McMahon Lake
46.5342° N, 83.8028° W
Depth contours from the 2025 government survey. Not for navigation.
Download the depth map (SVG)McMahon Lake, Ontario. 46.5342° N, 83.8028° W
Maximum depth 30 m (2025 survey). Scale bar on the map.
Not for navigation. Depths are from government surveys and may be outdated.
borealbound.ca/lakes/on/mcmahon-lake/, 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.
- Aquatic Resource Area survey points, Ontario Ministry of Natural Resources. Contains information licensed under the Open Government Licence – Ontario.
- Fish stocking for recreational purposes, Ontario Ministry of Natural Resources. Contains information licensed under the Open Government Licence – Ontario.
- Fishing access points, Ontario Ministry of Natural Resources. Contains information licensed under the Open Government Licence – Ontario.
- Fisheries Management Zones, Ontario Ministry of Natural Resources. Contains information licensed under the Open Government Licence – Ontario.
- Bathymetry lines and survey index, Ontario Ministry of Natural Resources. Contains information licensed under the Open Government Licence – Ontario.
- 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).
- Guide to Eating Ontario Fish: Advisory Database, Ontario Ministry of the Environment, Conservation and Parks. Contains information licensed under the Open Government Licence – Ontario.
McMahon Lake is 30 m deep at its deepest point, deeper than 78% of the 2,688 surveyed lakes in Ontario. It covers 2.25 km² and lies 4.5 km west of Poplar Dale.
Government surveys have recorded 11 fish species here, including lake whitefish, yellow perch and cisco.
- Maximum depth
- 30 msurveyed 2025
- deeper than 78% of the 2,688 surveyed lakes in Ontario
- Area
- 2.25 km²
- larger than 83% of the 18,731 lakes in Ontario
- Shoreline
- 16 km
- longer than 84% of the 18,731 lakes in Ontario
- Fish species
- 11
- more than 77% of the 2,454 surveyed lakes in Ontario
- Elevation
- 292 m
Today on the water
10.6 °C
Observed at Sault Ste. Marie, as of 6:00 a.m. EDT
choppy Estimated waves, next 12 hours: up to 0.2 m. Around 11 a.m., wind from the west: the west shore is sheltered, waves build toward the east shore.
| Time | 7 a.m. | 10 a.m. | 1 p.m. | 4 p.m. | 7 p.m. | 10 p.m. | 1 a.m. | 4 a.m. |
|---|---|---|---|---|---|---|---|---|
| Wind km/h | var. 5 | var. 5 | W 20 | W 20 | var. 5 | SE 10 | SE 10 | SE 10 |
| Gusts km/h | 40 | 40 | ||||||
| Waves (est.) m | 0.1 | 0.1 | 0.2 | 0.2 | 0.1 | |||
| Temp. °C | 10 | 11 | 12 | 13 | 11 | 8 | 4 | 6 |
| Precip. % | 10 | 10 | 0 | 0 | 0 | 0 | 0 | 0 |
Today: A mix of sun and cloud with 30 percent chance of showers early this morning. Becoming sunny this afternoon. Wind becoming west 20 km/h gusting to 40 late this morning. High 13. UV index 3 or moderate.
Weather: Sault Ste. Marie (local forecast), as of 6:03 a.m. EDT
Sun and moon
- Civil dawn
- 7:14 a.m.
- Sunrise
- 7:44 a.m.
- Sunset
- 6:59 p.m.
- Civil dusk
- 7:29 p.m.
- Moonrise
- 6:37 a.m.
- Moonset
- 6:18 p.m.
- Moon
- Waning crescent, 1% lit
Air Quality Health Index
1 low risk
Sault Ste. Marie, as of 5:00 a.m. EDT
Depth
8% of McMahon Lake is shallower than 3 m, and 71% 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 2025 records a maximum depth of 30 m, drawn from 68 depth contours.
- Download the depth map (SVG)Printing this page gives the map on one sheet, with scale and sources.
Not for navigation. Depths are from government surveys and may be outdated.
Fish
Sport fish by the share of the 20 government surveys (2008–2008) that recorded them.
Forage fish and other species (5)
Forage fish
- Common Shiner 5
- Golden Shiner 3
- Lake Chub 3
Other
- White Sucker 10
- Longnose Sucker 6
Numbers are the surveys that recorded each species.
Stocking
Lake Trout5,300 fish in 5 years, most recently 2024
All stocking records (5)
| Year | Species | Fish | Stage |
|---|---|---|---|
| 2024 | Lake Trout | 900 | Yearlings |
| 2022 | Lake Trout | 1,100 | Yearlings |
| 2020 | Lake Trout | 1,100 | Yearlings |
| 2018 | Lake Trout | 1,100 | Yearlings |
| 2016 | Lake Trout | 1,100 | Yearlings |
Eating your catch
The provincial guide to eating fish (2026) sets limits for 1 species from McMahon Lake. Maximum meals per month:
| Species | Length | General population | Sensitive population* | Contaminant |
|---|---|---|---|---|
| Lake Trout | 50-55 cm | 8 | 4 | PCB |
* As defined in the guide, including children and people who are or may become pregnant. Limits are for the length the guide lists most often; they change with the size of the fish. Read the official guide
Fishing regulations: Fisheries Management Zone 10. Check seasons and limits before you fish.
Getting on the water
1 listed access point.
- McMahon Lake Shoreline Access