No Marion Creek-specific exception is listed in the checked Region 4 extraction. Default Region 4 stream rules apply: closed Apr 1 to Jun 14, trout and char release only Nov 1 to Mar 31, and single barbless hook year-round on all Region 4 streams. Confirm the current synopsis before fishing, and avoid the isolated cutthroat reach above the Highway 95 barrier regardless of season.

Marion Creek's mouth sits at 50.22591, -115.90405. It runs stream order 4 (mid-range in the network, on a scale that runs from 1 for a headwater trickle up to 6 or more for a full river), draining a 36 km² watershed with headwaters around Mount Marion before entering Columbia Lake through a culvert under the railway on the lake's west shore. Channel-geometry data puts it at a narrow ~3.5 m median width, a gentle ~1.33% gradient and a very low ~0.187 m³/s peak mean-annual discharge, consistent with a small, wadeable tributary rather than driftable water.

Restoration crews have logged riparian and cattle fencing, a bridge replacement, and wetland and stream restoration planning along the creek. The mid and lower reaches also run heavily modified through open cattle fields and irrigation ponds, and summer monitoring has recorded temperatures above the preferred range for rearing trout in those reaches.

Local beat records hold only 3 direct fish observations on Marion Creek: two cutthroat trout and one northern pikeminnow. The real signal is upstream of the Highway 95 barrier, where the only documented population is a 99.3% pure-strain westslope cutthroat trout, protected by the isolating culvert itself. Below the highway, surveys have turned up sculpins, suckers, mountain whitefish fry at the Columbia Lake confluence, one captured juvenile mountain whitefish and one juvenile rainbow trout, a thin, mixed community typical of a small, warm-margin lake tributary.

If a legal, cool-water lower reach is confirmed, carry a conservative small-stream box: Adams, Royal Wulff, a small Stimulator, Elk Hair Caddis, Hare's Ear, Prince Nymph and Pheasant Tail, with a tiny olive or black Woolly Bugger for the sculpin- and fry-holding water near the lake. Food in that lower, lake-connected stretch runs to mayflies, caddisflies, small stoneflies, summer terrestrials, sculpins, suckers, whitefish fry and other micro baitfish and fry drifting in from Columbia Lake.

The creek crosses Highway 95 about 5 km north of Canal Flats, and that crossing is the best-documented landmark, since it marks the perched culvert barrier that protects the upper cutthroat population. No named trailhead, parking area or confirmed public access point has turned up for Marion Creek, and land tenure along the creek has not been verified. Kootenay Troutfitters is the nearest Columbia Valley guide outfit, but no source confirms dedicated Marion Creek guiding.