Site Recovery Operations
Continue to monitor fish passage to gauge success.
- Hydroacoustic monitoring is being used to estimate the passage success rate for individual fish of selected species, size and sex. Monitoring stations have been established at both Big Bar and Churn Creek. Currently, these stations have been removed due to rising water levels. (Re-establish sites in the future?)
- Radio tagging is used to monitor fish migration through the landslide. These tags allow scientists to determine how many fish are able to migrate past the slide either naturally, or having been transported. (or though intervention?)
Establishing a natural fish passage
- At the slide site, water flow has reached up to 2,900 m3/s (cubic metres per second) at various times, which is very high. Due to high water flow salmon have not been able to move upriver as the current is too strong.
- Rock manipulation techniques are being used to mitigate the landslide with scaling crews working to move rock from the bank, as well as from the rock face, and strategically placing it in the river bed in order to change the water movement. This altering of the rock landscape is intended to change water flow and velocity patterns, in hopes of creating a passage for the fish to move past the obstruction unassisted.
Fish transport above slide site
- Crews made up of BCWS and DFO personnel have established multiple seining sites downstream of the slide site. Seining is a technique in which fish are trapped in nets and collected from shore.
- Once caught in sein nets, fish are then transferred into oxygenated transport tanks. The tanks full of salmon are then flown by helicopter to an established site above the slide and released into the river so they may continue their migration.
- Personnel have been able to move more than 1000 salmon per day as transport capacity continues to increase. These operations remain ongoing daily as conditions allow.
- 177 Early Stuart Sockeye have been captured and transported to a rearing facility at the Cultus Lake Salmon Lab in Chilliwack. The purpose of this is to preserve some portion of this years class for the Early Stuart population. The eggs harvested from these Early Stuarts could yield up to 300,000 fry.
- For more information see the Pilot Salmon Enhancement Information Bulletin.
Install a prefabricated temporary fishway structure or a combination of the two.
- A fish wheel has been assembled on site and is undergoing testing. Once implemented, the fish wheel will be used to increase the capacity of fish capture and transport operations. Fish Wheels are often used by First Nations river fisheries.
- A fish ladder has also been assembled and will be implemented when and if conditions allow. A fish ladder is an artificial structure which functions by providing a series of water “steps” that fish are able to leap up, thus passing the obstruction and continuing migration.
- A pescalator has been delivered to the Incident Command Post in Lillooet and will be assessed for operational feasibility. This prefabricated fish transport device is placed on an angle and gently turns to move fish.
Each of these options come with potential benefits, risks and possible consequences and are being comprehensively assessed.
The Environmental Unit continues to receive offers of support and suggestions for landslide mitigation response from other agencies, private companies, and concerned individuals. All viable options are jointly discussed between the First Nations Leadership Panel, the Unified Command Incident Management team and the Strategic Steering Committee.