Environmental monitoring programs and closure research projects at Mount
Polley mine site continue as planned. Remediation
construction at the lower Hazeltine Creek and Edney Creek began this summer.
Mount Polley staff, with assistance from Golder Associates Ltd., have begun development
of the 2022 Water Management Plan.
include regular water quality and toxicity sampling at:
water treatment plant (WTP)
surface waters of Polley Lake, Bootjack Lake, Hazeltine
Creek, Edney Creek & Quesnel Lake
mine contact waters including groundwater &
mine seepage with flow rates
Regular inspections of
all critical ditches, sumps, ponds, pumping systems and pipelines.
Ongoing surveys and
spawning activity in Hazeltine & Edney Creeks
remediated terrestrial habitats; vegetation growth, nesting sites and wildlife usage
aquatic habitats; fish population & tissue, zooplankton, phytoplankton, benthic invertebrates and sediments in Bootjack, Polley & Quesnel Lakes
dilution modelling of the Quesnel Lake discharge
semi-passive and passive water treatment options for closure which include a constructed wetland treatment system pilot study and a saturated rock fill bench scale test
Lately we have received questions about the water quality at Quesnel Lake, so here are a few Q&A’s which address this subject.
First, what it means to conduct remediation?
According to the BC Environmental Management Act, “remediation” means action to eliminate, limit, correct, counteract, mitigate or remove any contaminant or the adverse effects on the environment or human health of any contaminant.
At Mount Polley, using the results of the detailed site investigations, and the human healthand ecological risk assessments, the goal of the mine’s environmental remediation work is to repair and rehabilitate the areas impacted by the tailings spill such that they are on a path to self-sustaining ecological processes that result in productive and connected habitats for aquatic and terrestrial species.
As the impacts of the spill were determined to be primarily physical and not chemical, this has meant that the focus of the work has been on repairing and rebuilding habitats.
Where can I find data about the water quality in Quesnel Lake?
The BC government website hosts an interactive mapof surface water monitoring sites in the Province which gives access to results of water sampling and analyses, including Quesnel Lake and other surface water sites around the area of the mine.
Why was the decision made to leave the tailings at the bottom of Quesnel Lake?
Research and monitoring of the physical and chemical stability of the tailings on the bottom of Quesnel Lake indicate that they are not causing pollution and studies of the bottom-dwelling (benthic) organisms have shown that they are slowly recolonizing the lake bottom as native sediment slowly deposits on top of the organic-poor tailings, bringing organic matter to the lake floor.
After completing a Net Environmental Benefit (NEB) assessment, experts recommended that the best approach for remediation of the tailings in Quesnel Lake was to leave them alone and cause no further disturbance.
The experts determined that any attempt to remove the tailings could significantly disrupt the present ecosystem and set back the progress that had already occurred.
Remediation at Mount Polley is all about creating the conditions for successful natural recovery, and not doing more damage.
The following provides some comments from Mount Polley Mining Corporation (MPMC) on the Hamilton paper (Hamilton, et al. 2020) regarding Quesnel Lake in relation to the TSF Breach at Mount Polley. The note is divided into general comments, specific comments, and then provides an update on Quesnel Lake water quality, and some key observations from recent sediment and aquatic life monitoring, which support the MPMC comments on the paper. This is not a comprehensive review of the paper.
The Hamilton paper provides a summary of a considerable amount of monitoring data collected in Quesnel Lake, including from automated moorings. (Note: MPMC contributed to this research through the purchase of a number of new instruments for the moorings in the fall of 2014.)
The paper focusses on seasonal observations of a slight increase in turbidity deep in the West Basin, and on physical lake dynamics. It also introduces some hypotheses regarding new mechanisms of lake water movement. MPMC is pleased to have contributed to this enhanced understanding of water movements in large lakes.
However, we are concerned that important monitoring data, available on our web site or directly from MPMC or our consultants, was not referred to or incorporated into interpretations made in the Hamilton paper. The use of information that is readily available from MPMC’s web site or directly from MPMC or its consultants would have helped address some of the authors’ concerns, particularly about future impacts to aquatic life and contamination.
Unfortunately, the paper does not include data from the mine’s monitoring nor any other data on these topics. The paper contains a number of interesting scientific observations, but these do not necessarily indicate an environmentally consequential measurement.
Specific Comments on the Hamilton et al (2020) paper:
Mount Polley’s monitoring data indicates that contaminant levels in Quesnel Lake are not elevated. The paper identifies a small turbidity signal at depth, but turbidity does not necessarily indicate contamination. (See below for a description of “what is turbidity”.)
Hamilton et al’s data from 2015 to 2017 indicate a significant decline in the seasonal turbidity signal they measured since the spill in 2014. This observation agrees with MPMC’s monitoring data.
The turbidity values measured by both MPMC and Hamilton et al are belowBC water quality guidelines, which are based on a 30-day average. (The BC Guidelines allow for increases to 10 NTU for short durations.)
There are no data presented in the paper from 2018, 2019 or 2020. This is a significant shortcoming of the paper being able to speak to the current situation, or to future impacts. MPMC has monitoring data for 2018 to 2020 for a number of sites in the lake that the researchers could have used to assess trends after 2017 for both water quality and aquatic ecosystem health.
The levels of turbidity measured by Hamilton et al deep in the West Basin are quite low. (Between winter 2015 and winter 2017 they range from highs of approximately 2.3 FTU, to less than 0.5 FTU.) Turbidity is a measure of “cloudiness” due to particulates in water, however, the levels of turbidity being measured in this paper are not easily seen with the naked eye (in other words, instruments are required to measure these levels).
The paper provides background (pre-spill) data that indicate that the turbidity signal they observed at depth is at or below the level of natural turbidity events in the West Basin in the past (for example, a plume from the Horsefly River in May 2008 increased the turbidity in surface water of the West Basin to greater than 2.0 FTU as seen in Figure 3 in the paper). Natural turbidity events, such as are associated with heavy rains, spring freshet (snowmelt) or high-water floods, can generate similar or higher levels of turbidity. This summer, high creek and river levels generated muddy, debris-laden, flows into Quesnel Lake.
The paper postulates suspension of material from an unconsolidated layer of particulates at or near the bottom of the lake. While the unconsolidated layer identified in core samples is interesting, there is no data in the paper on what the particulates are that make up this layer. MPMC has reached out to the authors with an offer to either do this work on their samples or contribute funding to fill this information gap. Note that the paper does not say that tailings are resuspending off the bottom of the lake. Note also that MPMC sediment monitoring has observed natural material, with organic carbon, settling into sediment traps placed on the bottom of Quesnel Lake and presumably covering tailings.
There is no data in the paper that indicates that the particulates associated with their turbidity signal are contaminated with any metals or chemicals of concern. MPMC’s monitoring shows that water quality in Quesnel Lake is below the BC Water Quality Guidelines, except during spring freshet when area creeks naturally discharge elevated turbidity and copper.
MPMC supports the Hamilton et al observation of no visible colour change in the lake since 2014. This confirms MPMC’s observations.
Mount Polley’s water discharge is permitted by the BC Government and is within strict permit guidelines that are protective of sensitive aquatic life. The paper noted a small increase in specific conductance associated with the MPMC treated water discharge in 2016, but also noted that there was no turbidity signal associated with this discharge. These data agree with Mount Polley’s monitoring data. MPMC’s monitoring continues to show that water quality in Quesnel Lake is below the BC Water Quality Guidelines except during spring freshet when area creeks naturally discharge elevated turbidity and copper and when MPMC are typically not discharging because of restrictive permit requirements.
The paper expresses concern about the potential resuspension of spill material from Quesnel Lake and its impacts on juvenile sockeye salmon, while not including data DFO collected on juvenile salmon in the West Basin in 2014, the year of the spill, nor acknowledging that the 2014 juveniles were the cohort that “returned in droves” to the Quesnel Lake watershed in 2018. This juvenile salmon cohort would presumably have been the most impacted as they were feeding in Quesnel Lake the year of the spill, yet there has been no indication that the tailings spill had a deleterious effect on their feeding or their returns four years later.
Mount Polley is very pleased to see that the paper noted that the MPMC remediation of Hazeltine Creek“reduced sediment loads as no turbidity signal >0.2 FTU above background was detected near its mouth from 2015 through 2017”.
Quesnel Lake Water Quality
There is no evidence of pollution being
caused in Quesnel Lake related to the Mount Polley spill. This is affirmed by MPMC monitoring and by
BC ENV comments to the MPMC’s Public Liaison Committee.
Results of the Comprehensive Environmental
Monitoring Program (CEMP) – Sediment and Aquatic Life (Minnow, March 2020) monitoring
using DGT instruments in Quesnel Lake indicate:
concentrations in 2019 “were well below [freshwater aquatic life] effects
there is “strong evidence of … post-depositional
stability of the sediments impacted by the breach”, i.e. there is no
indication that metals are leaching out of tailings into the water in Quesnel
analytes in 2019 were all below BCWQG’s”, i.e. all metals analyzed using the
DGT’s were below the BC Water Quality Guideline thresholds for protection of
freshwater aquatic life.
The definition of Turbidity is the cloudiness or haziness of
a fluid caused by suspended solids that are usually invisible to the naked eye.
The measurement of Turbidity is an important test when trying to determine the
quality of water. It is an aggregate optical property of the water and does not
identify individual substances; it just says something is there. Water almost
always contains suspended solids that consist of many different particles of
varying sizes. Some of the particles are large enough and heavy enough to
eventually settle to the bottom of a container if a sample is left standing
(these are the settleable solids). The smaller particles will only settle
slowly, if at all (these are the colloidal solids). It’s these particles that
cause the water to look turbid.
Hamilton, A. K., B. E. Laval, E. L. Petticrew, S. J.
Albers, M. Allchin, S. A. Baldwin, E. C. Carmack, et al. 2020. “Seasonal
Turbidity Linked to Physical Dynamics in a Deep Lake Following the Catastrophic
2014 Mount Polley Mine Tailings Spill.” Water Resources Research
56. doi:https://doi.org/ 10.1029/2019WR025790.
In 2018 a milestone was celebrated by the Mount Polley Environmental Team (MPET) when the efforts of the remediation work rebuilding Hazeltine Creek witnessed the return of Rainbow Trout, Redside Shiners and Long Nose Suckers to the rebuilt part of the creek.
After the August 2014 tailings spill, fish from Polley Lake were prevented from entering Hazeltine Creek by fish fences above the Polley Lake Weir, while the habitat underwent reconstruction. During the winter of 2014-2015, the creek channel was cleaned up, tailings and debris removed, and a new Hazeltine Creek channel was built and rocked-in.
In April 2015, the Habitat
Remediation Working Group (HRWG*), including the T’exelc
First Nation (Williams Lake First Nation) and Xatśūll First Nation (Soda Creek
Indian Band) and their consultants, and Mount Polley Mining Corporation
(MPMC) representatives and their consultants (Envirowest and Golder), began discussing
options for constructing new fish habitat in upper Hazeltine Creek, and
requirements MPMC would need to meet in order for fish to be allowed to return
to the creek.
*HRWG also includes representatives of the federal
Department of Fisheries and Oceans, the provincial Ministry of Environment, and
the provincial Ministry of Forest Lands and Natural Resource Operations, both
water stewardship and fisheries sections.
Mount Polley employees, consultants, contractors, First Nations and community partners began ecological remediation work on Hazeltine Creek in 2015. By May 2015 the water in Hazeltine was running clear, and the bugs (invertebrates that provide food for fish) were starting to grow in the creek, so it was decided that the installation of new fish habitat could begin and this work started in 2016.
HRWG members looked at historical records to
determine what the local conditions were before the spill, and remediation
planning was based on that information. The planning was also constrained by the
configuration of the constructed rocked-in channel. The group agreed to a field
fit approach for the remediation. Conceptual designs were developed by Mount
Polley and their consultants, and the plans were reviewed by the HRWG.
The design approach was to naturalize the rocked-in channel by adding sinuosity (curves and bends), building a sequence of pools, riffles and weirs, and installing boulders, large woody debris and gravel at the bottom of the creek, to provide appropriate spawning and rearing habitat for the fish known to have used upper Hazeltine Creek before the spill, particularly Rainbow Trout, an important species in Polley Lake.
After two years of habitat construction (2016-2017)
approximately 2.5 km of spawning and rearing habitat was completed in the upper
part of Hazeltine creek from the outlet of Polley Lake to the Gavin Lake Road
Bridge. In late 2017, the MPET believed conditions were right to let the fish
back into the creek. There was habitat, flowing water, and food, and the water
quality met aquatic guidelines.
In December 2017, the HRWG began
detailed discussions on the approach to allowing the Rainbow Trout back into
Hazeltine Creek. Discussion included requirements for fish monitoring, water
quality, sediment quality, habitat quality and quantity, Polley Lake access and
egress etc, and the permits and licenses that Mount Polley would have to apply
for and comply with from the Ministry of Forests, Lands, Natural Resource
Operations and Rural Development Water Stewardship Group.
In March 2018, new fish fences were
installed in Hazeltine Creek approximately 2.6 km from the outlet of Polley
Lake to prevent fish from going further downstream than the area where habitat
reconstruction have been completed. On April 26, 2018, the fish fences at the
outlet of Polley Lake to Hazeltine Creek were removed and the Rainbow Trout
once again had access to the first 2.6 km of upper Hazeltine Creek.
Note: the lower part of Hazeltine Creek includes a
steep rock canyon that is a natural barrier preventing Quesnel Lake fish from
entering middle and upper Hazeltine Creek and Polley Lake. However, in the
natural creek system, fish from Polley Lake can be swept down the creek into
Quesnel Lake once all the fish habitat reconstruction is completed and fish
fences are removed.
In addition to ingress into Hazeltine Creek, the fish also needed to be able to return to Polley Lake. This required that a fishway (ladder) be built for the fish to bypass the Polley Lake Weir water control structure. An engineered fishway was installed by Mount Polley maintenance staff at the Polley Lake weir and the flows are monitored to properly maintain water levels for fish passage. The fishway was designed so the flow can be adapted to seasonal changes.
Fish monitoring was intense in 2018. MPET worked
with Minnow Environmental conducting weekly surveys of the fish populations to track
the 2018 spawn and fish activity. The surveys included counting fish at
established monitoring stations and pools, and observing how the fish used the
creek (i.e. seeking shelter under woody debris or behind boulders). Temperature
data and dissolved oxygen levels were also monitored in Hazeltine Creek.
Results of the 2018 Hazeltine Creek fish re-introduction were very impressive. Fish monitors estimated almost 5,000 Rainbow Trout accessed the creek to spawn in spring 2018. The spawn was successful. A spawning survey in July 2018 observed over 18,600 Rainbow Trout in upper Hazeltine Creek, the majority being from the 2018 spawn.
The area around Likely has a long and fascinating
history of placer mining. Placer mining refers to mining materials (mostly
gold) deposited in ancient stream beds that are still largely unconsolidated (i.e.
relatively loose materials).
Some of the earliest gold discoveries in the area were made in 1859, one in the Horsefly River, and one in the Dancing Bill Gulch. The latter became known as the China Pit and then the Bullion Pit, and is located just downstream of Likely on the west side of the Quesnel River. The Bullion Pit is now a local historic site with a public walking trail.
Placer gold was also discovered near the mouth of
Keithley Creek on the Cariboo River about 12 km upstream from Quesnel Forks in
July 1860. Other significant discoveries were subsequently made just 4 km south
of Likely on Cedar Creek, and in Quesnel River itself.
In 1897, the Golden River Canal Co. decided to build a dam across the Quesnel River at the outlet from Quesnel Lake in order to block the river and be able to work the gravels from the bottom of the river. The tent town that developed on the site was known as ‘Quesnel Dam’. In 1920, the dam was dynamited and the remnants of the dam can be seen just north of the Likely Bridge in Likely. After the removal of the dam, the residents decided to rename the town ‘Likely’ after a local prospector, John Likely.
The Bullion Pit ulimately became a very significant gold producer in the area. BC Minfile report number 093A 025 states that “In 1897, the Consolidated Hydraulic Mining Company commenced full scale operations and between 1898 and 1902, the company processed 5,912,700 cubic metres of mixed materials, recovering 1,402,316 grams of gold at a recoverable grade of 0.132 grams per tonne gold… Estimations indicate that a total of 200 million tonnes of material were removed by hydraulic methods and 5.463 million grams (175,644 ounces) of gold were produced.” Indications are that much of this material was discharged directly into the Quesnel River.
The shortage of water in the early 1900s led the operators of the Bullion Pit to construct a number of water control and diversion works on local streams and lakes to gather water for the hydraulic operations at the pit. Photos from the BC archives, including ones featured in the TV program “Gold Trails and Ghost Towns – The Bullion Pit episode”, document weirs and diversion ditches built on Polley Lake and Hazeltine Creek and other creeks in the area.
This Facebook page gives regular updates on the areas in BC that were part of the mine’s early gold mining history.
Many placer mines continue to operate in the area around Likely, including near Quesnel Forks. Quesnel Forks is a restored ghost town located 12 km outside of Likely with a rich mining history and is also worth a visit. It is situated at the point where Cariboo River meets the Quesnel River, and features a beautiful campground and a number of restored and partially restored old buildings.
Mount Polley takes water quality very seriously. Extensive monitoring is evidencing the effectiveness of the remediation and site water management programs undertaken by Mount Polley.
How is water quality monitored in Polley and Quesnel Lakes to ensure proper environmental monitoring is being carried out?
Mount Polley follows the BC-ENV approved Comprehensive Environmental Monitoring Plan. The results for all our monitoring sites are published in the publicly available Annual Environmental and Reclamation Reports.
Polley Lake water met all BC Water Quality Guidelines for aquatic life parameters in 2019 with the exception of phosphorus, which was elevated even prior to mining. As Polley Lake is immediately adjacent to the mine site, this indicates the mine is doing a very good job of capturing and controlling run-off.
A number of sites are monitored in Quesnel Lake, and in 2019 there were no exceedances of acute BC Water Quality Guidelines.
At one monitoring site in Quesnel Lake, there was one minor copper exceedance of chronic BC Water Quality Guidelines in 2019, but as copper is also naturally occurring in the native soils and sediments around Quesnel Lake, and there are a number of creeks that empty into the lake near this sample site, it is difficult to know if this exceedance was natural or related to the mine.
We often get asked if we continue to discharge into Polley Lake or Quesnel Lake?
The mine discharges mine site water, that meets strict permit limits, through diffusers at depth into Quesnel Lake. This water is the only substance the mine is discharging to Quesnel Lake. The mine does not discharge water into Polley Lake.
Mount Polley discharges only mine site water that meets strict Environmental Management Act (EMA) permit guidelines.
treated by a water treatment plant, when needed to meet permit requirements, before being released into Quesnel Lake. The water going into the treatment plant (influent) is monitored on an ongoing basis, and the treated water leaving the plant (effluent) is sampled regularly for analysis. Not all water at Mount Polley requires treatment to meet EMA permit water quality guidelines before discharge, and in the past, water that was simply stored in Springer Pit was found suitable for passive discharge.
The lake water quality is also routinely monitored and sampled regularly as part of the mine’s Comprehensive Environmental Monitoring Plan.
Continued monitoring data confirm that remediation efforts are effective.
Currently, there are no indications in the monitoring data that the water discharged from Mount Polley is having any negative effects on Quesnel Lake water quality or aquatic life.
If you are interested in looking at water quality data collected on surface water in the area around the Mount Polley mine, in addition to data in the mine’s annual reports, results are available through the BC Government Surface Water Monitoring Sites Interactive Map.
The remediation effort at Mount Polley is ongoing; however, we are very proud of the major milestones that have been completed to-date.
Repair of lower Edney Creek, re-establishment of link to Quesnel Lake and installation of new fish habitat for spawners from Quesnel Lake, completed in spring 2015, with evidence of successful spawning by Interior Coho, Kokanee and Sockeye Salmon.
Completion of construction of a new Hazeltine Creek channel in May 2015, to control erosion and provide base for remediation of the creek itself and the creek valley.
Ongoing planting of native trees and shrubs in the riparian and upland areas along the creek, now totally more than 600,000 trees and shrubs planted.
Installation of over 6 kilometres of new fish spawning and rearing habitat in upper to middle Hazeltine Creek. Evidence of successful 2018 and 2019 Rainbow trout spawning in upper Hazeltine Creek.
Clean-up and repair of 400 metres of Quesnel Lake shoreline, including placement of new fish spawning gravels.
Re-establishment of wetlands in the Polley Flats area adjacent to the repaired TSF.
There has been recent speculation about whether or not Mount
Polley is dumping waste into Quesnel Lake. In short, the answer is no. Current treatment of water at Mount Polley,
including the dilution zone at depth in Quesnel Lake, ensures water released
into Quesnel Lake is in line with BC and Canadian water quality standards.
Mount Polley discharges only treated mine site water that meets strict
Environmental Management Act (EMA) permit guidelines.
All mine site water is collected and is
treated by a Veolia ACTIFLO™ water treatment plant before it is released into
Quesnel Lake. (see veoliawatertech.com
for more information on their treatment systems and how they work.) The water
going into the WTP (influent) is monitored on an ongoing basis (measurements of
turbidity every 15 seconds) and the treated water leaving the plant (effluent)
is sampled regularly for analysis. The lake water quality is also routinely
monitored and sampled regularly as part of the mine’s Comprehensive
Environmental Monitoring Plan.
The following are facts that explore, in more detail, the
discharge from Mount Polley into Quesnel Lake. We hope this information provides
factual clarity about Mount Polley’s approved activities.
Is Mount Polley’s discharge having negative effects on Quesnel Lake?
are no indications in the monitoring data that the Mount Polley discharge is
having any negative effects on Quesnel Lake water quality. If you are
interested in looking at some of the water quality data that has been collected
on surface water in the area around the Mount Polley Mine, the results are
available through the BC
Government Surface Water Monitoring Sites Interactive Map
Is the water in Quesnel Lake contaminated? Is it safe to drink?
At this time, there are
no indications of contamination of Quesnel Lake water from the Mount Polley
spill. The mine, and the Ministry of Environment and Environment Canada,
continue to monitor Quesnel Lake. With the exception of natural causes, the
lake does not exceed environmental guidelines for any of the constituents of
concern that are found in the Mount Polley tailings.
As early as August 12, 2014, BC’s Interior Health
Authority (IHA) rescinded all water use restrictions from Quesnel Lake
(including for “drinking water, personal use, fishing, swimming and
recreational purposes”), except for the immediate impact zone where
Hazeltine Creek entered Quesnel Lake. The IHA notice also stated that “Interior
Health has no reason to believe that this water was ever exposed to unsafe
levels of contaminants from the mine breach. As a result, flushing and testing
of individual water supply systems is not considered necessary.”
All water use
restrictions were fully rescinded July 13, 2015. (Note: IHA always
advises that surface water be treated for pathogens prior to use/consumption.)
How much is the mine discharging into Quesnel Lake?
Management Act permit annual average authorized discharge rate is 29,000 cubic
meters per day. The actual discharge rate depends upon the rainfall experienced
at site which varies from year to year. In 2019, the annual average discharge
rate has been 14,883 cubic meters per day, significantly less than the mine’s
A lot has been written about the Mount Polley spill of 2014, though not so much about the remediation efforts which have been quietly underway for years to great effect. Mount Polley recovery and remediation continues. So far, over $70 million has been invested to make things right at the site and the affected areas. Let’s put Mount Polley into perspective. Local habitats are being restored. Fish spawning habitats have helped repopulate rainbow trout populations in Quesnel lake and Hazeltine Creek. The fish are biting are Polley lake!
Additionally, the project has been one that has followed scientific best practices. The Mount Polley remediation effort has restored vegegative coverage in the affected areas and is seeing local wildlife thrive at the site. The project has been carried out in coordination of Mount Polley Remediation staff along with First Nations partners.
Above all, responsible resource development means setting things right in the rare instances they go wrong. We’re proud of the work that has been done and we’re showing the world that Canada leads in taking responsibility and in developing remediation practices. Truly, Mount Polley recovery and remediation means no less than just that.
Indeed, Canada has a rich traditional of resource development and environmental stewardship. We hope to maintain that legacy and the work accomplished at Mount Polley reflects commitment to that ideal.
We’d like to highlight an article that adds much needed perspective. Dr. Lyn Anglin has written about the remediation efforts at Mount Polley. Dr. Anglin was President and CEO of Geoscience BC. She was the Chief Science Officer and VP Environmental Affairs at Imperial Metals until she retired in 2018. Dr. Anglin was also on the Advisory Council at Resource Works.