Dalhousie Lake

Where Dalhousie Lake is

Dalhousie Lake lies in the County of Lanark, within the Township of Lanark Highlands.

How deep is Dalhousie Lake?

Dalhousie Lake reaches a maximum recorded depth of 18.8 meters, determined from 21,277 soundings.

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.

Dalhousie Lake has 1 Lake Partner monitoring site, which has yet reported phosphorus for the three years the province requires before a status is assigned.

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.

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

Dalhousie Lake Weather

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

Dalhousie Lake weather

Water temperature

No provincial monitoring station records water temperature on Dalhousie Lake. The LastLake model computes the temperature of its surface water for each day from the daily mean air temperature at Environment Canada’s Appleton climate station, 44 kilometers from the lake, or the next nearest station when its record is incomplete, and from the lake’s area of 615 hectares and its mean depth of 5.2 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 Dalhousie Lake carries the model’s figures for the past weeks and the coming week.

See also Lake Water Temperature in Ontario

Fish in Dalhousie Lake

Ontario’s aquatic resource records name 28 fish species in Dalhousie Lake.

Popular species in the province’s records

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

Spawning areas

Ontario maps 3 fish spawning records within the Dalhousie Lake outline, for two different species, and all of them are mapped below. Every record is recorded as verified and presently suitable, and none is classed as sensitive.

By number of records

By area mapped

• Smallmouth Bass2 areas2.2 ha
• Northern Pike1 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 Dalhousie Lake run from 1946 to 1991 and hold 51 releases. Walleye account for most of the fish: 11,032,052 released in 21 of the years between 1946 and 1991. The last recorded release was 8,377 walleye fingerlings in 1991.

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

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for six species taken from Dalhousie Lake, tested for contaminants at a sampling location in Dalhousie Twp., Lanark 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

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

Fisheries management zones around Dalhousie Lake

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

Dalhousie Lake Ice Fishing

An ice hut on Dalhousie 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). Dalhousie 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 Dalhousie 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

Official names

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

Nearby lakes

• Silver Lake16 km away
• Crotch Lake20 km away
• Christie Lake21 km away
• Palmerston Lake23 km away

All lakes

Questions about Dalhousie Lake

• How deep is Dalhousie Lake?

  Its maximum recorded depth is 18.8 meters.

• How big is Dalhousie Lake?

  Its surface covers 6.2 square kilometers, with 16 kilometers of shoreline.

• What fish are in Dalhousie Lake?

  Ontario’s aquatic resource records name 28 species, among them walleye, smallmouth bass, largemouth bass, northern pike, lake whitefish and yellow perch.