Tag: polley lake weir

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.