Map of Lac Gagnon with depth contours

Lac Gagnon

46.1291° N, 75.1178° W

Depth contours from the 1977 government survey. Not for navigation.

Download the depth map (SVG)

Lac Gagnon is 71 m deep at its deepest point, deeper than 98% of the 1,506 surveyed lakes in Quebec. It covers 18.8 km² and lies 7.9 km northwest of Lac-Doré.

Maximum depth
71 msurveyed 1977
deeper than 98% of the 1,506 surveyed lakes in Quebec
Area
18.8 km²
larger than 97% of the 29,407 lakes in Quebec
Shoreline
53.3 km
longer than 96% of the 29,407 lakes in Quebec
Water clarity
6.5 mSecchi depth, 2025
clearer than 89% of the 805 monitored lakes in Quebec
Elevation
210 m

Today on the water

3.7 °C

Wind NE 3 km/h

Observed at Mont-Tremblant, as of 2:00 a.m. EDT

choppy Estimated waves, next 12 hours: up to 0.3 m.

Hourly forecast, next 24 hours
Time3 a.m.6 a.m.9 a.m.12 p.m.3 p.m.6 p.m.9 p.m.12 a.m.
Wind km/hW 10W 10W 10W 20W 20W 10W 10NW 10
Waves (est.) m0.10.10.10.3
Temp. °C76799741
Precip. %6040404040000

Tonight: Partly cloudy with 60 percent chance of showers. Wind west 20 km/h becoming light this evening. Low 6.

Weather: Mont-Tremblant (local forecast), as of 2:02 a.m. EDT

Sun and moon

Civil dawn
6:39 a.m.
Sunrise
7:09 a.m.
Sunset
6:25 p.m.
Civil dusk
6:55 p.m.
Moonrise
6:00 a.m.
Moonset
5:43 p.m.
Moon
Waning crescent, 1% lit

Data Source: Environment and Climate Change Canada. Local times.

How waves are estimated

Significant wave height from the forecast hourly wind and the open-water distance (fetch) upwind, using the SMB method (US Army Corps of Engineers Shore Protection Manual, 1984), rounded up to the next 0.1 m. It is not a measurement: gusts, leftover swell and shoals can make water rougher. Under 0.2 m: calm; 0.2–0.5 m: choppy; over 0.5 m: rough.

Depth

9% of Lac Gagnon is shallower than 3 m, and 41% is deeper than 30 m.

How to read it: the lake’s area is sorted from the shore to the deepest point. Where the curve is flat, large areas share one depth (flats and weed beds); where it drops, depth changes quickly (drop-offs).

The government depth survey from 1977 records a maximum depth of 71 m, drawn from 51 depth contours.

Not for navigation. Depths are from government surveys and may be outdated.

Water

Trophic status from the latest monitoring: oligotrophic.

Clarity was measured with a Secchi disk in 18 years between 2008 and 2025; the latest annual mean is 6.5 m.

Water clarity (Secchi depth, m)
Total phosphorus (µg/L)

Photos

Lac Gagnon vu du quai public 01
Photo: Fralambert, CC BY-SA 4.0, via Wikimedia Commons
Lac Gagnon vu du quai public 02
Photo: Fralambert, CC BY-SA 4.0, via Wikimedia Commons
Lac gagnon
Photo: Mr Pete man67, CC BY-SA 4.0, via Wikimedia Commons