Lac Seul

Where Lac Seul is

Lac Seul lies in the District of Kenora, with shoreline in the Township of Ear Falls.

How deep is Lac Seul?

The deepest mapped contour on Lac Seul is 36.6 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 1,153 depth contours for Lac Seul.

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.

No monitoring site on Lac Seul is registered with the Lake Partner Program, so no phosphorus or clarity record exists for the lake.

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

Fish in Lac Seul

Ontario’s aquatic resource records list no species for Lac Seul. The province’s other records for the lake name twelve species, among them walleye, northern pike and muskellunge. They appear in the records below.

Popular species in the province’s records

• Lake Whitefishtrout and whitefish
• Ciscotrout and whitefish
• Northern Pikepike
• Muskellungepike
• Walleyeperch
• Saugerperch
• Yellow Perchperch
• Smallmouth Basssunfish
• Burbotcod

Spawning areas

Ontario maps 23 fish spawning records within the Lac Seul outline, for three different species, and all of them are mapped below.

By number of records

By area mapped

• Walleye13 areas460.3 ha
• Northern Pike6 areas59.0 ha
• Muskellunge4 areas37.3 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 Lac Seul run from 1946 to 1961 and hold 27 releases. Lake Whitefish account for most of the fish: 22,000,000 released in twelve of the years between 1946 and 1961. The last recorded release was 2,000,000 walleye eggs in 1961.

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

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for ten species taken from Lac Seul, tested for contaminants at a sampling location in 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. 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 4

Lac Seul lies in Fisheries Management Zone 4. Ontario sets its fishing seasons and catch limits by zone.

Fisheries management zones around Lac Seul

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

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

Islands and names

Lac Seul contains 1,488 islands in the Ontario Hydro Network’s outline, 148 of them over 10 hectares and 423 under a tenth of a hectare. Eight of them lie mostly inside wetland the province’s Wetland With Significance dataset maps as marsh or fen. The largest of these, at 4.5 hectares, falls inside the GOLDPINES WETLAND.

Official names

Ontario’s geographic names register lists 100 official names on the water and its islands: 26 islands, 36 bays, ten narrows, one point on an island and three rivers. A further 12 named points stand on the mainland shore.

Bays 36

• Aldous Bay
• Anenimus Bay
• Bannatyne Bay
• Bay of Islands
• Black Bay
• Bray Bay
• Brechin Bay
• Burntwood Bay
• Canoe Bay
• Coones Bay
• Deception Bay
• Farewell Bay
• Fish Hook Bay
• Goose Bay
• Gynane Bay
• Kejick Bay
• Lower Grassy Bay
• McIntyre Bay
• McKenzie Bay
• Merritt Bay
• Ningewance Bay
• Picnic Bay
• Quirt Bay
• Rat Bay
• Route Bay
• Sawmill Bay
• Scout Bay
• Sen Bay
• South Bay
• Tuktegweik Bay
• Two Point Bay
• Vallance Bay
• Victor Bay
• Wapesi Bay
• Whitefish Bay
• Williams Bay

Harbours, cuts and narrows 10

• Bannatyne Narrows
• Chamberlain Narrows
• Ghost Narrows
• Hungry Narrows
• Maclean's Narrows
• Manitou Narrows
• Poplar Narrows
• Shanty Narrows
• Steamboat Narrows
• Windy Narrows

Points on the shore 12

• Bannatyne Point
• Dewey Point
• Lunker Point
• Manitoba Point
• Pine Point
• Quoquat Point
• Rocky Point
• Stone Point
• Stony Point
• Wesley Point
• Willow Point
• Windigo Point

Nearby lakes

• Pelican Lake46 km away
• Abram Lake54 km away
• Wabaskang Lake57 km away
• Minnitaki Lake60 km away

All lakes

Questions about Lac Seul

• How deep is Lac Seul?

  Its deepest charted contour is 36.6 meters, and the water within it is deeper.

• How big is Lac Seul?

  Its surface covers 1,206.5 square kilometers and it holds 1,488 islands. Of its 3,487 kilometers of shoreline, 2,168 kilometers is the mainland shore and 1,319 kilometers is the shore of the islands.