Skip to content

Out of the streambed gravel comes harbinger of waning pollution in Oak Bay creek

Volunteers find more than 30 caddisfly larvae in Bowker Creek

Filtering through the gravelly bottom of Bowker Creek in Oak Bay, volunteers uncovered a small set of unlikely heroes.

Caddisfly larvae found in the streambed serve as a key indicator of water quality, as the larvae can’t live in heavily polluted streams.

Brandon Williamson, who graduated two years ago with a biology degree from the University of Victoria, was among the volunteers who fished out the critters, and understands what they signify.

“It is a good sign for the creek. It’s not to say water quality conditions are perfect there. There are definitely some ongoing issues there we’re investigating.”

Williamson started volunteering with the Bowker Creek Chum Salmon Recovery Project after losing his job in the early days of the COVID-19 pandemic. The Victoria resident saw an opportunity to give back to the community and immerse himself in something of interest, working to restore the waterway that flows through Saanich, Oak Bay and Victoria.

READ ALSO: Friends of Bowker Creek to plant 30,000 salmon eggs in Oak Bay section

“I’ve just enjoyed the volunteer community and like seeing positive change and bringing nature into the community,” Williamson said.

Invertebrate surveys are a common part of stream biomonitoring because you can glean a lot of information about year-round water quality and stream conditions, Williamson explained. Essentially there are three major groups of invertebrates that are pollution intolerant caddisfly, stonefly and mayfly.

Williamson, now an invertebrate sorting technician with Biologica Environmental Services, was among the volunteers who filtered 33 larvae from a segment of the creek near the Monteith allotment gardens. It’s where the habitat revitalization team hopes to plant salmon eggs next year.

They found one caddisfly larva last year.

The samples were analyzed at the scene, preserved, then sent off to the lab. This year, his employer donated some time to have the invertebrate samples from the stream professionally assessed. Now the team awaits results from Biologica.

READ ALSO: Volunteers move masses of gravel, rock into Oak Bay creek

While they may not look cute to the average person, Williamson swears that under the microscope the caddisfly larvae actually have very cute faces. Plus, they’re a harbinger of good things.

“Things can vary from year to year but it looks like things are moving in a positive direction.”

Christine van Reeuwyk

About the Author: Christine van Reeuwyk

I'm dedicated to serving the community of Oak Bay as a senior journalist with the Greater Victoria news team.
Read more