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.

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.

Lake of Bays Aerial Photography

Ontario photographs the province from the air on a rolling schedule.

The photograph below is from the SCOOP2023 collection, flown in 2023 and 2024.

Water quality

Ontario’s Lake Partner Program is a volunteer monitoring network. Participants collect a water sample each spring for phosphorus analysis and measure water clarity through the summer with a Secchi disk.

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 spring phosphorus. Below 10 micrograms per litre is oligotrophic: clear water and low algae. From 10 to 20 is mesotrophic: moderately productive water, with more algae and weed growth than an oligotrophic lake but rarely a bloom. Above 20 is eutrophic: nutrient-rich water, prone to algal blooms and low oxygen at depth.

A Secchi disk is a 20 centimeter 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.

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, sampled over 12 springs to 2021. Its long-term mean phosphorus concentration is 5.53 micrograms per litre, within the oligotrophic band, which extends to 10. The site’s 53 clarity readings give a median Secchi depth of 4.0 meters.

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 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.

Satellite thermal imagery gives a surface reading on clear days: the Landsat sensors pass over Lake of Bays every eight days at a resolution of 100 meters. In the province’s record the surface reading and the one meter reading agree to within half a degree nine times in ten in summer.

The water a few meters down is colder than any figure on this chart, in every month of the year.

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.

Fish in Lake of Bays

Ontario’s aquatic resource records name 23 fish species in Lake of Bays. The province classes the lake as cold water. The record took effect on 23 September 2016, and it compiles what field biologists had reported by then. The province’s other records for the lake name two further species, brook trout and rainbow trout. They appear in the records below.

Thirteen of the 25 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 species, all of them mapped areas.

By number of records

By area mapped

• Lake Trout60 areas7.8 ha
• Northern Pike4 areas6.0 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 one of the years between 1949 and 1949. The last recorded release was 9,400 lake trout yearlings in 1991.

The province’s current stocking programme, recorded from 2016, lists no release into Lake of Bays.

Eating the fish

The 2025 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. The advice falls as the fish gets longer, because mercury accumulates over a fish’s life. 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. Zone 15 covers central Ontario from Georgian Bay to the Ottawa River, bounded to the north by the Pickerel River, Highway 522 and the northern edge of Algonquin Park. It takes in Parry Sound, Huntsville, Bracebridge, Bancroft, Pembroke and Renfrew, and the whole of Algonquin Provincial Park. 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.

The figures are the number of fish an angler may catch and keep in a day and have in possession, under a sport fishing licence and under a conservation licence. The rows are the whole zone’s, and they apply to every lake in it. No waterbody exception names Lake of Bays.

Lake of Bays Ice Fishing

An ice hut on Lake of Bays must be removed by March 31. Lake of Bays lies in fisheries management zone 15, one of the twenty zones Ontario sets its fishing rules by, and one removal date applies across the whole zone.

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 zone 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.

When the ice goes out

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. It holds the day the ice left and carries no date for the day it formed, so it says nothing about when Lake of Bays freezes.

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.

Getting on the water

Fourteen access marks are mapped on Lake of Bays: seven boat launches, one enhanced shoreline access point, two shoreline access points, three marinas and one beach. Eleven are Ontario’s own records and three are from the Overture Places dataset, and the list under the map says which is which. Boat launch is the province’s class for a ramp; enhanced shoreline access and shoreline access are its classes for a place the public can reach the water on foot.

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. The register records the origin of two names.

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

• Peninsula Lake13 km away
• Oxtongue Lake14 km away
• Fairy Lake16 km away
• St. Nora Lake17 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, one enhanced shoreline access point, two shoreline access points, three marinas and one beach on Lake of Bays.