Salmon

The Mount Polley spill could have an impact on the region’s salmon production but it currently remains a question.

The young salmon in the area and this year’s spawn may face what the Ministry of Environment called “adverse effects” after tests showed higher-than-allowed levels of copper and iron in water samples taken near the mouth of Hazeltine Creek and Raft Creek and from the Quesnel Lake bottom.

The Pacific Salmon Commission, a U.S.-Canada agency, said there are two primary issues: the impact on adult salmon returning to Quesnel Lake for spawning and young fish growing in the lake. “The spill could impact their survival and food supply,” the commission said, adding that there are still uncertainties pending the outcome of the investigations.

“The peak migration of sockeye into Quesnel Lake would not be expected until the first week of September,” it said. This time lag, combined with water quality tests “suggest that substantial impacts on adult sockeye returning this year are unlikely.”

The Ministry of Energy and Mines inspectors now at Mount Polley aren’t strangers there, having investigated a possible breach at a different part of the tailings pond on May 24. However, they determined then that there was no breach but that the height of the pond exceeded allowances.

The level was reduced by June 30, the ministry said. The water level was within about 1.5 ft of the crest, Dunbar says, and had to drop to about twice that much.

“This was done by draining the excess water into an unused pit,” he says. “It was known for some time that this was a 'net positive water balance' impoundment,” or one where there was too much water even after accounting for evaporation, loss and water returned to the concentrator where ore is ground to a slurry, he says.

Earlier, on April 18, the ministry issued an advisory to Mount Polley for bypassing authorized treatment works and allowing effluent overflow to move into a long ditch. It did not reach the creek.

Imperial’s mining crews have started building a temporary dike to prevent any more water flow from the pool, and have a scheduled Sept. 15 completion date, spokesman Steve Robertson says.