A local environmental advocate fears a recent spill of warm, sediment-rich water into the Colquitz River system could lead to the failure of future salmon runs.
Ian Bruce, executive director of the Peninsula Streams Society, expressed this fear after he and others witnessed the river turn “chocolate brown” on Thursday, May 2. Students from Royal Oak middle school were releasing Coho fry into the river at the Wilkinson Road and Lindsay Avenue when the level of the river suddenly rose four inches in height, said Bruce, whose organization hosted the students.
“The clear, slow moving water became chocolate brown with sediment, and began rushing by,” he said. Its temperature rose from 10.8 degree Celsius to 18.5 degree Celsius, while the level of dissolved oxygen dropped by more than half, he added.
After calling authorities, Bruce and others then followed the river to discover that the water had entered the Colquitz River through Viaduct Creek, an upstream tributary, that runs near the Horticultural Centre of the Pacific (HCP).
“At the site where the man-made lake behind [HCP] enters Viaduct Creek, we found evidence of beaver dam removal from the weir and overflow spillways with lots of sediment and the water from the lake rushing into the creek, then into the Colquitz River via Quick Bottom wetland.”
Bruce expects the incident will have immediate and long-term impacts. Immediate impacts of the spill include the potential death or definite impairment of Coho fry and [smolt] Cutthroat eggs and juveniles, and aquatic insects on which salmon juveniles rely for their food, said Bruce. “Longer term impacts could include failure of future runs,” he added.
The timing of the incident could not have been worse or more instructive.
“We had just asked the Grade 6-7 [students releasing the fry] about what a stream needs to be healthy,” he said. “[Clear], oxygenated water was their answer just before this bad water appeared.”
Thursday’s incident adds another line to a long list of incidents involving spills into the river, which the Peninsula Streams Society and others have sought to restore as a salmon-bearing river.
Bruce said Salmons already face so many threats that are not easily controlled, including climate change, not to have preventable incidents like this to happen.
The Saanich News has reached out to HCP and the ministry of environment for comment.