Malachi Lake

Where Malachi Lake is

Malachi Lake lies in the District of Kenora.

How deep is Malachi Lake?

The deepest mapped contour on Malachi Lake is 18.3 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 23 depth contours for Malachi 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.

Malachi Lake has 8 Lake Partner monitoring sites. Six have reported phosphorus for the three or more years the province requires before a status is assigned. All are classified mesotrophic.

The longest record is held by site 2959/1 at Copeland's Bay, with phosphorus sampled once a year over 21 years to 2025. Its long-term mean phosphorus concentration is 18.95 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 298 clarity readings at site 2959/1 give a median Secchi depth of 3.3 meters.

Median Secchi depth by year at site 2959/1

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

Fish in Malachi Lake

Ontario’s aquatic resource records name 10 fish species in Malachi Lake.

Popular species in the province’s records

• Ciscotrout and whitefish
• Northern Pikepike
• Walleyeperch
• Yellow Perchperch
• Smallmouth Basssunfish

Spawning areas

Ontario maps 6 fish spawning records within the Malachi Lake outline: 6 walleye spawning areas covering 3.88 hectares.

By number of records

By area mapped

• Walleye6 areas3.9 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 Malachi Lake run from 1949 to 1949 and hold 1 release. Walleye account for most of the fish: 400,000 released in 1949. The last recorded release was 400,000 walleye frys in 1949.

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

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for three species taken from Malachi Lake, tested for contaminants at a sampling location in Malachi & Rudd Twps., Kenora 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 5

Malachi Lake lies in Fisheries Management Zone 5. Ontario sets its fishing seasons and catch limits by zone.

Fisheries management zones around Malachi Lake

Zone-wide, Smelt may not be used as bait or possessed for use as bait.

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

Islands and names

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

Nearby lakes

• Longpine Lake14 km away
• Lake Lulu26 km away
• Black Sturgeon Lakes41 km away
• Lake of the Woods75 km away

All lakes

Questions about Malachi Lake

• How deep is Malachi Lake?

  Its deepest charted contour is 18.3 meters, and the water within it is deeper.

• How big is Malachi Lake?

  Its surface covers 10.8 square kilometers and it holds 8 islands. Of its 43 kilometers of shoreline, 36 kilometers is the mainland shore and 7 kilometers is the shore of the islands.

• What fish are in Malachi Lake?

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

• Is the water clear?

  All six monitoring sites with a phosphorus status are classified mesotrophic, the middle of the province’s three bands.