Grand lac Long
46.5407° N, 72.9501° W
Depth contours from the 1976 government survey. Not for navigation.
Download the depth map (SVG)Grand lac Long, Quebec. 46.5407° N, 72.9501° W
Maximum depth 31.6 m (1976 survey). Scale bar on the map.
Not for navigation. Depths are from government surveys and may be outdated.
borealbound.ca/lakes/qc/grand-lac-long/, 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 Long is 31.6 m deep at its deepest point, deeper than 83% of the 1,506 surveyed lakes in Quebec. It covers 0.75 km² and lies 3 km north of Domaine-Saint-Paulin.
- Maximum depth
- 31.6 msurveyed 1976
- deeper than 83% of the 1,506 surveyed lakes in Quebec
- Area
- 0.75 km²
- larger than 70% of the 29,407 lakes in Quebec
- Shoreline
- 7.2 km
- longer than 71% of the 29,407 lakes in Quebec
- Water clarity
- 6.6 mSecchi depth, 2025
- clearer than 90% of the 805 monitored lakes in Quebec
- Elevation
- 176 m
Today on the water
YELLOW ADVISORY - FROST · issued 11:25 a.m. EDT
Temperatures will drop to near freezing 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 3:25 a.m. EDT Saturday
11 °C
Observed at Shawinigan, as of 12:00 p.m. EDT
choppy Estimated waves, next 12 hours: up to 0.2 m. Around 6 p.m., wind from the northwest: the northwest shore is sheltered, waves build toward the southeast shore.
| Time | 1 p.m. | 4 p.m. | 7 p.m. | 10 p.m. | 1 a.m. | 4 a.m. | 7 a.m. | 10 a.m. |
|---|---|---|---|---|---|---|---|---|
| Wind km/h | W 20 | W 20 | NW 20 | NW 15 | NW 10 | NW 10 | NW 10 | NW 10 |
| Gusts km/h | 40 | 40 | ||||||
| Waves (est.) m | 0.1 | 0.1 | 0.2 | 0.1 | ||||
| Temp. °C | 11 | 11 | 10 | 8 | 6 | 5 | 2 | 6 |
| Precip. % | 30 | 30 | 0 | 0 | 0 | 0 | 0 | 0 |
Today: A mix of sun and cloud with 30 percent chance of showers. Wind west 20 km/h gusting to 40. High 12. UV index 3 or moderate.
Weather: Shawinigan (local forecast), as of 12:02 p.m. EDT
Sun and moon
- Civil dawn
- 6:30 a.m.
- Sunrise
- 7:01 a.m.
- Sunset
- 6:16 p.m.
- Civil dusk
- 6:46 p.m.
- Moonrise
- 5:51 a.m.
- Moonset
- 5:34 p.m.
- Moon
- Waning crescent, 1% lit
Depth
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 1976 records a maximum depth of 31.6 m, drawn from 21 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: oligotrophic.
Clarity was measured with a Secchi disk in 18 years between 2008 and 2025; the latest annual mean is 6.6 m.