O'Brien Creek has no individual listing in the Region 4 table. Treat it as an upper Duncan / Duncan Lake tributary: the Duncan Lake tributary group (4-27) carries a standing bull trout release rule alongside the Upper Duncan River and its tributaries, plus the general stream defaults (closed Apr 1 to Jun 14, trout and char release Nov 1 to Mar 31, single barbless hooks). Do not apply Duncan River mainstem exemptions, quotas or bait wording here unless the official table or regional office confirms it. Confirm the current synopsis before you fish.

NRCan's Geographical Names database lists O'Brien Creek as an official Kootenay Land District name (key JBFWL), at 50.741111, -117.160833; a separate Coast Land District O'Brien Creek record refers to a different water entirely. It runs stream order 3 (low on a scale that runs from 1 for a headwater trickle up to 6 or more for a full river), about 4 km long, one of a cluster of small, similarly unrecorded upper-Duncan tributaries alongside Jinx and Irene creeks. Channel-geometry data puts the median width at about 1.8 m (narrow), median gradient at about 28.77% (very steep), and peak mean-annual discharge at about 0.226 m³/s (very low flow), the profile of a small, technical headwater creek rather than a fishable valley-bottom stream.

No named-line fish records exist for O'Brien Creek in the provincial inventory data. The wider upper-Duncan watershed context lists westslope cutthroat, bull trout, rainbow trout, kokanee, mountain whitefish and burbot as species present in the broader system, so any of those could plausibly turn up here, but that is a watershed-level inference, not a confirmed local population. No public fishery report, hatch report or creek-specific guide coverage backs it up. Reel Adventures Fishing Charters covers Duncan Lake at the lake/charter level, not this creek.

No public access point, trailhead, parking area or road condition has been confirmed for O'Brien Creek. Do not assume roadside or trail access exists until a local source confirms it.