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Map of Lac Thomas with depth contours

Lac Thomas

46.3835° N, 73.2408° W

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

Download the depth map (SVG)

Lac Thomas, Quebec. 46.3835° N, 73.2408° W

Maximum depth 20.3 m (1977 survey). Scale bar on the map.

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 Depths are from government surveys and may be outdated.

borealbound.ca/lakes/qc/lac-thomas-near-saint-gabriel/, 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 Thomas is 20.3 m deep at its deepest point, deeper than 63% of the 1,506 surveyed lakes in Quebec. It covers 0.5 km² and lies 3.1 km northwest of Californie.

Maximum depth
20.3 msurveyed 1977
deeper than 63% of the 1,506 surveyed lakes in Quebec
Area
0.5 km²
larger than 62% of the 29,407 lakes in Quebec
Shoreline
6.5 km
longer than 69% of the 29,407 lakes in Quebec
Water clarity
4.8 mSecchi depth, 2025
clearer than 68% of the 805 monitored lakes in Quebec
Elevation
188 m

Today on the water

YELLOW ADVISORY - FROST · issued 4:39 a.m. EDT
Temperatures will drop to near the freezing mark overnight tonight.

Take preventative measures to protect cold-sensitive plants, trees, and crops.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to QCstorm@ec.gc.ca or post reports on social media using #QCStorm.

Official alert on weather.gc.ca · expires 8:39 p.m. EDT

7.3 °C

Light RainWind W 8 km/h

Observed at Lanaudière, as of 5:00 a.m. EDT

calm Estimated waves, next 12 hours: up to 0.1 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 10W 20W 20W 20W 20W 10W 10NW 10
Gusts km/h404040
Waves (est.) m0.10.10.10.10.1
Temp. °C610121311853
Precip. %404040400000

Today: A mix of sun and cloud with 40 percent chance of showers. Risk of a thunderstorm this afternoon. Wind becoming west 20 km/h gusting to 40 this morning. High 13. UV index 3 or moderate.

Weather: Lanaudière (local forecast), as of 5:02 a.m. EDT

Sun and moon

Civil dawn
6:32 a.m.
Sunrise
7:02 a.m.
Sunset
6:17 p.m.
Civil dusk
6:47 p.m.
Moonrise
5:52 a.m.
Moonset
5:35 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

32% of Lac Thomas is shallower than 3 m, and 19% 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 1977 records a maximum depth of 20.3 m, drawn from 39 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 16 years between 2010 and 2025; the latest annual mean is 4.8 m.

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