October 13, 2017

Coquihalla Calling: Dynamite to the rescue for a stranded stock of steelhead

If you live in southern B.C., chances are the name "Coquihalla" is synonymous with the sometimes-treacherous highway connecting the south coast to the Okanagan. You may also know that this highway was named for the river it frequently crosses – one of only two rivers in the Lower Fraser watershed that supports a summer run of wild steelhead.

The Coquihalla River is indeed special; the fisheries on this river are almost entirely dedicated to steelhead, although a few coho and bull trout may be caught incidentally. While both summer- and winter-run steelhead occur here, it is mostly the summer run that attracts anglers. This small river provides some excellent fly-only fishing in a majestic setting punctuated by crystal-clear, turquoise pools and towering mountains.

Fisheries management here has always been challenged by two factors: the presence of both summer and winter steelhead runs, and Othello Falls, a natural barrier that slows the migration of fish. It’s this cascade that separates the summer- and winter-run fish stocks. Summer-run steelhead tend to hold below this barrier until the water flows are just right in early summer – not too high, but not too low. This window allows only the summer-run fish, still with some difficulty, to pass. When these ideal water flows come in, the fish pound their way up through the Coquihalla Canyon, often attempting the feat dozens of times without making any headway at all. Driven by the innate need to return to their natal spawning grounds, they demonstrate incredible stamina, a trait shared by many summer steelhead stocks intent on reaching these waters in the upper sections of coastal streams.

In the spring of 2014, the balance shifted - creating an almost impossible situation - when a railway support abutment (a remnant from the now-defunct Kettle Valley Railway) slumped into the river, pushing a particularly large, problematic boulder into the channel. Othello Falls was altered such that, even when early-summer water flows increased, most summer steelhead could no longer surmount the falls. Since that disaster, adult steelhead were cut off from the upper 20 kilometres of the river’s rearing and spawning habitats. This not only resulted in poor angler success for the fly-only summer steelhead fishery, but also had the potential to lead to the ultimate demise of this special stock of fish.

Once provincial fisheries biologists had confirmed that summer steelhead were unable to access upper sections of the river, a major collaboration involving several partners was initiated in 2016 to formulate a plan of attack. The solution would require the removal of some of the debris from the 2014 slide, as well as replicating the original falls so the partial barrier that separated the summer and winter runs of steelhead (as well as other species that could not originally ascend this barrier) could be re-established. This would be no small feat, and one requiring significant technical expertise.

While engineers waited for the perfect conditions to start rehabilitating the water flows over Othello Falls, biologists worked each year since 2014 to get as many summer steelhead moved upstream as possible. In this way, at least some spawning could still occur.

On September 28, 2017, the stars aligned. After much preparation, including crews rappelling into the canyon to install explosives, a major chunk of the problem boulder was blasted away. Clearly, the result is improved water flows through the critical section, but the boulder modification will still need the assistance of Mother Nature during the next few freshets (high flow events that we anticipate will take place over the fall and winter months) to continually move the rock debris and allow fish passage. Only time will tell if summer steelhead can get through this section on their spawning migration next year.

The Society would like to acknowledge other partners in this project, including the Habitat Conservation Trust Foundation, Steelhead Society of B.C., Kingfishers Rod and Gun Club, and B.C. Conservation Foundation. Staff from BC Parks and from Forests, Lands and Natural Resource Operations, as well as funds from the Steelhead Caucus, have also supported this initiative.

To learn more about this Freshwater Fisheries Society of BC - funded project, contact Mike Willcox, BC Ministry of Forests, Lands and Natural Resource Operations at Michael.Willcox@gov.bc.ca  

This series has been established as a way to inform freshwater anglers in B.C. about projects that their angling licence dollars support. In 2015, the Freshwater Fisheries Society of BC began receiving 100% (up from 70%) of all freshwater angling licence fees. With this additional funding, the Society committed to broadening the scope of its activities to include joint initiatives with the Provincial Government to support projects that benefit freshwater recreational fishing around B.C.

Author: Sue Pollard, Freshwater Fisheries Society of BC
Photo Credit: Mike Willcox, BC Ministry of Forests, Lands and Natural Resource Operations
Video Credits: Northwest Hydraulic Consultants, Lise Galand and Dusty Waite