of the Boundary Waters Treaty between the two countries.

"We have to update it to reflect new knowledge, new technologies and, unfortunately, new threats," Clinton said.

"The rivers, the lakes, the streams, the watersheds along our boundary do not belong to one nation, they belong to all of us," she said at celebrations overlooking the falls.

"The friendship between Canada and the United States is a model for the world," said Cannon.

But, he also had some pointed comments on efforts to hinder, rather than promote, trade between the two countries.

"Free trade has been — and still is — a driving force between our countries, one that will help pull us out of the global economic downturn," Cannon said, as Clinton looked on.

"Protectionism can only bring everyone down," he said.

Formed in 1909, the Canada U.S. Boundary Waters Treaty is aimed at resolving disputes "primarily those concerning water quantity and water quality along the boundary between Canada and the United States," according to the website of the International Joint Commission that administers the treaty.

"It is so wonderfully easy to travel between our two countries," Clinton said, noting that an estimated 300,000 people cross the border "every single day."

Still, travel between the two countries has recently become tighter with the introduction on June 1 of the Western Hemisphere Travel Initiative.

Starting June 1, border guards began requesting passports as Canadians crossed into the United States as the new measure officially came into effect.

For now, anyone who doesn't have a passport will still be allowed to cross the border, as long as they have such things as a birth certificate and picture identification.

Speaking at a news conference later, Clinton said she and her officials were working to make sure that enhanced security measures do not overly interfere with movement across the border.

"We will work very closely with the Canadian government," she said.

As well, both Clinton and Cannon said discussion over water will include the Arctic.

"We don't want the Arctic to become a free-for-all," Clinton said.