Map of Lac Joseph with depth contours

Lac Joseph

46.2049° N, 71.5494° W

Depth contours from the 1963 government survey. Not for navigation.

Download the depth map (SVG)

Lac Joseph is 5.3 m deep at its deepest point, shallower than 92% of the 1,506 surveyed lakes in Quebec. It covers 2.42 km² and lies 4.5 km north of Lac-William.

Maximum depth
5.3 msurveyed 1963
shallower than 92% of the 1,506 surveyed lakes in Quebec
Area
2.42 km²
larger than 85% of the 29,407 lakes in Quebec
Shoreline
17.8 km
longer than 87% of the 29,407 lakes in Quebec
Water clarity
1.4 mSecchi depth, 2025
less clear than 95% of the 805 monitored lakes in Quebec
Elevation
192 m

Today on the water

4.8 °C

Wind SW 9 km/h

Observed at Thetford Mines, 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.

Hourly forecast, next 24 hours
Time4 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/hW 10W 10W 20W 20W 20W 20W 15W 10
Gusts km/h404040
Waves (est.) m0.10.10.10.10.1
Temp. °C9891110753
Precip. %60404040404000

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 3:02 a.m. EDT

Sun and moon

Civil dawn
6:25 a.m.
Sunrise
6:55 a.m.
Sunset
6:10 p.m.
Civil dusk
6:40 p.m.
Moonrise
5:45 a.m.
Moonset
5:28 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

36% of Lac Joseph is shallower than 1 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 1963 records a maximum depth of 5.3 m, drawn from 8 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 Depths are from government surveys and may be outdated.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 21 years between 2004 and 2025; the latest annual mean is 1.4 m.

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

Photos

Lac Joseph - Rivière Bécancour (2)
Photo: Gabriel Picard, CC BY-SA 4.0, via Wikimedia Commons