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Big Bar landslide response information bulletin

October 2 2020

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Coho are passing the slide site unassisted

Coho have been observed migrating past the Big Bar landslide site without any assistance this week as water levels returned to near seasonal averages in the Fraser River. To date, more than 152,000 salmon have been detected at Churn Creek, upstream of the slide.

Regular stock assessment activities are ongoing as fish from a number of populations, including the Summer and Early Summer sockeye, are still arriving at the spawning grounds. With the end of the salmon migration approaching, an in-depth scientific evaluation of fish passage, spawning and survival data is now underway.

Update on fish monitoring

The fish wheel operations, led by the Gitxsan Watershed Authorities and St’at’imc Eco Resources, has been essential to the success of the radio tagging program, especially for coho. The weekly tagging target for coho is between 50 and 70. As of September 30, all 189 coho tagged to date were collected using the fish wheel.

Additionally, 388 sockeye and 337 chinook have been radio tagged as part of the program. These fish have been collected using various methodologies, including the fish wheel, angling and seining.

A recent data analysis assessed the flow levels that salmon were able to successfully pass the slide site in 2020. Preliminary results indicate that sockeye were able to navigate the slide site unimpeded at approximately 2,800 cubic metres per second (cms) compared to 1,800 cms in 2019. Meanwhile, chinook were able to do the same at 3,000 cms in 2020 compared to 2,400 cms in 2019. Salmon passage at higher flow levels is directly related to successful in-river work in winter 2020.

Enhancement program update

The Upper Fraser natal stream brood collection program is now complete. Under the continued leadership of the Upper Fraser Fisheries Conservation Alliance, these eggs are being incubated at the Quesnel River Research Centre (QRRC), a facility operated by the University of Northern BC. Most of the eggs will be moved to a DFO hatchery at a later date.

As a result of the unprecedented efforts by all involved, the 160,000 eggs collected from chinook this season have resulted in approximately 68,000 eggs containing an embryo (eyed eggs) following incubation at QRCC. These eggs have been sent to their respective facilities where they will be reared until ready for release in summer 2021.

The 240,000 eggs from Early Stuart sockeye and 19,500 from Bowron sockeye at the Cultus Lake Research Lab are currently being counted for eyed eggs before they are also moved to hatcheries.

Ongoing onsite operations

As summer turns to fall, storms and associated high winds are returning to the Big Bar landslide site. The inclement weather is once again challenging work at site, including helicopter operations, scaling and road upgrades.

Demobilization of the Whooshh Passage Portal™ is progressing. Slope stabilization also continues to ensure site safety.

Long-term planning underway

Over the last several months, the Big Bar Landslide Response team has been focused on the critical next steps for the 2021 migration season: to plan, evaluate and implement a permanent solution to restore fish passage at the slide site.

A key challenge to any work at the slide site is its remote location. The terrain is rough and conditions are further exacerbated by harsh weather, high winds, extreme temperatures and threats of flooding, wild fires and rock fall hazards. These conditions pose constant challenges to crews, as experienced by prime contractor Peter Kiewit Sons ULC (Kiewit), and First Nations and DFO crews earlier this year.

Despite these factors, extensive progress was made through the 2019-2020 winter construction season. Kiewit was successful in accessing the work site, clearing some of the debris, blasting boulders, widening the river channel, and constructing the “nature-like” fishway. This work has been instrumental in improving the flows through the canyon, allowing fish to move upstream at levels they were unable to navigate in 2019 and extending the migration windows during periods of high flows in 2020.

Following an analysis of the winter work results and preliminary 2020 migration data, there is now a better understanding of the scope of work required to implement sustainable passage for salmon at Big Bar.

An options analysis conducted earlier in the year recommended that a permanent fishway is the best long-term solution to provide certain and reliable fish passage at Big Bar in the shortest timeframe. A key consideration in this undertaking is that building a fishway at Big Bar is only possible during low water levels in the Fraser River – usually between November to March depending on the arrival of the freshet. This project is expected to take between two and three years to complete.

The Big Bar Landslide Response Joint Executive Steering Committee, the First Nations Leadership Panel and the technical response team jointly recognize the importance of this work to ensure the long-term survival of vulnerable fish populations, particularly the Early Stuart sockeye and Early Spring chinook. Resolving the blockage is a massive, extremely challenging undertaking and will take considerable resources to address adequately.

Due to the urgency to begin construction, DFO is working actively with Public Services and Procurement Canada to develop an approach for the upcoming winter work season and beyond, which includes planning, design work and contracting. Further information on these planning efforts will be available in future issues.

Current images of work being done at the landslide site

Picture of the landslide site
Fish wheel will be in use until late October, when the majority of coho are expected to have passed through Lillooet. Click to enlarge.
Picture of the landslide site
Crews are applying radio tags to coho collected using the fish wheel. Click to enlarge.
Picture of the landslide site
Demobilization of the Whooshh™ system is progressing; the fish transport tubes are being disconnected from the Accelerator component. Click to enlarge.
Picture of the landslide site
Aerial view of the Big Bar landslide site in late September, where the Whooshh™ is being demobilized. Click to enlarge.

Additional images of the work underway as part of our response efforts can be seen on the Government of BC’s Flickr channel.

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