Basswood Lake

Where Basswood Lake is

Basswood Lake lies in the District of Algoma, within the Municipality of Huron Shores.

How deep is Basswood Lake?

The deepest mapped contour on Basswood Lake is 73.2 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 35 depth contours for Basswood 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.

Basswood Lake has 2 Lake Partner monitoring sites. Two 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 246/1 at East basin, deep spot, with phosphorus sampled once a year over 18 years to 2025. Its long-term mean phosphorus concentration is 2.81 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 146 clarity readings at site 246/1 give a median Secchi depth of 11.5 meters.

Median Secchi depth by year at site 246/1

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

Basswood Lake Weather

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

Basswood Lake weather

Water temperature

Ontario’s aquatic resource records class Basswood Lake as a cold-water lake, with a mean depth of 38.7 meters against its maximum of 73.2.

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 38.7 meters places most of Basswood 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 Basswood Lake. The LastLake model computes the temperature of its surface water for each day from the daily mean air temperature at Environment Canada’s Gore Bay Climate climate station, 80 kilometers from the lake, or the next nearest station when its record is incomplete, and from the lake’s area of 2,712 hectares and its mean depth of 38.7 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 Basswood Lake carries the model’s figures for the past weeks and the coming week.

See also Lake Water Temperature in Ontario

Fish in Basswood Lake

Ontario’s aquatic resource records name 23 fish species in Basswood Lake.

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
• Rock Basssunfish
• Burbotcod
• Brown Bullheadcatfish

Spawning areas

Ontario maps 4 fish spawning records within the Basswood Lake outline: 4 lake trout spawning areas covering 4.52 hectares.

By number of records

By area mapped

• Lake Trout4 areas4.5 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 Basswood Lake run from 1946 to 1969 and hold 21 releases. Walleye account for most of the fish: 1,300,000 released in three of the years between 1946 and 1950. The last recorded release was 2,101 lake trout juvenile/adults in 1969.

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

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for two species taken from Basswood Lake, tested for contaminants at a sampling location in Day Twp., Algoma 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. 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

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

Fisheries management zones around Basswood Lake

Where a row reads zone-wide, the zone’s own season or limit above applies.

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

Basswood Lake Ice Fishing

An ice hut on Basswood 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). Basswood 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 Basswood 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

Basswood Lake contains five islands in the Ontario Hydro Network’s outline, zero of them over 10 hectares and two under a tenth of a hectare.

Official names

Ontario’s geographic names register lists 4 official names on the water and its islands: 1 island and two bays.

Bays 2

• Boyles Bay
• Phillips Bay

Nearby lakes

• Chiblow Lake27 km away
• Matinenda Lake35 km away
• Lauzon Lake47 km away
• Ranger Lake66 km away

All lakes

Questions about Basswood Lake

• How deep is Basswood Lake?

  Its deepest charted contour is 73.2 meters, and the water within it is deeper.

• How big is Basswood Lake?

  Its surface covers 27.1 square kilometers and it holds 5 islands. Of its 51 kilometers of shoreline, 48 kilometers is the mainland shore and 3 kilometers is the shore of the islands.

• What fish are in Basswood Lake?

  Ontario’s aquatic resource records name 23 species, among them lake trout, walleye, smallmouth bass, northern pike, lake whitefish and yellow perch.

• Is the water clear?

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