Charleston Lake

Where Charleston Lake is

Charleston Lake lies in the United Counties of Leeds and Grenville, with shoreline in the Township of Athens and the Township of Leeds and the Thousand Islands.

How deep is Charleston Lake?

Charleston Lake reaches a maximum recorded depth of 92.0 meters, determined from 165,198 soundings taken during Ontario’s 2004 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.

Charleston Lake has 11 Lake Partner monitoring sites. Seven have reported phosphorus for the three or more years the province requires before a status is assigned. Two of those sites are classified oligotrophic and five mesotrophic.

The longest record is held by site 822/1 at Big Water, with phosphorus sampled several times a year between spring and fall over 23 years to 2025. Its long-term mean phosphorus concentration is 10.13 micrograms per litre, within the mesotrophic band, which runs from 10 to 20.

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 140 clarity readings at site 822/1 give a median Secchi depth of 6.0 meters.

Median Secchi depth by year at site 822/1

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

Charleston Lake Weather

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

Charleston Lake weather

Water temperature

Ontario’s aquatic resource records class Charleston Lake as a cold-water lake, with a mean depth of 17.4 meters against its maximum of 92.

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 17.4 meters places most of Charleston Lake’s volume in that cold layer, which is the condition lake trout and lake whitefish require.

No provincial monitoring station records water temperature on Charleston Lake. The LastLake model computes the temperature of its surface water for each day from the daily mean air temperature at Environment Canada’s Grenadier Island climate station, 18 kilometers from the lake, or the next nearest station when its record is incomplete, and from the lake’s area of 2,641 hectares and its mean depth of 17.4 meters.

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 Charleston Lake carries the model’s figures for the past weeks and the coming week.

See also Lake Water Temperature in Ontario

Fish in Charleston Lake

Ontario’s aquatic resource records name 31 fish species in Charleston Lake.

Popular species in the province’s records

• Lake Trouttrout and whitefish
• Lake Whitefishtrout and whitefish
• Ciscotrout and whitefish
• Northern Pikepike
• Yellow Perchperch
• Smallmouth Basssunfish
• Largemouth Basssunfish
• Black Crappiesunfish
• Rock Basssunfish
• Pumpkinseedsunfish
• Bluegillsunfish
• Burbotcod
• Brown Bullheadcatfish

Spawning areas

Ontario maps 349 fish spawning records within the Charleston Lake outline, for nine different species, and all of them are mapped below.

By number of records

By area mapped

• Smallmouth Bass111 areas36.2 ha
• Largemouth Bass74 areas18.1 ha
• Yellow Perch66 areas15.4 ha
• Northern Pike62 areas14.4 ha
• Lake Trout24 areas4.6 ha
• Brown Bullhead5 areas2.4 ha
• Pumpkinseed4 areas1.3 ha
• Black Crappie2 areas0.6 ha
• Lake Whitefish1 area200 m²

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 Charleston Lake run from 1947 to 2011 and hold 113 releases. Lake Trout account for most of the fish: 850,673 released in 57 of the years between 1947 and 2011. The last recorded release was 5,720 lake trout yearlings in 2011.

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

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for ten species taken from Charleston Lake, tested for contaminants at a sampling location in Leeds & Lansdowne Twps. 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 18

Charleston Lake lies in Fisheries Management Zone 18. Ontario sets its fishing seasons and catch limits by zone.

Fisheries management zones around Charleston Lake

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

Charleston Lake Ice Fishing

An ice hut on Charleston Lake must be removed by March 15. 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). Charleston Lake lies within FMZ 18.

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 18 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 Charleston Lake 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

Nine access marks are mapped on Charleston Lake.

See also Boat Launches on Ontario Lakes

Islands and names

Charleston Lake contains 152 islands in the Ontario Hydro Network’s outline, eight of them over 10 hectares and 57 under a tenth of a hectare. Eight of them lie mostly inside wetland the province’s Wetland With Significance dataset maps as marsh or unclassified wetland.

Official names

Ontario’s geographic names register lists 173 official names on the water and its islands: 104 islands, 29 bays, two rocks, one narrows and fifteen points on islands. A further 22 named points stand on the mainland shore.

Bays 29

• Black Hole Bay
• Dixons Bay
• Donaldson Bay
• Four Corners Water
• Gailies Bay
• Gavins Bay
• Grassy Bay
• Greens Bay
• Hay Bay
• Huckleberry Hollow Bay
• La Rose Bay
• Larkin Bay
• Loon Bay
• Mud Bay
• Mud Bay
• Nest Bay
• Oswego Bay
• Runnings Bay
• Sallys Hole
• Sand Bay
• Sapbush Bay
• Shad Bay
• Slacks Bay
• Slim Bay
• Sunset Bay
• Tallow Rock Bay
• Warren Bay
• Waterlily Bay
• Webster Bay

Shoals and rocks 2

• Eagle Rock
• Tallow Rock

Harbours, cuts and narrows 1

• The Narrows

Points on the shore 22

• Angel Point
• Blogget Point
• Bowsprit Point
• Buckhorn Point
• Butternut Point
• Cedar Grove Point
• Crawford Point
• Dead Horse Point
• Derbyshire Point
• Donaldson Point
• Greers Point
• Jacksons Point
• Justus Point
• Lone Fisherman Point
• Lookout Point
• Medoles Point
• Peggys Point
• Sand Bay Point
• Slacks Point
• White Birch Point
• White Sheep Point
• Yardarm Point

Communities on the lake 3

• Charleston
• Outlet
• Beales Mills

Nearby lakes

• Red Horse Lake5 km away
• Upper Beverley Lake11 km away
• Whitefish Lake16 km away
• Sand Lake19 km away

All lakes

Questions about Charleston Lake

• How deep is Charleston Lake?

  Its maximum recorded depth is 92 meters, determined during Ontario’s 2004 survey.

• How big is Charleston Lake?

  Its surface covers 26.4 square kilometers and it holds 152 islands. Of its 179 kilometers of shoreline, 94 kilometers is the mainland shore and 85 kilometers is the shore of the islands.

• What fish are in Charleston Lake?

  Ontario’s aquatic resource records name 31 species, among them lake trout, smallmouth bass, largemouth bass, northern pike, lake whitefish and yellow perch.

• Is there a public boat launch?

  Records mark three boat launches.