An investigation conducted by a British Columbia commission found that the provincial government had not violated public disclosure laws by withholding information on Mount Polley mine prior to its tailings impoundment dam breach last summer.

The report was put together by Information and Privacy Commissioner Elizabeth Denham and addresses complaints that the province had violated Canada’s Freedom of Information and Protection of Privacy Act.

On Aug. 4, 2014, the mine’s tailings pond wall ruptured and released 13.8 million cubic yards of metals-tainted effluent into the nearby lakes and river system. Waste materials released included arsenic, nickel and lead.

Following the breach, the B.C. government initiated three separate investigations to determine what went wrong, with an independent engineering review panel publishing its report in late January. The panel determined the breach was a result of failures in the design of its embankment. The design had not taken sub-glacial and pre-glacial geological environment into account, a mistake contributing to the slide of its foundation.

Two other investigations of the Mount Polley breach are ongoing, to determine whether charges will be laid for contraventions of the Mines Act and investigate possible breaches of the Environmental Management Act.

In compiling her own report, Denham explained she had examined ministries of Energy and Mine and Environment records from 2009 through the time of the breach, as well as records provided over the same time period by mine owner Imperial Metals and other contractors.

Denham determined a tension crack in the dam’s surface reported in 2010 “did not pose a risk to the public or to the environment” because of its situation. Similarly, reports in May 2014 of water levels at the dam in excess of safety requirements did not require public disclosure because steps were taken to mitigate the problem. Tailings were briefly diverted and the dam elevation was raised through June and July, shortly before the breach.

“The correspondence between ministry engineers indicated that in their opinion the situation was under control and the mitigation measures were acceptable,” her report concludes. “The documents reviewed by my office and by our engineering consultant in relation to this incident did not indicate that government had information about a risk of significant harm to the public or the environment.”

Denham points out that the review panel also reached the same conclusion. Her full report can be read online at https://www.oipc.bc.ca/investigation-reports/1814.

Repairs to Mount Polley’s tailings storage dam were completed in April, and the mine is expected to receive permitting for resuming operations this month.

The breach at Mount Polley heightened concerns among Southeast Alaskan and Canadian border communities, with residents and user groups worried about future water quality as half a dozen sizable mining projects develop near shared rivers.

Entering into full production last month, the Red Chris mine upstream of the Stikine River poses a particular dilemma for Wrangell and Petersburg, utilizing a similar, but larger, tailings containment dam than that at Mount Polley.

Red Chris is the sixth major B.C. mine to have started production since 2011, part of a broader push in the province to exploit its natural resources. The mine is anticipated to produce copper and gold at a milling rate of more than 33,000 tons per day over a 28-year project life.

Wrangell’s fishing and subsistence community relies heavily on the salmon which spawn in the Stikine each year, and activities at the mine could have a detrimental impact on the river system’s water quality.

An independent review conducted for the Tahltan Central Council and presented last October brought up problems with the mine’s proposed tailings management. Due to the mine’s scale, the report suggested a disaster there would “likely have a much more significant environmental impact than the Mount Polley failure.” It also laid out close to two dozen recommendations for the mine to lessen the risk of its impact on water quality, but those have not had an effect on Red Chris’ design.

What effect the Mount Polley disaster has had on fishing in the Fraser River system is still unclear. Water sampling by the province’s Ministry of Environment and the mine’s administrators is ongoing. While a drinking water ban for Quesnel Lake was lifted a little over a week after the breach, researchers are watching to see what effect lingering effluent may have on the river’s sockeye population.