Troubled waters: Intermittent pollution in Bowker Creek a mystery

Not long ago, Bowker Creek was a trash-filled urban creek riddled with pollutants, a mere shadow of its former days as a salmon-spawning hotspot. But thanks to the dedication of local scientists and volunteers, the creek has returned to its pristine state—salmon might even be returning to the waters after a century without spawning. A decade of hard work made the creek a conservation success story.

But the battle to maintain Bowker Creek is ongoing, with urban pollutants continually popping up throughout the creek, which starts near UVic and runs through Saanich, Victoria, and Oak Bay before emptying into the ocean near Glenlyon Norfolk Junior School.

A photo shared last week to the Oak Bay Local Facebook group sparked concern about a mysterious runoff flowing into the creek. The photo was taken near Oak Bay Secondary School and showed murky white water flowing through the creek.

The source of the contamination is not clear—some have speculated paint, others say it could be construction runoff. But because Bowker Creek runs through three municipalities, it's tricky to nail down where the substance originated.

Friends of Bowker Creek (FOBC), an organization dedicated to conserving the creek and reintroducing salmon spawning to the waters, was made aware of the issue last Tue., as were the public works departments in both Oak Bay and Victoria. FOBC has since heard similar reports of white water seen the day before, and noticed a lingering, but faded, grey/white colour Wed. morning.

Eldan Goldenberg, water quality tester for FOBC, says a construction site seems likely to be the source, “but we can't be certain of that.”

FOBC has determined the water becomes dirty in the creek at the culvert under the intersection at Fort, Cadboro Bay, and Foul Bay. However, multiple storm drains coming from all three municipalities are connected to this culvert. Goldenberg says he agrees with Saanich staff that it’s likely not coming from Saanich. Oak Bay says last week’s spill did not come from within its borders either.

Victoria spokesperson Colleen Mycroft said the city was made aware of the spill last Tue. afternoon. There was another report of grey water in the creek the next day. Both Oak Bay and Victoria dispatched crews. On each occasion, Victoria staff said the water was running clear soon after receiving the report.

Victoria is working with Oak Bay to monitor the water to determine the source of the spills. Mycroft says the city takes any report of pollution in its waterways very seriously and will respond immediately to any concern. However, tracking the source of intermittent discharge in the creek can be tough, she says, since the water can move through the drain system quickly.

The problem with foreign substances in the creek

Without knowing what the contaminant is, it’s difficult to say what the effects could be. If silt from a construction site ends up in the creek, it can be abrasive to organisms in the water, says Goldenberg. It can also affect the dynamic of predator and prey, and smother wildlife living at the bottom of the creek.

“The first year that we put chum eggs in the creek, we had significant mortality which we think was probably caused by silt suffocating the eggs as they developed,” said Goldenberg.

If a chemical pollutant like paint ends up in the water, it can have a range of effects. If the pollutant is acutely toxic, it can kill fish or invertebrates quickly. Some take longer to show their side effects, accumulating over time.

“The problem gets worse as you look up the food chain,” Goldenberg said. “Invertebrates and small fish may never reach a high enough concentration to do them harm, but long-lived top predators—like marine mammals and humans—can gradually accumulate much higher doses over the years.”

More than one issue happening in the creek

Goldenberg said FOBC is tracking multiple issues in the creek. Near Browning Park, volunteers have noticed intermittent severe turbidity (murky water) throughout the year and are “reasonably sure” it’s caused by silt runoff from construction sites.

“Saanich public works has worked with multiple construction sites to improve their water handling, though this seems to be something that we still need to keep monitoring,” Goldenberg said.

Lower than normal oxygen levels at the moment have been a concern as well. It’s typical to see a drop in oxygen levels after the summer, when seasonal algae blooms die off, but this year, the oxygen hasn’t improved as quickly as it should.

“In previous years, oxygen levels had bounced back by December, but this year, we're still seeing worryingly low dissolved oxygen and don't yet know why,” Goldenberg said.

FOBC is working with the BC Conservation Fund and VIU to measure the level of 6PPD-Quinone—a chemical found in car tires that is toxic to coho salmon in small concentrations—in the creek. Last winter, there were readings high enough to kill coho during notable rainstorms. This year’s data are still being processed.

There have been high bacteria counts as well, with some reports of a sewage-like smell at Monteith in Oak Bay. Goldenberg said it’s not clear what’s driving either of these issues.

If you see something, say something

Goldenberg stressed it’s important to contact the CRD and municipal public works if you see something concerning, such as colour changes or trash in the water. Volunteer-led organizations like Friends of Bowker Creek have limited resources to track and test the water.

The CRD offers a comprehensive list of contacts—including different municipal contacts—for different issues in Bowker Creek and other waterways.