TORONTO - Ottawa and the provincial government must take action to protect members of a northwestern Ontario First Nation whose water and fish are contaminated with mercury, residents said Wednesday.

Dozens of residents made the 1,800-kilometre trek to Toronto to take part in a march to the legislature. They held aloft a sea of blue fabric and cardboard fish to make it look like a river was flowing toward the legislature.

"That's a very basic life for us to have clean drinking water," said Grassy Narrows resident Judy Da Silva.

"That's why we walk through this city, mimicking the way the river flows. Because in a lot of places the water has stopped flowing in a clean way and it has become our poison."

Ontario regional Chief Angus Toulouse said the government needs to establish permanent monitoring for Grassy Narrows' water.

"We all know water is the most sacred," Toulouse said.

"It gives life to us. Without water we're not going to survive. We need to make sure that the government acknowledges this."

A study released this week suggests the health effects of mercury poisoning on the Grassy Narrows First Nation are worse now than in the 1970s. The report was released by the group Earthroots, which said between 1962 and 1970 a paper mill in Dryden dumped the equivalent of about 9,000 kilograms of mercury into the Wabigoon River.

When Dr. Masazumi Harada, a Japanese mercury expert, first visited Grassy Narrows in 1975 he found people with mercury levels more than three times the Health Canada limit.

Health Canada stopped testing for mercury in Grassy Narrows residents, claiming that it was no longer a problem because mercury levels have fallen below its safety guidelines.

Grassy Narrows residents now are demanding governments acknowledge the mercury poisoning in their people and strengthen federal mercury guidelines.

"We've been affected by the pollution, this poisoning that's in our bodies today," said Grassy Narrows Chief Simon Fobister.

"Our health condition is worsening, generation after generation and this has got to stop."

The residents who made the long journey Wednesday to Toronto said many of them have numbness, tremors and babies are often born with birth defects and other conditions they blame on the mercury.

It's for the children that the people of Grassy Narrows fight, said resident Chrissy Swain.

"It's a fight for us every single day that we wake up we have to look at our children and think about them," she said.

"The land is part of who we are. We should be able to go out and hunt and fish...If all that is gone, then who are we?"

This is not just a First Nations issue, it's a human rights issue, said Treaty 3 Grand Chief Diane Kelly.

"The North is not a wasteland," she said. "It may be sparsely populated but there are people living there. The land in Treaty 3 has extreme value to our people spiritually (and) culturally and we cannot disconnect form that relationship we have."

Premier Dalton McGuinty said this week that he wants to take a good look at the Earthroots report before deciding whether to act.