WILLIAMS LAKE – Water samples taken by Ministry of Environment staff from the southeast corner of Polley Lake on Aug. 7 and 8, 2014, have been tested and are very close to historical levels taken prior to the Aug. 4, 2014, tailings pond breach.
Results indicate the concentrations of most of the parameters were below both B.C. and Health Canada Drinking Water Guidelines at these sites with slight exceedances of pH and aluminium.
Neither of these exceedances presents any risk of adverse health effects and are consistent with water quality results from Polley Lake since the late 1980s. These results corroborate similar tests taken from the shore of Polley Lake by Imperial Metals.
As a result of this latest testing, Interior Health (IH) has further rescinded its water use ban. A water ban will remain indefinitely for the impact zone directly affected by the breach which includes, Polley Lake, Hazeltine Creek, and on Quesnel Lake, but only the area within 100 metres of the shoreline plume where Hazeltine Creek runs into Quesnel Lake. For more information and a detailed map, please visit:
Additionally, water samples taken on Aug. 7, 2014, from three locations in Quesnel Lake and along Quesnel River have been tested with most of the parameters below both provincial and federal drinking water guidelines.
The exception was a sample taken from a localized area with a visible suspended sediment plume between Hazeltine Creek and Raft Creek. This sample was tested as a worst case scenario. Results showed slight exceedances of phosphorus and aluminium for drinking water and exceedances of copper, chromium, phosphorus and aluminium for aquatic life guidelines.
These elevated levels would be expected near an aluminium/copper mine. Additional samples will be collected from Quesnel Lake, as this was the worst case sample and is not representative of the general quality of Quesnel Lake.
Sampling will take place in safely accessible locations for the foreseeable future. Test results will be shared with local First Nations, First Nations Health Authority (FNHA), IH, and the Cariboo Regional District.
The Ministry of Environment has also collected Rainbow Trout and Lake Trout tissue samples from Quesnel Lake on Aug. 8, 9 and 10, 2014, for tissue analysis and the results are expected within two-to-three weeks; however, efforts are being made to expedite the testing.
The ministry has also taken sediment and plankton samples and are awaiting lab results, expected later this week, to contribute to an assessment of any potential impact to fish and aquatic life. Generally, bio-accumulation of contaminants in fish occurs over a longer exposure time than a few days.
The tailings liquid initially released from the impoundment moved very quickly through the system and was diluted greatly by the water in the lake, the Quesnel River and ultimately the Fraser River. As such, fish exposure was limited and not long enough for uptake into tissues. Combined with the fact that the water in Quesnel Lake meets drinking water guidelines, it is unlikely there will have been any short-term effects on fish in Quesnel Lake or downstream as a result of this event.
The only reported dead fish is a rainbow trout. It was brought to the ministry’s attention on Aug. 6, 2014, following the public meeting in Likely. It was collected by researchers with the University of Northern BC. Ministry of Environment boat crews have been on the water since Aug. 4, 2014, and they have not found nor received any other dead fish.
If any dead salmon are found in the Fraser River it is likely a result of temperature effects and not contamination from the tailings pond breach. This is not unexpected due to the summer climate in the region.
Based on this information, IH and its Regional Medical Health Officer are confident any fish caught for human consumption beyond the immediate sediment deposit zone are safe to eat. This includes fish from the unaffected area of Quesnel Lake, the Quesnel River, and the Fraser River.
At the request of First Nations, FNHA are supporting salmon sampling on an interim basis. Collection of salmon will be coordinated with First Nation fisheries departments. A two-to three day turnaround time is anticipated following the arrival to the lab. More information on salmon sampling will be posted at
Once sediment sample results are available, the ministry will be able to determine if there is any risk posed by the tailings solids. Long-term monitoring of sediments and identification of any contaminants found in sediment will continue as part of longer term monitoring.
The ministry continues to urge anyone who sees dead fish to report it immediately to the ministry through the RAPP line (1 877 952-7277) or to the Emergency Operation Centre in Williams Lake (250 392-9675).
More information regarding response to the Mount Polley mine incident can be viewed here:
Ministry of Environment
Page last modified: October 30, 2018 09:50:58 PDT