Grand lac Saint-François
45.8986° N, 71.1583° W
Depth contours from the 1972 government survey. Not for navigation.
Download the depth map (SVG)Grand lac Saint-François, Quebec. 45.8986° N, 71.1583° W
Maximum depth 39.8 m (1972 survey). Scale bar on the map.
Not for navigation. Depths are from government surveys and may be outdated.
borealbound.ca/lakes/qc/grand-lac-saint-francois/, 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).
- Photographs, Wikimedia Commons contributors. Each photo carries its own licence (CC0, public domain, CC BY or CC BY-SA), credited where shown.
Grand lac Saint-François is 39.8 m deep at its deepest point, deeper than 89% of the 1,506 surveyed lakes in Quebec. It covers 49 km² and lies 6.9 km east of Domaine-des-Pins.
- Maximum depth
- 39.8 msurveyed 1972
- deeper than 89% of the 1,506 surveyed lakes in Quebec
- Area
- 49 km²
- larger than 99% of the 29,407 lakes in Quebec
- Shoreline
- 117 km
- longer than 98% of the 29,407 lakes in Quebec
- Water clarity
- 2.6 mSecchi depth, 2025
- less clear than 76% of the 805 monitored lakes in Quebec
- Elevation
- 283 m
Today on the water
4.9 °C
Observed at Thetford Mines, as of 2:00 a.m. EDT
choppy Estimated waves, next 12 hours: up to 0.3 m.
| Time | 3 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/h | W 10 | W 10 | W 20 | W 20 | W 20 | W 20 | W 15 | W 10 |
| Gusts | 40 | 40 | 40 | |||||
| Waves (est.) m | 0.2 | 0.2 | 0.3 | 0.3 | ||||
| Temp. °C | 9 | 9 | 9 | 10 | 11 | 9 | 6 | 4 |
| Precip. % | 60 | 40 | 40 | 40 | 40 | 40 | 0 | 0 |
Tonight: Mainly cloudy with 60 percent chance of showers. Risk of a thunderstorm this evening. Wind west 20 km/h gusting to 40 becoming light this evening. Low 8.
Weather: Thetford Mines (local forecast), as of 2:03 a.m. EDT
Sun and moon
- Civil dawn
- 6:23 a.m.
- Sunrise
- 6:53 a.m.
- Sunset
- 6:09 p.m.
- Civil dusk
- 6:39 p.m.
- Moonrise
- 5:43 a.m.
- Moonset
- 5:27 p.m.
- Moon
- Waning crescent, 1% lit
Follow this lake by email: a weekly summary of conditions.
Depth
18% of Grand lac Saint-François is deeper than 20 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 1972 records a maximum depth of 39.8 m, drawn from 57 depth contours.
- Download the depth map (SVG)Printing this page gives the map on one sheet, with scale and sources.
- Official government depth map (PDF)
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 2009 and 2025; the latest annual mean is 2.6 m.
Photos
Follow this lake
Every Friday by email: the Environment Canada forecast and any weather alerts in effect.