No standalone Fosthall Creek entry appears in the Region 4 synopsis. Apply the region-wide defaults: no fishing in any stream April 1 to June 14, trout and char catch-and-release in streams November 1 to March 31, single barbless hook year-round, and a bull trout daily quota of one, any size. Confirm the current synopsis at gov.bc.ca before you fish.

NRCan/GeoGratis places the creek's mouth at 50.360833, -117.9425 (key JAGQV), on Upper Arrow Lake at Fosthall Bay, roughly 14-16 km north of Nakusp along the same shore. A second, separate water, South Fosthall Creek (key JBKVZ), enters the lake a little further south near 50.369, -118.034 and carries its own, stronger fish-record history; don't confuse the two when reading local maps or older reports. Fosthall Creek itself runs stream order 5 (mid-range toward river scale on the 1-to-6+ network used across this vault) for roughly 32 km before reaching the lake.

Provincial fish-inventory data directly confirms rainbow trout and sculpin in Fosthall Creek. Bull trout and westslope cutthroat are reachable habitat under barrier-aware connectivity modelling, and dolly varden also shows up in the broader habitat read for this drainage, though none of the three has a direct record on file yet (no dedicated species page exists for dolly varden either).

Above the bay, fish it like a small Monashee-side tributary: short drifts with a buoyant dry over a light dropper through the pocket water and pool heads, the same small-stream dry-fly approach that works across the region's cutthroat creeks. At the mouth itself, rainbow trout and any staging char will sit off the creek's plume where cooler, oxygenated water meets the lake, worth a few casts from a boat before heading up the trail.

No hatch report specific to Fosthall Creek has turned up. Until one does, fish the general moving-water calendar mined from the wider East Kootenay corridor as a starting point rather than a confirmed local hatch: golden stoneflies into early summer, summer mayflies, caddis from mid-June, and terrestrials as the water drops in August. Start with a Stimulator, small Chubby Chernobyl or Royal Wulff, switch to an Adams or Elk Hair Caddis as fish get selective, and carry Hare's Ear and Pheasant Tail nymphs for the pocket water. The confirmed sculpin record backs up a small Woolly Bugger or Muddler Minnow for any bull trout working the creek mouth.

No dedicated habitat or water-quality survey specific to Fosthall Creek has turned up. Treat the drainage with the same care as any Monashee-side spawning tributary: keep to established trails near the bay, and avoid disturbing spawning gravel if you fish the creek mouth in season.

Fosthall Bay itself is boat-in only, roughly 14-16 km up Upper Arrow Lake's west shore from Nakusp; there's no drive-in road to the bay. A recreation site with informal camping sits close to the creek, and a short trail climbs from the bay to Fosthall Falls. Whether a Forest Service Road reaches the bay from inland, or only serves the upper drainage, isn't confirmed. No guide coverage specific to Fosthall Creek was found.