Lac Sir-John
45.7232° N, 74.2896° W
Depth contours from the 2014 government survey. Not for navigation.
Download the depth map (SVG)Lac Sir-John, Quebec. 45.7232° N, 74.2896° W
Maximum depth 21 m (2014 survey). Scale bar on the map.
Not for navigation. Depths are from government surveys and may be outdated.
borealbound.ca/lakes/qc/lac-sir-john/, 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).
- Air Quality Health Index observations and forecasts, Environment and Climate Change Canada. Contains data from Environment and Climate Change Canada (ECCC Data Servers End-use Licence).
Lac Sir-John is 21 m deep at its deepest point, deeper than 64% of the 1,506 surveyed lakes in Quebec. It covers 0.6 km² and lies 3.1 km south of Lakefield.
- Maximum depth
- 21 msurveyed 2014
- deeper than 64% of the 1,506 surveyed lakes in Quebec
- Area
- 0.6 km²
- larger than 65% of the 29,407 lakes in Quebec
- Shoreline
- 6.1 km
- longer than 67% of the 29,407 lakes in Quebec
- Water clarity
- 4.4 mSecchi depth, 2025
- clearer than 60% of the 805 monitored lakes in Quebec
- Elevation
- 184 m
Today on the water
6.3 °C
Observed at Lachute, as of 3:00 a.m. EDT
calm Estimated waves, next 12 hours: up to 0.1 m. Around 4 a.m., wind from the west: the west shore is sheltered, waves build toward the east shore.
| Time | 4 a.m. | 7 a.m. | 10 a.m. | 1 p.m. | 4 p.m. | 7 p.m. | 10 p.m. | 1 a.m. |
|---|---|---|---|---|---|---|---|---|
| Wind km/h | W 10 | W 10 | W 20 | W 20 | W 20 | W 20 | W 10 | W 10 |
| Gusts km/h | 40 | 40 | 40 | |||||
| Waves (est.) m | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | |||
| Temp. °C | 9 | 8 | 10 | 12 | 13 | 10 | 6 | 4 |
| Precip. % | 0 | 0 | 0 | 40 | 40 | 0 | 0 | 0 |
Tonight: Partly cloudy. 40 percent chance of showers this evening. Wind west 20 km/h gusting to 40 becoming light this evening. Low 8.
Weather: Lachute (local forecast), as of 3:02 a.m. EDT
Sun and moon
- Civil dawn
- 6:36 a.m.
- Sunrise
- 7:05 a.m.
- Sunset
- 6:22 p.m.
- Civil dusk
- 6:51 p.m.
- Moonrise
- 5:56 a.m.
- Moonset
- 5:40 p.m.
- Moon
- Waning crescent, 1% lit
Follow this lake by email: a weekly summary of conditions.
Depth
13% of Lac Sir-John is shallower than 3 m, and 51% 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 2014 records a maximum depth of 21 m, drawn from 14 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 4 years between 2008 and 2025; the latest annual mean is 4.4 m.
Follow this lake
Every Friday by email: the Environment Canada forecast and any weather alerts in effect.