Lake Manitou

Where Lake Manitou is

Lake Manitou lies in the District of Manitoulin, with shoreline in the Township of Assiginack, the Township of Billings, the Municipality of Central Manitoulin and the Town of Northeastern Manitoulin and the Islands.

How deep is Lake Manitou?

The deepest mapped contour on Lake Manitou is 48.8 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 122 depth contours for Lake Manitou.

See also Ontario's Largest and Deepest Lakes

Surveyed Depths

Ontario has surveyed the depths of several thousand of its lakes over more than half a century. Later surveys were conducted by boat with satellite positioning and produced hundreds of thousands of soundings per lake. Earlier surveys were charted by running transects across the water and drawing depth contours by hand.

Water quality

Ontario’s Lake Partner Program is a volunteer monitoring network. Participants collect water samples for phosphorus analysis and measure water clarity through the summer with a Secchi disk. Most sites are sampled for phosphorus once a year, in spring, and some several times a year between spring and fall. Phosphorus in many lakes rises through the summer, so the two kinds of average are measured on different bases.

Phosphorus is the nutrient that controls how much algae a lake can grow. A lake with little phosphorus stays clear and supports cold-water fish such as lake trout. As phosphorus rises, algae increase, the water clouds, and oxygen in the deep water falls as the algae decay. The province classifies each monitoring site by its average phosphorus:

• Oligotrophic, below 10 micrograms per litre: clear water and low algae.
• Mesotrophic, from 10 to 20: moderately productive water, with more algae and weed growth than an oligotrophic lake but rarely a bloom.
• Eutrophic, above 20: nutrient-rich water, prone to algal blooms and low oxygen at depth.

Lake Manitou has 12 Lake Partner monitoring sites. Three have reported phosphorus for the three or more years the province requires before a status is assigned. All are classified oligotrophic.

The longest record is held by site 6451/2 at Stn 2, W-Moody Bay, with phosphorus sampled several times a year between spring and fall over 23 years to 2025. Its long-term mean phosphorus concentration is 8.01 micrograms per litre, within the oligotrophic band, which extends to 10.

A Secchi disk is a white or black-and-white plate lowered on a marked line until it disappears from view. The depth at which it vanishes is the Secchi depth, a direct measure of water clarity. Clearer water gives a deeper reading.

The 167 clarity readings at site 6451/2 give a median Secchi depth of 6.0 meters.

Median Secchi depth by year at site 6451/2

See also Lake Water Quality and Blue-Green Algae in Ontario

Lake Manitou Weather

The weather page for Lake Manitou carries the forecast over the water, wave heights across the lake, and the modelled water temperature.

Lake Manitou weather

Water temperature

Ontario’s aquatic resource records class Lake Manitou as a cold-water lake.

A lake separates into layers through the summer where it is deep enough. Sunlight and wind warm and mix the upper few meters, and beneath a band of rapid cooling, the thermocline, the water stays cold. A shallow lake mixes to the bottom instead and warms through, sooner in spring and later into autumn.

No provincial monitoring station records water temperature on Lake Manitou. The LastLake model computes the temperature of its surface water for each day from the daily mean air temperature at Environment Canada’s Gore Bay-Manitoulin climate station, 46 kilometers from the lake, or the next nearest station when its record is incomplete, and from the lake’s area of 10,644 hectares and its mean depth. The province’s records give no mean depth for Lake Manitou; the model uses 6.7 meters, estimated from the lake’s depth contours.

Each day’s figure carries the model’s typical error for that month on lakes of the same size. The figure in the chart below is the temperature near the surface, away from the shoreline. Bays, shallows and water deeper below the surface differ in temperature. Temperature is not measured when ice covers the lake. The weather page for Lake Manitou carries the model’s figures for the past weeks and the coming week.

See also Lake Water Temperature in Ontario

Fish in Lake Manitou

Ontario’s aquatic resource records name 31 fish species in Lake Manitou. The province’s other records for the lake name one further species, rainbow trout. It appears in the records below.

Popular species in the province’s records

• Lake Trouttrout and whitefish
• Brook Trouttrout and whitefish
• Rainbow Trouttrout and whitefish
• Lake Whitefishtrout and whitefish
• Ciscotrout and whitefish
• Northern Pikepike
• Walleyeperch
• Yellow Perchperch
• Smallmouth Basssunfish
• Rock Basssunfish
• Pumpkinseedsunfish
• Burbotcod
• Brown Bullheadcatfish

Spawning areas

Ontario maps 2 fish spawning records within the Lake Manitou outline: 2 northern pike spawning areas covering 8.2 hectares.

By number of records

By area mapped

• Northern Pike2 areas8.2 ha

The federal Fisheries Act prohibits the harmful alteration, disruption or destruction of fish habitat without an authorization, so a dock, dredging, infill or shoreline work at a mapped spawning area is reviewed on that basis.

Stocking history

Ontario’s stocking records for Lake Manitou run from 1946 to 2015 and hold 283 releases. Lake Trout account for most of the fish: 2,755,578 released in 60 of the years between 1947 and 2015. The last recorded release was 9,280 lake trout yearlings in 2015.

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for nine species taken from Lake Manitou, tested for contaminants at a sampling location in Sandfield Twp., Manitoulin Dist. Each figure below is the most meals a month the guide advises for a fish of that length. Where mercury sets the advice, the figure falls as the fish gets longer, because mercury accumulates over a fish’s life. Where the guide has no result yet for certain contaminants at a location, it sets a precautionary limit of 16 meals a month. A zero means the guide advises no meals of that fish at that size.

General population: adultsSensitive population: children under fifteen, women who are or may become pregnant

Fisheries Management Zone 10

Lake Manitou lies in Fisheries Management Zone 10. Ontario sets its fishing seasons and catch limits by zone.

Fisheries management zones around Lake Manitou

Where a row reads zone-wide, the zone’s own season or limit above applies.

See also Fishing Seasons in Ontario, Zone by Zone and Fish Stocking in Ontario Lakes

Lake Manitou Ice Fishing

An ice hut on Lake Manitou must be removed by March 31. The province sets dates for ice hut removal as a safety measure to ensure huts are removed before thawing occurs. One date applies to an entire fisheries management zone (FMZ). Lake Manitou lies within FMZ 10.

An ice hut must also be removed before the ice breaks up, whether or not that date has passed. The deadline clears huts from the ice ahead of the thaw and does not close the fishing season.

Registration is required in FMZ 10 for an ice hut built of anything other than fabric, and for a fabric tent covering seven square meters or more. Registration is free, and the number is displayed on the outside of the hut.

Ice conditions

No public record reports the thickness or the condition of the ice on Lake Manitou on any given day. Ontario publishes ice safety guidance for anyone going out on the ice, at ontario.ca.

See also Lake Ice in Ontario and When the Lakes Will Freeze This Winter

Islands and names

Lake Manitou contains 25 islands in the Ontario Hydro Network’s outline, zero of them over 10 hectares and fourteen under a tenth of a hectare.

Official names

Ontario’s geographic names register lists 59 official names on the water and its islands: 13 islands, 30 bays, two shoals, one rock, one narrows and nine points on islands. A further 11 named points stand on the mainland shore.

Bays 30

• Bass Bay
• Bass Creek Bay
• Bathouse Bay
• Ben's Bay
• Bragmore Bay
• Cannard's Bay
• Cape Horn Bay
• Dawes Bay
• Dick's Bay
• Eagle's Nest Bay
• Gibraltar Bay
• Green Bay
• Jump's Bay
• Kotcamp's Bay
• Martin's Bay
• Moody Bay
• Newby's Bay
• Sandfield Bay
• Sandy Bay
• Schut's Bay
• Shearpin Bay
• Shirley's Bay
• Sidney Cox Bay
• Silver Bay
• Surecatch Bay
• Tilson's Bay
• Timberlane Bay
• Turtle Creek Bay
• Watson Bay
• Wee Point Bay

Shoals and rocks 3

• Acre Shoal
• Copper Rock
• Roper's Shoal

Harbours, cuts and narrows 1

• The Narrows

Points on the shore 11

• Brennan's Point
• Cape Horn Point
• Clark's Point
• Grable's Point
• King's Point
• Lone Star Point
• Long Point
• Maple Point
• Maple Rock Point
• Paul's Point
• Watson Point

Nearby lakes

• Mindemoya Lake17 km away
• Lake Kagawong25 km away
• Lake Wolsey42 km away
• Agnew Lake67 km away

All lakes

Questions about Lake Manitou

• How deep is Lake Manitou?

  Its deepest charted contour is 48.8 meters, and the water within it is deeper.

• How big is Lake Manitou?

  Its surface covers 106.5 square kilometers and it holds 25 islands. Of its 120 kilometers of shoreline, 113 kilometers is the mainland shore and 7 kilometers is the shore of the islands.

• What fish are in Lake Manitou?

  Ontario’s aquatic resource records name 31 species, among them lake trout, walleye, smallmouth bass, northern pike, lake whitefish and yellow perch. The lake’s spawning, consumption and stocking records also name rainbow trout.

• Is the water clear?

  All three monitoring sites with a phosphorus status are classified oligotrophic, the clearest of the province’s three bands.