Rainy River District, Ontario

Marmion Lake

Sixty-two square kilometers of cool water at Atikokan, with 531 islands and 467 kilometers of shoreline, charted to 30.5 meters in the 1972 survey. Three walleye spawning areas are mapped, and the aquatic resource record lists 29 species.

Surface: 62.4 km²
Shoreline: 467 km248 mainland + 219 islands
Islands: 531
Charted depth: 30.5 m
Depth contours: 236

All figures are derived from Ontario’s survey records.

Where Marmion Lake is

Marmion Lake lies in the District of Rainy River, within the Town of Atikokan.

How deep is Marmion Lake?

The deepest mapped contour on Marmion Lake is 30.5 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 236 depth contours for Marmion Lake.

The deepest charted contour on Marmion Lake, 30.5 meters, from the survey of 30 July 1972. The circle marks the centre of that contour, and the water within it is deeper. Two contours reach this depth; the largest is marked. The survey’s 236 depth contours are drawn where the province published them, and along the outline where the survey placed them beyond it. Outline from the Ontario Hydro Network. Each contour is labelled with its depth in meters; zoom in where they run close.

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 a water sample each spring for phosphorus analysis and measure water clarity through the summer with a Secchi disk.

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 spring phosphorus. Below 10 micrograms per litre is oligotrophic: clear water and low algae. From 10 to 20 is mesotrophic: moderately productive water, with more algae and weed growth than an oligotrophic lake but rarely a bloom. Above 20 is eutrophic: nutrient-rich water, prone to algal blooms and low oxygen at depth.

A Secchi disk is a 20 centimeter 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.

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

Fish in Marmion Lake

Ontario’s aquatic resource records name 29 fish species in Marmion Lake. The province classes the lake as cool water. The record took effect on 26 February 2014, and it compiles what field biologists had reported by then.

Eleven of the 29 species in the province’s records

Lake Whitefishtrout and whitefish
Ciscotrout and whitefish
Northern Pikepike
Walleyeperch
Yellow Perchperch
Smallmouth Basssunfish
Black Crappiesunfish
Rock Basssunfish
Pumpkinseedsunfish
Bluegillsunfish
Burbotcod

The other eighteen species in the province’s records
Family	Species
Perch	iowa darter, logperch
Sucker	white sucker
Minnow	blacknose dace, blacknose shiner, emerald shiner, fathead minnow, golden shiner, lake chub, longnose dace, mimic shiner, northern redbelly dace, spottail shiner
Sculpin	deepwater sculpin, slimy sculpin
Stickleback	ninespine stickleback
Mudminnow	central mudminnow
Trout-perch	trout-perch

Spawning areas

Ontario maps 3 fish spawning records within the Marmion Lake outline: 3 walleye spawning areas covering 1.12 hectares.

By number of records

By area mapped

Walleye3 areas1.1 ha

Spawning records mapped by the province within the Marmion Lake outline. A record under 100 square meters is drawn as a dot; a spawning area is drawn as the outline mapped. One colour per species, the same as the bars and the list above.

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 Marmion Lake run from 1998 to 2000 and hold 3 releases. Walleye account for most of the fish: 11,000,000 released in three of the years between 1998 and 2000. The last recorded release was 4,000,000 walleye frys in 2000.

Fish released into Marmion Lake, 1998 to 2000
Species	Years	Years with a release	Fish released
Walleye	1998 to 2000	3	11,000,000

The province’s current stocking programme, recorded from 2016, lists no release into Marmion Lake.

Eating the fish

The 2025 Guide to Eating Ontario Fish carries consumption advice for five species taken from Marmion Lake, tested for contaminants at a sampling location in Rainy River Dist. Each figure below is the most meals a month the guide advises for a fish of that length. The advice 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

Lake Whitefish PCB
Length, cm	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50	50 to 55	55 to 60
General population	2	2	2	2	2	2	2
Sensitive population	0	0	0	0	0	0	0

Walleye Mercury
Length, cm	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50	50 to 55	55 to 60	60 to 65	65 to 70	70 to 75
General population	16	16	16	16	12	8	8	4	4	4
Sensitive population	8	8	8	4	4	4	0	0	0	0

Northern Pike Mercury
Length, cm	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50	50 to 55	55 to 60	60 to 65	65 to 70	70 to 75	over 75
General population	32	32	16	16	16	16	8	8	8	8	4
Sensitive population	16	12	8	8	8	4	4	4	4	4	0

Smallmouth Bass Mercury
Length, cm	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50	50 to 55
General population	16	16	16	8	4	4
Sensitive population	4	4	4	4	0	0

White Sucker no contaminant listed
Length, cm	40 to 45	45 to 50	50 to 55
General population	32	32	32
Sensitive population	16	16	16

Fisheries Management Zone 5

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

Zone 5 seasons and limits, 2026
Species	Open season	Sport licence	Conservation licence
Brook Trout	Open all year	5	2
Brown Trout	Open all year	5	2
Crappie	Open all year	10	5
Lake Trout	Jan. 1 – Sept. 30	2, not more than 1 greater than 56 cm (22 in.) from Sept. 1 – Sept. 30	1, no size limit
Lake Whitefish	Open all year	12	6
Largemouth and Smallmouth Bass or any combination	Open all year	4; Must be less than 35 cm (13.8 in.) from Jan. 1 – June 30	2; Must be less than 35 cm (13.8 in.) from Jan. 1 – June 30
Muskellunge	3rd Sat. in June – Dec. 15	1, must be greater than 102 cm (40 in.)	0
Northern Pike	Open all year	4; none greater than 75 cm (29.5 in.)	2; none greater than 75 cm (29.5 in.)
Rainbow Trout	Open all year	5	2
Splake	Open all year	5	2
Sunfish	Open all year	50	25
Walleye and Sauger or any combination	Jan. 1 – Apr. 14 & 3rd Sat. in May – Dec. 31	4, not more than 1 greater than 46 cm (18.1 in.)	2, not more than 1 greater than 46 cm (18.1 in.)
Yellow Perch	Open all year	50	25

The figures are the number of fish an angler may catch and keep in a day and have in possession, under a sport fishing licence and under a conservation licence. The rows are the whole zone’s, and they apply to every lake in it. No waterbody exception names Marmion Lake. Zone-wide, Smelt may not be used as bait or possessed for use as bait.

Islands and names

Marmion Lake contains 531 islands in the Ontario Hydro Network’s outline, sixteen of them over 10 hectares and 265 under a tenth of a hectare.

The ten largest islands, numbered to the table. Areas are measured on the province’s outline.

The ten largest islands
	Island	Hectares
1	unnamed	243.8
2	unnamed	153.5
3	unnamed	58.1
4	unnamed	56.5
5	unnamed	55.2
6	unnamed	38.1
7	unnamed	27.4
8	unnamed	23.2
9	unnamed	22.4
10	unnamed	22.1

Official names

Ontario’s geographic names register lists 5 official names on the water and its islands: 1 island, three bays and one narrows. A further 2 named points stand on the mainland shore.

Bays 3

Lower Seine Bay
Lynxhead Bay
Sawbill Bay

Harbours, cuts and narrows 1

Lynxhead Narrows

Points on the shore 2

Fallenrock Point
Gamik Point

Nearby lakes

All lakes

Questions about Marmion Lake

How deep is Marmion Lake?
Its deepest charted contour is 30.5 meters, and the water within it is deeper.
How big is Marmion Lake?
Its surface covers 62.4 square kilometers and it holds 531 islands. Of its 467 kilometers of shoreline, 248 kilometers is the mainland shore and 219 kilometers is the shore of the islands.
What fish are in Marmion Lake?
Ontario’s aquatic resource records name 29 species, among them walleye, smallmouth bass, northern pike, lake whitefish, yellow perch and black crappie.

A print of Marmion Lake

Marmion Lake has not yet been drawn as a print. The lakes drawn so far are on the lake maps page, and a print of Marmion Lake can be requested by email; whether it can be drawn is confirmed before any payment.

Ask about a Marmion Lake print

Looking at a property on Marmion Lake?

Depth and water quality are two records out of many. Our Rural & Cottage Buyer’s Report gathers what the public record holds about one specific address: shore road allowance, road access, wells, flood mapping, Crown land, wetlands and more, read and checked by a person before it is sent.

See what is in the report

What these figures do and do not say

Depth: A depth reading is the distance from the water surface on the day of survey to the lake bottom. Lake levels vary through the season and between years. The depth figure above is the deepest contour charted and is a minimum; the depth within it was not recorded. The figures for Marmion Lake are read from the province’s bathymetry records within the Ontario Hydro Network’s outline of the lake: the deepest figure is the deepest record inside that outline, and the count is every record inside it.
Shoreline and surface: The shoreline figure is the length of the mainland shore and of every island shore added together, measured on the Ontario Hydro Network’s outline of the lake. The surface figure is the area of water inside that outline, less the area of its islands. The provincial outline is mapped to within a few meters of the shore, and a shoreline measured from a coarser map comes out shorter, which is why a figure published elsewhere is often lower.
Survey coverage: Not every survey covered every arm of a lake, and the province’s index does not always record where a survey ended.
Nearby lakes: Distances are measured between lake centres.
Islands and names: Islands are counted and measured on the Ontario Hydro Network outline; names are the register’s, placed by its own coordinate. The register names islands the outline draws as part of a larger one, and the outline holds islands the register has not named, so the two counts differ. The outline carries some lakes across marsh, so a gap in the marsh is drawn as land, and every such gap is included in the island count. Where the register has not named one and it lies mostly inside a wetland in the province’s Wetland With Significance dataset, the page names the wetland and the table of largest islands leaves it out. Wetland boundaries are mapped at their own scale and can cover a small island whole.
Depth contours: Each contour is drawn where the survey placed it, at the survey’s own positional accuracy. The survey carries its own shoreline, which differs from the Ontario Hydro Network’s outline, so a contour near the shore can run to or past the outline. Such a stretch is drawn along the outline, as a drawing convention, and is not the survey’s line there. The contour count in the stat band is the province’s, and it includes the survey’s own shoreline contour, one ring around the mainland and one around each charted island, which the map leaves off; the map’s small print gives the split.
Location: Municipal boundaries are read from the province’s records as published and can lag a boundary change.
Fish: Ontario’s fish records are compilations of existing knowledge from field biologists and do not represent exhaustive inventories. A species that is not listed was not ruled out. The species list carries one date for the whole record and none for any species.
Spawning areas: A spawning area is drawn where the province mapped it, at the province’s stated accuracy, and the record says nothing about how many fish use it in a given year. A nest record is one nest seen on one day; a count of nests is not a count of fish, and a count of records is not a comparison between species. Whether a given piece of work needs an authorization is a determination made by Fisheries and Oceans Canada on the work itself.
Stocking: A stocking record is a release on a date. It says nothing about how many fish survived or about the population in the lake today.
Eating advice: The guide’s advice is for fish taken from the lake at the tested location and applies to the size classes tested. The province’s guide is the authority and is updated each year.
Fishing rules: Seasons and limits are the zone’s, for the year of the dataset the page was built from, and a licence’s own conditions and any waterbody exception apply over them. The province’s regulations summary is the authority.

Where these figures come from

Depth, shoreline, islands and named places: Ontario Ministry of Natural Resources bathymetry and the Ontario Hydro Network, © King’s Printer for Ontario, Open Government Licence – Ontario.
Aerial photography: Ontario Imagery Web Map Service, Open Government Licence – Ontario, drawing this frame from North Western Ontario Orthophotography Project 2022, Northwestern Ontario Orthophotography Project 2017, Forest Resources Inventory 2007-2011 and Sentinel 2 2025, satellite.
Official names: Geographic Names Ontario, Ministry of Natural Resources, Open Government Licence – Ontario. Marinas: Overture Maps Foundation places data, CDLA-Permissive 2.0.
Lake outline and municipal boundaries: Ontario Hydro Network and Ontario municipal boundary records, Ministry of Natural Resources, Open Government Licence – Ontario.
Fish species and thermal regime: Ontario Aquatic Resource Area records. Spawning areas: Ontario Fish Activity Area records. Both Ministry of Natural Resources, Open Government Licence – Ontario.
Stocking: Historical Fish Stocking Data and Fish Stocking Data for Recreational Purposes, Ministry of Natural Resources, Open Government Licence – Ontario.
Consumption advice: Guide to Eating Ontario Fish advisory database, 2025 edition, Ministry of the Environment, Conservation and Parks, Open Government Licence – Ontario.
Seasons and limits: Ontario recreational fishing regulations data, Ministry of Natural Resources, Open Government Licence – Ontario.
Fish plates: Duane Raver, U.S. Fish and Wildlife Service; Ellen Edmonson and Hugh Chrisp, New York State Conservation Department; Timothy Knepp, U.S. Fish and Wildlife Service; U.S. Fish and Wildlife Service. All public domain.