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Map of Lac Sébastien with depth contours

Lac Sébastien

48.6581° N, 71.1675° W

Depth contours from the 1981 government survey. Not for navigation.

Download the depth map (SVG)

Lac Sébastien, Quebec. 48.6581° N, 71.1675° W

Maximum depth 24.3 m (1981 survey). Scale bar on the map.

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 Depths are from government surveys and may be outdated.

borealbound.ca/lakes/qc/lac-sebastien/, compiled October 9, 2026

  • Canadian Geographical Names Database, Natural Resources Canada. Contains information licensed under the Open Government Licence – Canada.
  • HydroLAKES v1.0, Messager et al. 2016 / WWF HydroSHEDS. Licensed under CC BY 4.0.
  • Census boundaries and population, 2021, Statistics Canada. Adapted from Statistics Canada. This does not constitute an endorsement by Statistics Canada.
  • Géobase des bathymétries de lac du Québec (GBLQ), Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs. Licensed under CC BY 4.0. Source: Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (MELCCFP), Données Québec.
  • États trophiques des lacs (RSVL), Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs. Licensed under CC BY 4.0. Source: Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (MELCCFP), Données Québec.
  • City page weather forecasts and alerts, Environment and Climate Change Canada. Contains data from Environment and Climate Change Canada (ECCC Data Servers End-use Licence).

Lac Sébastien is 24.3 m deep at its deepest point, deeper than 73% of the 1,506 surveyed lakes in Quebec. It covers 2.9 km² and lies beside Chute-aux-Galets.

Maximum depth
24.3 msurveyed 1981
deeper than 73% of the 1,506 surveyed lakes in Quebec
Area
2.9 km²
larger than 87% of the 29,407 lakes in Quebec
Shoreline
30.1 km
longer than 92% of the 29,407 lakes in Quebec
Water clarity
2.9 mSecchi depth, 2024
less clear than 70% of the 805 monitored lakes in Quebec
Elevation
169 m

Today on the water

6.4 °C

Wind WNW 12 km/h

Observed at Saguenay, as of 4:00 a.m. EDT

choppy Estimated waves, next 12 hours: up to 0.2 m. Around 6 a.m., wind from the west: the west shore is sheltered, waves build toward the east shore.

Time6 a.m.9 a.m.12 p.m.3 p.m.6 p.m.9 p.m.12 a.m.3 a.m.
Wind km/hW 20W 20W 20W 20W 20W 20W 20W 20
Gusts km/h4040404040404040
Waves (est.) m0.20.20.20.20.2
Temp. °C55666443
Precip. %4040404040404040

Today: Mainly cloudy with 40 percent chance of showers. Wind west 20 km/h gusting to 40. High 7. UV index 3 or moderate.

Weather: Saguenay (local forecast), as of 5:05 a.m. EDT

Sun and moon

Civil dawn
6:24 a.m.
Sunrise
6:55 a.m.
Sunset
6:07 p.m.
Civil dusk
6:38 p.m.
Moonrise
5:45 a.m.
Moonset
5:25 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

7% of Lac Sébastien is deeper than 10 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 1981 records a maximum depth of 24.3 m, drawn from 62 depth contours.

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

Water

Trophic status from the latest monitoring: meso-eutrophic (transition).

Clarity was measured with a Secchi disk in 17 years between 2008 and 2024; the latest annual mean is 2.9 m.

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