Satellite Depth Map
Click the map to enlarge. The deepest basin — over 70 m — sits in the wide western half of the lake. The public boat launch is marked.
Depth shown in metres and feet (see on-map legend). Bathymetry: Géobase des bathymétries de lac du Québec (MELCCFP), via Données Québec. Satellite: Esri World Imagery.
About Lac Gagnon
Lac Gagnon stretches north from the village of Duhamel, deep in the Outaouais lake country on the edge of the Réserve faunique de Papineau-Labelle. It's one of the southernmost true lake-trout lakes in Québec, and one of the closest to Ottawa — roughly a 1h45 drive up the Lièvre and Petite-Nation valleys.
The lake is long, clear and cold, with a wide southern basin that drops past 71 m (233 ft) — cold-water habitat that holds touladi (lake trout, locally "truite grise"). It's a heavily fished water, so the lakers make you work: patient trolling with downriggers or heavy gear in 40–50 ft is the local playbook, especially around the Ernest River mouth and the Petite-Nation inflow.
Lac Gagnon also holds introduced ouananiche (landlocked salmon, stocked here about twenty years ago), along with walleye, northern pike and brook trout. There's lakeside camping and cottages around Duhamel, and a public boat launch — but note that access now requires a permit and a mandatory boat-wash, with a gated code system (see below).
- RegionOutaouais (Zone 10)
- Nearest villageDuhamel, QC
- From Ottawa~1h45 drive
- Length~12 km
- Max depth71 m (233 ft)
- Public launchCh. de la Grande-Baie (46.133, −75.126)
- Launch accessPermit + boat-wash; boats ≤ 30 ft
- CampingLakeside & cottages
- Fish speciesLake trout, ouananiche, walleye, pike, brook trout
Photos
Lac Gagnon from the public wharf — clear water and the forested Petite-Nation hills.
Photos: Fralambert, CC BY-SA 4.0, via Wikimedia Commons.
Fishing Regulations
Québec Zone 10 (Outaouais) · Source: Québec sport-fishing regulations. Limits and seasons change — always confirm the current Zone 10 rules before you fish.
⚠️ Lake trout (touladi) rules are tightened here. To protect a declining population, Lac Gagnon's daily limit is 1 fish (down from 2), the season runs April 23 – September 15, and kept fish must be 55 cm (22 in) or longer — a stricter minimum than the 45 cm general Zone 10 limit. Lake trout is angling-only.
| Species | Season (Zone 10) | Daily Limit | Notes |
|---|---|---|---|
| Lake Trout (Touladi) | Apr 23 – Sep 15 | 1 | Minimum length 55 cm (22 in) — stricter than the 45 cm general zone limit. Angling only. |
| Ouananiche (landlocked salmon) | Apr 23 – Sep 15 | 3 | Angling only. Introduced ~20 years ago; part of an ongoing touladi/ouananiche study. |
| Walleye & Sauger (doré) | May 15 – Dec 19 | 6 | Keep only walleye 37–53 cm; no size limit on sauger. Angling only. |
| Northern Pike (grand brochet) | May 15 – Dec 19 | 6 | |
| Smallmouth Bass (achigan) | Jun 15 – Dec 19 | 6 | Combined limit for bass species. |
| Brook Trout / Char (omble de fontaine) | Apr 23 – Sep 15 | 10 | At most 2 arctic char within the limit. |
| Lake Whitefish (corégone) | Apr 1 – Dec 19 | 5 | |
| Yellow Perch (perchaude) | Apr 1 – Dec 19 | 50 |
Limits are daily catch & possession for the 2026–27 season (Apr 1, 2026 – Mar 31, 2027), reflecting Lac Gagnon's exceptions within Zone 10. A general Québec fishing licence is required; "angling only" means line-and-hook fishing. Seasons and limits change year to year — confirm them in the official summary before keeping fish.
Touladi: Status & Conservation
Why the lake-trout rules are stricter here than on most Outaouais waters.
Lac Gagnon's touladi are a wild, naturally reproducing population — not a put-and-take stocked fishery. That makes them slow-growing and vulnerable to heavy harvest, and the lake sees a lot of fishing pressure for its size.
A 2017 summary study flagged worrying numbers, and the lake was singled out as the Outaouais water where lake trout had declined the most in recent years. A study led by the regional wildlife branch is examining whether the introduced ouananiche and the native touladi are competing for the same food in the Petite-Nation watershed. The tighter season and 1-fish limit are the management response.
The practical takeaway for anglers: consider catch-and-release on lake trout, handle deep-caught fish carefully, and follow the size limit. The Association des propriétaires du lac Gagnon (APLG) tracks the lake's fishery and regulation changes.
Lac Gagnon on Video
See the lake and the area before you make the drive.
Trip Tips
🎣 Find the lakers
Troll the deep southern basin and the drop-offs near the Ernest River and Petite-Nation inflow. Locals report fish in 40–50 ft — bring downriggers and electronics.
🐟 Mind the touladi limit
Only 1 lake trout per day, with a minimum-length limit and an Apr 23 – Sep 15 season. Consider releasing the bigger fish — it's a stressed population.
🚤 Launch: permit + wash
The public launch is on Chemin de la Grande-Baie. Access needs a permit and a mandatory boat-wash (~$30–40), and since July 2025 a gated code system controls exit. Boats 30 ft or less. Camping Poliquin has a second launch — ask in the village.
📋 Check Zone 10 regs
Lac Gagnon is in Québec fishing Zone 10. Verify seasons, limits and size rules before you go.
Getting There
From Ottawa–Gatineau, head up Highway 309 through the Lièvre Valley to Duhamel (about 1h45), then follow Chemin du Tour-du-Lac to Chemin de la Grande-Baie, which leads to the public boat launch (≈ 46.133, −75.126) on the lake's west-central shore. Stop at the boat-wash station in the village first — a wash and access permit are required, and parking at the launch is limited.