Confirm the current BC freshwater fishing regulations (Region 4, Kootenay), including any bait, motor or ice-fishing limits specific to this lake, before you fish.

Diamond Lake sits in the same small-lakes country as Premier Lake, part of the St. Mary River drainage in the East Kootenay. It carries rainbow trout only, no other stocked or recorded species, and it fishes as a quiet, low-pressure water next to its much larger neighbour.

For an angler judging whether the fishing is worth the drive, the stocking record is the fishing report. Diamond Lake has been on a fry-stocking program since 1990: 17 recorded releases totalling 11,500 rainbow trout, most of them 500-fish drops on a roughly two-year cycle. The first few releases (1990 to 1998) used Premier, Beaver, Tunkwa, Genier and Badger stock as yearlings or fall fry; every release since 2000 has been Pennask-strain fry, the most recent on November 1, 2024.

That steady, small biennial top-up makes it a put-grow fishery rather than a put-and-take one: the 500 Pennask fry dropped every second fall are effectively this lake's whole recruitment, growing on natural forage through the seasons between plants rather than being caught the same year they go in.

No water-specific report is on file for Diamond Lake, so fish it on the standard small-lake stillwater program until a local account says otherwise: a chironomid under an indicator over the shoals in spring, then leech and attractor patterns worked along any drop-off as the water warms through summer. Because recruitment comes from small fry plants rather than catchable-sized fish, expect a lake of grown-on rainbow rather than fresh stockers, sized by how many seasons have passed since their release year.

No boat launch, trailhead or parking location is on file for Diamond Lake itself. Confirm the approach, parking and any motor or float restrictions locally before you commit a day to it; the map shows where it sits relative to Premier Lake and the wider St. Mary River drainage.