Confirm the current BC freshwater fishing regulations (Region 4 – Kootenay) before you fish; this water is part of the Pend-d'Oreille River system.

It flows into pend d oreille river within the Lower Arrow Lake watershed (Lower Arrow Lake → Columbia River). It runs stream order 4 (mid-range in the network; the scale runs from 1 for a headwater trickle to 6+ for a river) and roughly 6 km. bull trout, rainbow trout, recorded here in provincial fish-inventory data (2 records). The fish-passage model expects Westslope (Yellowstone) Cutthroat Trout here too, since the reach is reachable with no barrier between, though there is no direct record yet. Named tributaries: wally creek, key creek.

As a small stream, a tributary of Pend-d'Oreille River, Boulder Mill Creek fishes the way creeks of its size do: short drifts with a buoyant attractor dry over a light dropper, working the pocket water and the heads of pools. Match the fly box to the season and confirm against a current local report.

Access for Boulder Mill Creek, meaning the roads in, put-ins and any walk-in or seasonal limits, is worth confirming locally before you commit a day. The drainage map shows how the water sits in its valley.