Ontario’s environment minister is promising to clean up the river system near Grassy Narrows First Nation “to the satisfaction of the chief and the health of the people.”

The Star reported Tuesday that a comprehensive analysis of provincial fish data conducted by the University of Waterloo’s research chair in biology, Dr. Heidi Swanson, revealed that the walleye eaten by the people of Grassy Narrows are the most mercury-contaminated in the province.

Clay Lake and two other sites along the Wabigoon River with top mercury contamination readings are within 80 km downstream from the site of the former paper mill in Dryden, Ont., that dumped 10 tonnes of mercury into the river in the 1960s.

The mercury in an average meal of walleye from nearby Clay Lake is 15 times the daily tolerable intake limit for adults, and about 40 times the limit for women of child-bearing age, pregnant women and children, the Star found.

In the legislature Wednesday, Environment Minister Glen Murray compared the province’s ongoing efforts in Grassy Narrows to another underway north of Sudbury.

“We will hold the Grassy Narrows people no less important than the people of Gogama,” he said. The town’s residents and members of the Mattagami First Nation had been calling for additional cleanup of crude oil that spilled into the Makami River after a 2015 train derailment there.

As part of the effort in Grassy Narrows, Murray said, the province has earmarked $300,000 for testing of the local fish as well as another $300,000 to Grassy Narrows leaders to conduct their own studies. “We’re doing exactly what the chief and the First Nations wanted and asked for and we are fully funding it to the extent they asked for it,” Murray said.

In the legislature last week, NDP environment critic Peter Tabuns blasted the government for taking too long to release some of these funds. As a result, he said, scientists have lost time in the field.

An ongoing Star investigation — which began in June with a report about a retired labourer who said he was part of a small crew that “haphazardly” buried drums filled with salt and mercury in the early 1970s — has renewed concerns from residents, scientists and politicians that nothing has been done to clean up the still-contaminated area.

“Clay Lake and the Wabigoon River, where the good people of Grassy Narrows live, have the most mercury-contaminated fish in the province, and it’s the Liberal government’s own data that proves that,” said NDP MPP France Gélinas in the legislature Wednesday.

When asked by Gélinas if the site of the old Dryden mill is still a source of mercury to the Wabigoon River, Murray said Wednesday that the province has conducted “extensive” tests of the site and found “there are no barrels buried and there is no source.”

The Star has repeatedly asked for details of the barrel search and Wednesday a ministry spokesperson said two types of tests were performed to detect metal over a “larger physical landscape area than identified” by the former mill worker who told his story to the Star.

“When the community (of Grassy Narrows) has fully reviewed the results we will be able to share the information with you,” the spokesperson said.

In May, a group of environmental scientists released a report that says high mercury levels in fish and sediment near Grassy Narrows suggest an ongoing source of mercury in the system.

The scientists also put forward a plan to clean the river system.

While Murray said “the conditions in the river right now lend themselves to higher mercury levels,” he suggested additional mercury could be coming “long distance” from the U.S. and Asia.

In general, many factors can explain elevated fish mercury levels in various lakes and rivers in Ontario, such as the impact of coal-fired generating plants and other industries around the globe that emit mercury, which is then deposited in rain and snow. Climate, geology, water chemistry and other factors can also make some water bodies more sensitive to mercury than others.

“We have a much more complex situation than we imagined, and we are investing heavily to remediate it,” Murray said.