Westfall sits in the Duncan Lake tributary group of the Region 4 table, where Upper Duncan River and tributaries carry a bull trout release requirement. No Westfall-specific exception appears beyond that Duncan Lake tributary rule and the general Region 4 stream defaults: closed Apr 1 to Jun 14, trout and char release Nov 1 to Mar 31, and single barbless hooks required. Confirm the current synopsis before fishing.

NRCan lists Westfall River as an official Kootenay Land District name at 50.781111, -117.197778. It runs as a fifth-order stream (order 5, on a scale that runs from 1 for a headwater trickle up to 6 or more for a full river) for roughly 29 km east into the Upper Duncan River. BC Hydro's monitoring reports describe a steep lower bedrock canyon, a high-elevation upper watershed, and comparatively little glacial input next to other Upper Duncan tributaries, along with two notable side streams, marsh adams creek and silvertip creek.

Treat Westfall as conservation water first. Six direct bull trout catches sit on record, and the Okanagan Nation Alliance selected Westfall as the best repeated redd-survey site for the Duncan Reservoir Fish Habitat Use Monitoring Program, estimating that roughly 30 percent of the watershed's bull trout use it to spawn. BC Hydro's bull trout migration monitoring ties these Westfall-origin fish to repeated movement between the Duncan system and kootenay lake through Duncan Dam passage. If you fish it at all, keep to clear, low water outside the spawning window, stay off visible redds and staging fish, and bring any legal catch-and-release contact in quickly.

Westfall's food base follows its bull trout: small fish first, juvenile trout and char, kokanee and sculpin where the lower river connects to Duncan water. No water-specific hatch survey exists for Westfall itself, but its cold, high-elevation character points to the same stoneflies, mayflies, caddisflies and terrestrials that carry the rest of the Upper Duncan system. If conditions and timing make legal, ethical fishing possible, carry small to medium sculpin or kokanee-fry streamers alongside a woolly bugger, prince nymph, hares ear nymph, pheasant tail nymph, elk hair caddis, stimulator, adams and royal wulff. None of this is built around casting to spawning fish.

The Westfall Forest Service Road tracks much of the lower river, but upper-watershed access has been reduced since a partial deactivation aimed at cutting traffic and protecting caribou habitat. No public guide runs dedicated Westfall trips; treat any duncan river or duncan lake guide listing as regional context rather than Westfall-specific coverage. Confirm current road, tenure and closure status before heading in.