Trout Lake

Where Trout Lake is

Trout Lake lies in the District of Sudbury, with shoreline in the Municipality of French River.

How deep is Trout Lake?

The deepest mapped contour on Trout Lake is 60.0 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 327 depth contours for Trout 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.

Trout Lake has 13 Lake Partner monitoring sites. Eight 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 5454/11 at Ranger Bay, with phosphorus sampled once a year over 18 years to 2025. Its long-term mean phosphorus concentration is 6.52 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 52 clarity readings at site 5454/11 give a median Secchi depth of 3.8 meters.

Median Secchi depth by year at site 5454/11

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

Fish in Trout Lake

Ontario’s aquatic resource records name 16 fish species in Trout Lake. The province’s other records for the lake name one further species, brook trout. It appears in the records below.

Popular species in the province’s records

• Lake Trouttrout and whitefish
• Ciscotrout and whitefish
• Northern Pikepike
• Muskellungepike
• Walleyeperch
• Yellow Perchperch
• Smallmouth Basssunfish
• Largemouth Basssunfish
• Rock Basssunfish
• Pumpkinseedsunfish

Spawning areas

Ontario maps 2 fish spawning records within the Trout Lake outline: 2 walleye spawning areas covering 14.68 hectares. Every record is recorded as verified and presently suitable, and none is classed as sensitive.

By number of records

By area mapped

• Walleye2 areas14.7 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 Trout Lake run from 1947 to 2015 and hold 63 releases. Walleye account for most of the fish: 900,241 released in eleven of the years between 1975 and 2015. The last recorded release was 10,200 walleye fingerlings in 2015.

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for six species taken from Trout Lake, tested for contaminants at a sampling location in Hoskin & Cherriman Twps., Sudbury 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

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

Fisheries management zones around Trout Lake

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

Trout Lake Ice Fishing

An ice hut on Trout Lake 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). Trout Lake 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 Trout 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

Islands and names

Trout Lake contains 37 islands in the Ontario Hydro Network’s outline, one of them over 10 hectares and nineteen under a tenth of a hectare. Big Island, at 28 hectares, is larger than the next ten together, which cover 22.

Official names

Ontario’s geographic names register lists 3 official names on the water and its islands: 3 islands.

Nearby lakes

• Nepewassi Lake17 km away
• Richard Lake36 km away
• Ramsey Lake41 km away
• Nepahwin Lake42 km away

All lakes

Questions about Trout Lake

• How deep is Trout Lake?

  Its deepest charted contour is 60 meters, and the water within it is deeper.

• How big is Trout Lake?

  Its surface covers 8.6 square kilometers and it holds 37 islands. Of its 80 kilometers of shoreline, 67 kilometers is the mainland shore and 13 kilometers is the shore of the islands.

• What fish are in Trout Lake?

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

• Is the water clear?

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