Efforts to rebuild the Okanagan kokanee salmon populations have been dealt a crushing blow by the spring drawdown of the level of Okanagan Lake, according to the BC Wildlife Federation (BCWF).
The BCWF is accusing the province of seriously undermining a 28-year effort to recover the salmon run, with 316,000 shore-spawning fish returning in 2020, the highest rate since the 1970s and 214 per cent of the 10-year average.
A posting to the BCWF website indicated in early March, government biologists and First Nations partners became concerned the annual drawdown was prematurely exposing shoreline spawning areas, stranding unhatched kokanee eggs and immature fry, according to documents released under the Freedom of Information and Protection of Privacy Act.
The OKN warned the government that the predicted final emergence day for kokanee fry was “too early.”
But a government consultant advised that “the correct 100 per cent emergence prediction for kokanee this year is March 12, 2021.”
Sampling in the field showed kokanee fry were not as mature as anticipated, they could not swim freely and “therefore significant numbers would be stranded by further lake level drops.”
An excavation of shoreline gravel, led by a government biologist, found mainly dead eggs in the 25-centimetre vertical drawdown zone.
“The majority of kokanee observed were still in eggs stage and deceased,” the report concluded.
Patrick Whittingham, Okanagan Region president for the BCWF, said the millions of dollars and countless volunteer hours have been spent to rebuild the kokanee spawning run.
“By drying these eggs up we may have just set ourselves back decades,” Whittingham said in the BCWF post.
Jesse Zeman, director of the fish and wildlife restoration program for the BCWF, echoed a sentiment that has become increasingly widespread across the Okanagan Valley – the provincial government water modelling strategies for Okanagan Lake have not kept up with the effects of climate change on runoff and the lake itself.
Peachland council initiated the questioning of current lake level management policies, and it has since been picked up by the Okanagan Basin Water Board, which is now talking with the provincial authorities about a study to review that process, which dates back to the 1970s.
For Okanagan municipalities, the concern is infrastructure and property damage caused by repeated flooding in recent years.
Zeman noted holding the water level high in the spring increases the risk of flooding because the water release infrastructure is not adequate to manage water levels on a day-to-day basis.
And a large release of water downstream of Penticton can also negatively impact sockeye fry which emerge in the Okanagan River.
Zemen added the Penticton dam can only lower the lake’s level by about 1.75 centimetres a day while climate change-induced spring runoff can raise the lake level up to seven or eight centimetres.
He said the interim solution is to draw down Okanagan Lake before Octob er, so the kokanee spawners lay their eggs further down the shoreline.
“In the short-term, B.C. needs a watershed security fund and strategy to deal with the earlier and more intense spring runoff followed by dry summers we’re currently experiencing,” Zemen said.
“In the long-term Okanagan Valley homes and buildings are going to have to be built or moved further from the lake and stream edges so that these unprecedented runoff and drought cycles do not continue to flood people’s property.
“That sounds like a radical solution, I know, but the climate is changing and we have to adapt to a new reality.”