Big Gull Lake

Where Big Gull Lake is

Big Gull Lake lies in the County of Frontenac, with shoreline in the Township of North Frontenac and the Township of Central Frontenac.

How deep is Big Gull Lake?

The deepest mapped contour on Big Gull Lake is 24.4 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 66 depth contours for Big Gull Lake.

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.

Big Gull Lake has 5 Lake Partner monitoring sites. Four 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 two mesotrophic.

The longest record is held by site 373/3 at Pinnacle Point, with phosphorus sampled once a year over 24 years to 2025. Its long-term mean phosphorus concentration is 8.92 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 232 clarity readings at site 373/3 give a median Secchi depth of 4.3 meters.

Median Secchi depth by year at site 373/3

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

Big Gull Lake Weather

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

Big Gull Lake weather

Water temperature

Ontario’s aquatic resource records class Big Gull Lake as a cool-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 Big Gull Lake. The LastLake model computes the temperature of its surface water for each day from the daily mean air temperature at Environment Canada’s Centreville climate station, 48 kilometers from the lake, or the next nearest station when its record is incomplete, and from the lake’s area of 2,469 hectares and its mean depth. The province’s records give no mean depth for Big Gull Lake; the model uses 6.8 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 Big Gull Lake carries the model’s figures for the past weeks and the coming week.

See also Lake Water Temperature in Ontario

Fish in Big Gull Lake

Ontario’s aquatic resource records name 24 fish species in Big Gull Lake. The province’s other records for the lake name one further species, lake trout. It appears in the records below.

Popular species in the province’s records

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

Spawning areas

Ontario maps 73 fish spawning records within the Big Gull Lake outline: 73 walleye spawning areas covering 3.99 hectares.

By number of records

By area mapped

• Walleye73 areas4.0 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 Big Gull Lake run from 1946 to 1989 and hold 68 releases. Walleye account for most of the fish: 8,145,000 released in ten of the years between 1946 and 1989. The last recorded release was 345,000 walleye frys in 1989.

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

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for ten species taken from Big Gull Lake, tested for contaminants at a sampling location in Barrie, Clarendon & Kennebec Twps., Frontenac Co. 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

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

Fisheries management zones around Big Gull Lake

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

Big Gull Lake Ice Fishing

An ice hut on Big Gull 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). Big Gull 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 Big Gull 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

Islands and names

Big Gull Lake contains 154 islands in the Ontario Hydro Network’s outline, three of them over 10 hectares and 92 under a tenth of a hectare. Seven of them lie mostly inside wetland the province’s Wetland With Significance dataset maps as unclassified wetland. Long Island, at 89 hectares, is larger than the next ten together, which cover 64.

Official names

Ontario’s geographic names register lists 24 official names on the water and its islands: 19 islands and three bays.

Bays 3

• Earls Bay
• East Bay
• Watkin Bay

Nearby lakes

• Kashwakamak Lake7 km away
• Kennebec Lake12 km away
• Crotch Lake14 km away
• Buckshot Lake21 km away

All lakes

Questions about Big Gull Lake

• How deep is Big Gull Lake?

  Its deepest charted contour is 24.4 meters, and the water within it is deeper.

• How big is Big Gull Lake?

  Its surface covers 24.7 square kilometers and it holds 154 islands. Of its 168 kilometers of shoreline, 117 kilometers is the mainland shore and 51 kilometers is the shore of the islands.

• What fish are in Big Gull Lake?

  Ontario’s aquatic resource records name 24 species, among them walleye, smallmouth bass, largemouth bass, northern pike, muskellunge and lake whitefish. The lake’s spawning, consumption and stocking records also name lake trout.