The site of the old pulp and paper mill upstream from Grassy Narrows First Nation is very likely still leaking mercury into the river, a new scientific study has found.

The scientists made this conclusion after their recent tests of the riverbed mud revealed that at the area where the Wabigoon River passes the plant site, the mercury in the sediment soars “super high” to 130 times normal levels.

“(This is) strong evidence that the mill site is an ongoing source of mercury to the river,” the report said. “This warrants further investigation of the former … plant site and its surroundings.”

The province recently announced it is “completely committed” to finding and cleaning up the mercury. These new test results “greatly clarify the pathway” to fixing the problem, the report said.

Between 1962 and 1970, the Dryden paper plant, then owned by Reed Paper, dumped 10 tonnes of mercury into the river. The site of the plant, now owned by Domtar, is about 100 kilometres upstream from Grassy Narrows and nearby Whitedog.

There is no suggestion that Domtar, a pulp manufacturer several owners removed from Reed Paper, is responsible for any source of mercury.

Mercury contamination, a serious health risk, still plagues these indigenous communities in northern Ontario. The river has not cleaned naturally, and scientists have wondered if it is still carrying mercury downstream. But the province had denied the possibility that the site of the old mill could be responsible.

“Now we have strong, circumstantial evidence that there’s leakage going on,” Dr. John Rudd, one of the scientists, told the Star. “If this finding is confirmed, it would mean that there has likely been ongoing contamination all this time.”

This dramatic finding was not brought to light sooner because the provincial government has not tested the river in the area since 1980.

“I’m very disappointed that Ontario didn’t do any more monitoring over the years,” said Grassy Narrows Chief Simon Fobister. “If they had done so, they would have known earlier that there was still mercury being leaked from the old mill site and they probably would have done some remediation a long, long time ago.”

As recently as last year, officials have said that the site of the old mill was not a source of mercury and that a river cleanup was not necessary.

But in recent months, mercury data from fish, soil dug up behind the factory and now the river sediment are telling a different story: There is likely an ongoing mercury source and the mill property is it, or near it.

It is a story that government officials are finally listening to. In addition to the provincial commitment to clean the river, the Prime Ministers Office told the Star it would help deal with the mercury problem “once and for all.”

Though the province received a draft of the report in early February, it is not clear how much it factored into the Feb. 13 announcement that the province was committed to cleaning up the mercury.

In an email to the Star Monday, environment ministry spokesperson Gary Wheeler said the province was already working with the current property owner and the First Nations to conduct a comprehensive mercury contamination assessment at the Dryden mill site.

“If the Dryden mill site is an ongoing source of mercury, we will ensure appropriate measures are taken to stop further mercury from entering the river,” Wheeler said.

This historic commitment follows a Star investigation that since May has probed the impact of the poisoning and decades-long lack of action by government. It was made after the Star and volunteers from an environmental group called Earthroots found mercury-contaminated soil behind the Dryden mill.

This soil was found in an area identified by Kas Glowacki, a former mill worker who told the Star that in 1972 he was part of a crew that “haphazardly” buried drums filled with mercury behind the old mill.

The new research — conducted by Rudd and his team — was funded by the province, which has been under increasing pressure to deal with the mercury that has sickened the people of Grassy Narrows and nearby Whitedog. Rudd and the team of scientists he worked with was picked by and reports to Grassy Narrows leadership.

Another Star story, published in November, revealed the fish the people are eating are the most mercury-contaminated in the province.

The mercury found by the scientists is what they suspect is “legacy” mercury — that is, mercury used in production decades ago that spilled onto the property and seeped into groundwater, said Rudd.

The mill property needs to be carefully examined to confirm that the mercury is coming from there, and if so, a pump-and-treat system should be installed to intercept the mercury and remove it from groundwater before it reaches the river, the report recommended.

“The source has to be found and stopped,” Rudd said. “Ontario has now committed to doing that.”

A Domtar spokesperson did not respond to questions from the Star. Earlier this month, the spokesperson told the Star that the company had volunteered to pay for some additional sampling by independent experts on mill property. Also, the spokesperson, aware the river sediment report would soon be released, said in mid February: “Understanding what is happening in the river’s sediment may help determine if there are any significant, historical sources of mercury that are contributing to ongoing exposure.”

Rudd and the team determined there are two likely sources of the mercury found in the riverbed:

• Legacy mercury that has leaked from the site of the old mill into the river — a scenario found at other North American industrial sites that once used mercury in production processes. The factory buildings that used mercury were called chlor-alkali plants.

• Mercury initially dumped in Dryden in the 1960s could have been trapped or concentrated in the river banks or sediment beds outside the plant and then released downstream over time during high flows or other disturbances.

Conducting tests that revealed the presence of a particular isotope in the sediment samples, the scientists confirmed that at least some of the mercury found in the riverbed last summer was relatively new to the sediment. In other words, it is likely coming from the mill property.

Another reason Rudd believes the mill property in Dryden is likely leaking mercury is that other North American plant remediations have shown that once mercury leaks are stopped, sediment cleans itself naturally within 45 years. It has been nearly 50 years in Dryden’s case, and the levels, the new report found, are still very high.

In the 1960s in Dryden, Rudd said, “some of the mercury may have spilled as commonly happened in these industrial situations, and it may have gone through the concrete floor, through cracks in the concrete, … or some of it may have been disposed of on-site and as a result of the spillages, the groundwater on what is now the Domtar site may have become contaminated.”

Exactly how mercury is reaching the river from the plant is unknown, though the report says it could be via groundwater flowing from the mill property or discharge leaking from abandoned sewer pipes that act as conduits for mercury-contaminated groundwater.

Once the source of the mercury leak has been found and stopped, Rudd and the team have recommended two techniques to clean the river. One involves injecting nitrate or oxygen into the bottom of lakes and the other puts clean sediment in the water so that it eventually settles on the bottom to dilute the mercury-contaminated sediment. This method of cleaning, called enhanced natural recovery, was also recommended by Ontario’s Environment Minister in 1984.

The government of the day chose instead to allow the river system to recover naturally.