Habitat modelling reveals four times more juvenile fish are expected in Hazeltine Creek post-remediation efforts
Mount Polley Mining Corporation is pleased to report that fish populations are thriving at Mount Polley. Further, the current habitat of upper Hazeltine Creek is over 1.5 times more likely to spawn fish than the pre-breach habitat. A recent report prepared by Golder, Mount Polley’s Environmental Consultant, reveals that the fish population in Hazeltine Creek is increasing as a result of the remediation efforts made by the Mount Polley Habitat Remediation Working Group* since 2014. Computer modelling of the fish population projects that there could be up to four times more juvenile trout in Hazeltine Creek in 2031 than in 2014.
“By May 2015 the water in Hazeltine Creek 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,” stated Lee Nikl, Principal and Senior Environmental Scientist – Mine Water and Environment Group at Golder. “By late 2017, fish were let back into the creek.”
We expect there to be almost twice as many juvenile trout in Hazeltine Creek by 2022. The new report uncovers that this is an outcome of the remediated habitat features in the creek, as well as the unobstructed conditions for upstream passage of fish, which are expected to persist in the long term. The Habitat Remediation Working Group has been guiding and overseeing habitat remediation since 2014 and “the design objectives and the designs themselves are the outcome of collaborative design with the Habitat Remediation Working Group”, said Nikl. “The focus of the remediation effort at Mount Polley has been to repair and rehabilitate Hazeltine Creek so that it becomes a self-sustaining, productive fish habitat.” said Brian Kynoch, President of Imperial Metals.
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
The remediation of Hazeltine Creek has been planned and advanced through the direct collaboration of Mount Polley mine employees, government agencies, First Nations and their technical advisors. This collective is called the Habitat Remediation Working Group (HRWG).
Recently, members of Mount Polley mine, Golder Associates Ltd, FLNRO (Ministry of Forests, Lands, Natural Resource Operations and Rural Development) and the Xatśūll First Nation attended a September 2020 HRWG tour.
On the tour the HRWG inspected the construction of habitat features in Lower Hazeltine Creek. The group also inspected the weir and fish ladder at Polley Lake, the functioning spawning habitat in Upper Hazeltine Creek and the terrestrial plant growth in Polley Flats.
The group viewed all stages of remediation, from installation of habitat features to a remediated ecosystem in Upper Hazeltine Creek that is maturing into a self-sustaining landscape used by all manners of life forms.
Discussions on the tour included: • Local nursery plant sources; • Local contractors support in the remediation efforts; • Reflections on how far the remediation has advanced; • Reopening plans for the mine; • Plans for the continued use of the weir on Polley Lake for flood control and fish rearing in Hazeltine Creek until the plants in the terrestrial flood plain mature; and • In stream habitat features installed are potentially superior to those that existed pre-2014.
Below are some photos from the tour (September 2020).
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 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.
Katie: “My name is Katie McMahen. I was born and raised here in Williams Lake and I was a member of the environmental team here at Mount Polley for a number of years. Although it was a really devastating event, as scientists we want to learn what we can out of this work that’s going on and so we’re studying methods for restoring functioning forest ecosystems, methods for rehabilitating the soil, and trying to improve best practices, really. Since day one, we’ve been doing a ton of environmental monitoring and really prioritizing fixing up the creek.
“So I love the forest, and I love working and rehabilitating the forest, so some of the coolest work we’ve been doing is not just the replanting of trees, but trying to trying to create the right conditions for those trees to thrive. So, managing the tailings, doing some techniques to really make nice little sites for the trees to grow and so that they had the proper soil conditions.”
Gabriel: “My name is Gabriel Holmes, and I grew up in Likely, British Columbia, and I’m an environmental technician here, I’ve worked here since 2011. I’m really proud of reintroducing the fish into the creeks – there’s a whole bunch of things I could go on and on – but reintroducing fish into Hazeltine Creek was a real milestone, the success of the spawning last year of the rainbow trout and Hazeltine Creek, a real milestone. The vegetative communities that are developing in our terrestrial landscapes in riparian areas and then of course this year, seeing a number of sockeye salmon in Edney Creek. I’m really proud to see that occur because that’s one of our end goals that we were trying to accomplish and to see them utilizing the system today, it’s fantastic.”
Katie: “I’m super proud of the work that we’ve done here. One of the biggest challenges has just been the scale of the work that we’ve had to do, and so considering it’s only five years now since the breach, just the sheer amount of work that’s been done in those five years is amazing. When I look back it feels like way longer because I can’t believe how much we’ve done.
“We’ve really set a high precedent for what needs to happen following an incident like this and that the type of work that can be done and should be done to clean up sites. There’s a lot of information that needs to get out there about what what’s the actual environmental conditions and the fact that we have thriving rainbow trout in the creek and tons of wildlife and animals using the habitat that we’ve created. It’s going to take some years for everything to grow, but these ecosystems are well on their way to recovery.”