Lake of Bays

Where Lake of Bays is

Lake of Bays lies in the District Municipality of Muskoka and the County of Haliburton, with shoreline in the Town of Huntsville, the Township of Lake of Bays and the Township of Algonquin Highlands.

How deep is Lake of Bays?

Lake of Bays reaches a maximum recorded depth of 79.2 meters, determined from 3,607 soundings taken during Ontario’s 1969 survey.

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 of Bays has 17 Lake Partner monitoring sites. Five 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 2469/12 at Little Trading Bay, with phosphorus sampled once a year over 12 years to 2021. Its long-term mean phosphorus concentration is 5.53 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 53 clarity readings at site 2469/12 give a median Secchi depth of 4.0 meters.

Median Secchi depth by year at site 2469/12

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

Lake of Bays Weather

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

Lake of Bays weather

Water temperature

Ontario’s aquatic resource records class Lake of Bays as a cold-water lake, with a mean depth of 22 meters against its maximum of 79.2.

A deep lake separates into layers through the summer. Sunlight and wind warm and mix the upper few meters, and beneath a band of rapid cooling, the thermocline, the water stays cold through the whole season. A mean depth of 22 meters places most of Lake of Bays’s volume in that cold layer, which is the condition lake trout and lake whitefish require.

No provincial monitoring station records water temperature on Lake of Bays. The weather page for Lake of Bays carries the LastLake model’s surface water temperature for each day of the coming week. The province’s longest in-water record is kept on eight research lakes near Dorset, sampled since 1976. A reading is taken at the surface, at one meter, at each meter to seven and then every two meters to the bottom, about every two weeks through the open-water season and about monthly under ice. The record holds 5,240 readings at a depth of one meter.

At one meter the eight lakes track one another closely. On a day when several were sampled, the warmest and the coolest lake differed by about one degree in every month of the year, and a 12 meter deep lake and a 37 meter deep lake read within 0.2 degrees of each other from June to October. The weather of the year, and not the lake, sets most of the width of the band below.

Water temperature at a depth of one meter (eight lakes near Dorset, ON)

How depth changes the temperature

The chart below is the province’s record on Harp Lake, 37 meters deep, drawn as the median temperature at each depth for each month over 49 years. In July the water at one meter is 23 degrees, at five meters 15, at seven meters 9, and from 13 meters to the bottom under 6. By October the warm layer has deepened to seven meters and cooled to 11 degrees. In February the whole column sits between 1 and 4 degrees under the ice, coldest at the top.

A shallower lake in the same record warms sooner. Heney Lake, six meters deep, reads about 1.8 degrees warmer than Harp Lake at one meter from January to May, 0.8 degrees warmer from June to August, and the same or cooler from September.

See also Lake Water Temperature in Ontario

Fish in Lake of Bays

Ontario’s aquatic resource records name 23 fish species in Lake of Bays. The province’s other records for the lake name two further species, brook trout and rainbow trout. They appear in the records below.

Popular species in the province’s records

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

Spawning areas

Ontario maps 73 fish spawning records within the Lake of Bays outline, for seven different species, and all of them are mapped below.

By number of records

By area mapped

• Lake Trout60 areas7.8 ha
• Northern Pike4 areas5.8 ha
• Rainbow Smelt3 areas500 m²
• Brook Trout nursery2 areas500 m²
• Brook Trout1 area0.3 ha
• Smallmouth Bass1 area0.3 ha
• Lake Whitefish1 area1.4 ha
• Sucker1 area0.7 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 of Bays run from 1946 to 1991 and hold 71 releases. Walleye account for most of the fish: 300,000 released in 1949. The last recorded release was 9,400 lake trout yearlings in 1991.

The province’s record of stocking for recreational fishing, kept from 2016, lists no release into Lake of Bays.

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for eight species taken from Lake of Bays, tested for contaminants at a sampling location in Muskoka D. M. 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 15

Lake of Bays lies in Fisheries Management Zone 15. Ontario sets its fishing seasons and catch limits by zone. The province describes it as a zone of many natural lake trout and brook trout lakes, with a well-developed road network and moderate angling effort.

Fisheries management zones around Lake of Bays

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

Lake of Bays Ice Fishing

An ice hut on Lake of Bays 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 of Bays lies within FMZ 15.

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 15 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 Out Date

The ice has been recorded leaving Lake of Bays at Haystack Bay in 81 springs between 1939 and 2019. The median date is April 23. The earliest recorded break-up is March 26 in 2012, and the latest is May 9 in 1956.

Across the 81 recorded springs the median date has moved by less than a day each decade.

The record was contributed by Peter J. Dillon, Ontario Ministry of the Environment to the Global Lake and River Ice Phenology Database. The record only holds the ice-out dates for Lake of Bays, and no ice-in date.

Ice out dates for 81 recorded springs between 1939 and 2019

Ice conditions

No public record reports the thickness or the condition of the ice on Lake of Bays 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

Getting on the water

Fourteen access marks are mapped on Lake of Bays.

See also Boat Launches on Ontario Lakes

Islands and names

Lake of Bays contains 30 islands in the Ontario Hydro Network’s outline, two of them over 10 hectares and four under a tenth of a hectare. Bigwin Island, at 224 hectares, is larger than the next ten together, which cover 107.

Official names

Ontario’s geographic names register lists 56 official names on the water and its islands: 26 islands, fourteen bays, three shoals, two rocks, two narrows and three rivers. A further 12 named points stand on the mainland shore.

Bays 14

• Burnt Island Bay
• Church Bay
• Dwight Bay
• Echo Bay
• Emerald Bay
• Haystack Bay
• Menominee Bay
• Portage Bay
• Rabbit Bay
• Rat Bay
• Ten Mile Bay
• Trading Bay
• Whiskey Bay
• Whitehouse Bay

Shoals and rocks 5

• Britannia Shoal
• Point Ideal Shoal
• Raynor Shoal
• Seagull Rock
• Turners Rock

Harbours, cuts and narrows 2

• Dorset Narrows
• The Narrows

Points on the shore 12

• Black Point
• Chevalier Point
• Clovelly Point
• Elizabeth Point
• Fox Point
• Joli Point
• Needler Point
• Norway Point
• Point Ideal
• Price Point
• Ronville Point
• Whiskey Point

Communities on the lake 2

• Dorset
• Dwight

Nearby lakes

• Raven Lake12 km away
• Peninsula Lake13 km away
• Oxtongue Lake14 km away
• Fairy Lake16 km away

All lakes

Questions about Lake of Bays

• How deep is Lake of Bays?

  Its maximum recorded depth is 79.2 meters, determined during Ontario’s 1969 survey.

• How big is Lake of Bays?

  Its surface covers 67.4 square kilometers and it holds 30 islands. Of its 191 kilometers of shoreline, 160 kilometers is the mainland shore and 31 kilometers is the shore of the islands.

• What fish are in Lake of Bays?

  Ontario’s aquatic resource records name 23 species, among them lake trout, walleye, smallmouth bass, largemouth bass, northern pike and lake whitefish. The lake’s spawning, consumption and stocking records also name brook trout and rainbow trout.

• Is the water clear?

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

• Is there a public boat launch?

  Records mark seven boat launches.