The Koksilah Canyon is the closest commonly paddled river to Victoria, and is a good introductory creek run which needs rain for runnable levels. The Upper Koksilah (III) is immediately upstream. Look for these runs and others in an upcoming guidebook by the Vancouver Island Whitewater Paddling Society.
This section is runnable at a variety of flows, and will spike up and down very quickly. Look for wood floating down the river as a clue that it may still be spiking upwards. A bare minimum flow is 10cms, which will be scrapey but all the rapids still go. A better entry level low-medium flow is 20-30cms. Some of the best padded medium flows are in the 50cms range, when the river comes alive with many surf waves and dynamic eddies. As flows approach 100cms, the river becomes boily class IV-V.
To get there, drive about an hour north of Victoria on Highway 1, and turn left on Koksilah Rd. for just over 2km to a bridge over the river next to Jack Fleetwood Memorial Park. The parking for the put in trail is 10km up Riverside Drive on river left, at the north access for the Kinsol Trestle. From here, hike ~500m south along the Cowichan Valley Trail, and drop down to river level just before the trestle on the upstream side.
The run is mostly read and run class III-IV through open rapids with some bedrock shelves and boulders, a few small canyons, and one common portage. Following some read and run warmup, the first notable rapid is a triple drop, scouted on the right. After a boulder fence and some boogie water is the crux "fish ladder" drop (IV+), a ~3m ledge on either side of a bedrock island. The preferred left channel goes better at some levels than others, while the not recommended right channel has issues with rebar and a retentive hole. The eddy most commonly used for scouting and portage is on the left, immediately at the lip of the drop. There are other portage options, and if this run is near your skill limit you'll be better off having a local show you down. After the crux ledge, there is some more read and run, one more big rapid, and a scenic paddle out through a sandstone canyon.