WILLIAMS LAKE - Testing continues on sediment samples and water-quality samples taken by Ministry of Environment staff.
Sediment samples from inside the tailings impoundment on Aug. 12, 2014, and outside the tailings impoundment at the breach on Aug. 12 and 15 exceed some B.C. standards and guidelines. However, they are consistent with baseline tailings samples taken from 2010-14.
For the sediment samples collected Aug. 12 and 15, 2014, the following were identified as exceeding standards and guidelines: copper, iron, manganese, arsenic, silver, selenium, and vanadium.
These results from within the immediate impact area suggest low but potentially significant arsenic and selenium concentrations in sediments. Although these are often found in rock and minerals in the natural environment, Interior Health will be monitoring these results for potential long term health risks.
The results reinforce the need for a long-term monitoring plan. The current “Do Not Use” order will remain in place on the impact zone. However, water sourced from outside of the impact zone is still considered safe to drink.
Residents continue to be advised by Interior Health that they should not be drinking cloudy water. If they notice increased turbidity, sediment, and/or a change in taste or odour, consider filtration and disinfection per normal water practice − see http://bit.ly/ihawater − or using alternate water sources.
Guidelines where exceedances were observed include:
- B.C.’s working sediment quality guidelines;
- the contaminated sites regulation sediment quality criteria; and
- the Canadian Environmental Quality guidelines (CCME) for the protection of environmental and human health.
Pre-breach tailings samples were collected as recently as May 31, 2014, and, along with the average baseline sample results from 2010-14, these pre-breach results show the same metals exceeding the same guidelines.
Test results from legal sediment samples taken Aug. 7 from an area not impacted by the breach - downstream of the mouth of Hazeltine Creek toward Raft Creek recreation site from the lake bottom (at 10m depth) - also exceed BC working sediment quality guidelines for nickel, chromium, copper and iron.
Areas where mines are located can often have elevated levels of metals, meaning naturally occurring metal concentrations are potentially much greater in this region than elsewhere in the province.
It is also important to note, these samples were analyzed for total metals that are bound to sediment and not dissolved metals in the water that are bioavailable to aquatic life. Long-term monitoring and testing is necessary to help better determine and understand any potential long-term impacts to aquatic life.
The Pollution Abatement Order issued to Mt. Polley Mining Corporation on Aug. 5, 2014, requires the company to undertake short- and long-term environmental impact assessments and implement a monitoring and remediation plan to address environmental impacts and report on progress against actions regularly.
A comprehensive environmental impact assessment and action plan has been submitted to the Ministry of Environment and will be released publicly once it receives ministry approval.
Water samples were also taken from Quesnel Lake on Aug. 16, 2014, by Ministry of Environment staff, targeting the sediment plume to help determine the worst case scenario for drinking water and aquatic life. Results do not reflect the water quality throughout the entire water column.
Samples were taken at the following locations and depths:
- Quesnel Lake at Hazeltine Creek confluence - 0.5 and 17.5 m depths
- Quesnel Lake at Hazeltine Creek’s new path - 0.5 and 7.5 m depths
All samples collected at the original confluence of Quesnel Lake and Hazeltine Creek were within federal and provincial drinking water guidelines. The flow out of Hazeltine Creek established a new path, slightly upstream in the new delta, where there were a few exceedances including turbidity, and total and dissolved aluminium.
Aluminium concentrations are generally higher in water bodies in this area. IH has assessed these results and have determined the water in the area is still safe to drink.
Test results from these locations and depths also meet all aquatic life guidelines with a few exceedances, including: copper, dissolved aluminium, turbidity and total suspended solids.
The sample collected at 7.5m from the Hazeltine Creek new path site was slightly grey and cloudy in appearance, which would correlate with the elevated turbidity and total suspended solids seen in the results. This sample likely captured the plume. Copper and dissolved aluminium results were also elevated at this depth.
All results and explanations are publically available on the Ministry of Environment’s dedicated Mount Polley site: http://www.env.gov.bc.ca/eemp/incidents/2014/mount-polley.htm
Ministry of Environment