Nipissing District, Ontario

Cassels Lake

Seven square kilometers of cold water at Temagami, with 14 islands and 51 kilometers of shoreline, charted to 30.5 meters in the 1971 survey. Two walleye spawning areas are mapped, and the aquatic resource record lists 25 species.

Surface: 7.4 km²
Shoreline: 51 km48 mainland + 3 islands
Islands: 14
Charted depth: 30.5 m
Depth contours: 25

All figures are derived from Ontario’s survey records.

Where Cassels Lake is

Cassels Lake lies in the District of Nipissing, within the Municipality of Temagami.

How deep is Cassels Lake?

The deepest mapped contour on Cassels Lake is 30.5 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 25 depth contours for Cassels Lake.

The deepest charted contour on Cassels Lake, 30.5 meters, from the survey of 16 August 1971. The circle marks the centre of that contour, and the water within it is deeper. The survey’s twenty-five 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.

Cassels Lake has 10 Lake Partner monitoring sites. Three have reported phosphorus for the three or more years the province requires before a status is assigned. All are classified oligotrophic.

Lake Partner sites on Cassels Lake with a quotable phosphorus record
Site	Location	Years	Last sampled	Classification
774/1	1 N Centre, deep spot	5	2013	oligotrophic
774/4	Mid Lake, deep spot	5	2007	oligotrophic
774/6	6 S	4	2013	oligotrophic

The longest record is held by site 774/1 at 1 N Centre, deep spot, sampled over 5 springs to 2013. Its long-term mean phosphorus concentration is 5.32 micrograms per litre, within the oligotrophic band, which extends to 10. The site’s 2 clarity readings give a median Secchi depth of 3.4 meters.

Fish in Cassels Lake

Ontario’s aquatic resource records name 25 fish species in Cassels Lake. The province classes the lake as cold water. The record took effect on 22 February 2017, and it compiles what field biologists had reported by then.

Eleven of the 25 species in the province’s records

Lake Trouttrout and whitefish
Lake Whitefishtrout and whitefish
Ciscotrout and whitefish
Northern Pikepike
Walleyeperch
Yellow Perchperch
Smallmouth Basssunfish
Rock Basssunfish
Pumpkinseedsunfish
Burbotcod
Brown Bullheadcatfish

The other fourteen species in the province’s records
Family	Species
Perch	iowa darter, logperch
Sucker	longnose sucker, white sucker
Minnow	bluntnose minnow, common shiner, creek chub, emerald shiner, mimic shiner, spottail shiner
Sculpin	spoonhead sculpin
Mudminnow	central mudminnow
Trout-perch	trout-perch
Other	whitefish subfamily

Spawning areas

Ontario maps 2 fish spawning records within the Cassels Lake outline: 2 walleye spawning areas covering 5.47 hectares.

By number of records

By area mapped

Walleye2 areas5.5 ha

Spawning records mapped by the province within the Cassels 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 Cassels Lake run from 1947 to 2006 and hold 38 releases. Walleye account for most of the fish: 966,915 released in seven of the years between 1947 and 2006. The last recorded release was 8,975 walleye frys in 2006.

Fish released into Cassels Lake, 1947 to 2006
Species	Years	Years with a release	Fish released
Walleye	1947 to 2006	7	966,915
Lake Trout	1947 to 1990	25	64,873
Smallmouth Bass	1948 to 1950	2	900

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

Eating the fish

The 2025 Guide to Eating Ontario Fish carries consumption advice for seven species taken from Cassels Lake, tested for contaminants at a sampling location in Cassels & Riddell Twps., Nipissing 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 Trout Mercury
Length, cm	20 to 25	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	12	12	8	8	8	4	4	4	4	2	2
Sensitive population	4	4	4	4	0	0	0	0	0	0	0

Lake Whitefish Mercury
Length, cm	20 to 25	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50	50 to 55
General population	12	12	12	12	12	12	12
Sensitive population	4	4	4	4	4	4	4

Walleye Mercury
Length, cm	20 to 25	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	12	8	8	4	4	4	4	4	2	2	0
Sensitive population	4	4	0	0	0	0	0	0	0	0	0

Northern Pike Mercury
Length, cm	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	12	12	8	8	4	4	4	4
Sensitive population	4	4	4	0	0	0	0	0

Smallmouth Bass Mercury
Length, cm	15 to 20	20 to 25	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50
General population	12	12	8	8	4	4	2
Sensitive population	4	4	4	4	0	0	0

Burbot Mercury
Length, cm	25 to 30	30 to 35	35 to 40	40 to 45
General population	16	12	8	4
Sensitive population	8	4	0	0

White Sucker Mercury
Length, cm	35 to 40	40 to 45	45 to 50	50 to 55
General population	32	32	16	16
Sensitive population	16	12	8	8

Fisheries Management Zone 11

Cassels Lake lies in Fisheries Management Zone 11. Ontario sets its fishing seasons and catch limits by zone.

Zone 11 seasons and limits, 2026
Species	Open season	Sport licence	Conservation licence
Brook Trout	Feb. 15 – Sept. 30	5, not more than 1 greater than 31 cm (12.2 in.)	2, none greater than 31 cm (12.2 in.)
Brown Trout	4th Sat. in Apr. – Sept. 30	5	2
Channel Catfish	Open all year	12	6
Crappie	Open all year	30	10
Lake Trout	February 15 to third Sunday in March and third Saturday in May to Labour Day	2; not more than 1 greater than 40 cm	1
Lake Whitefish	Open all year	12	6
Largemouth and Smallmouth Bass or any combination	January 1 to third Sunday in March and third Saturday in May to December 31	6	2
Muskellunge	3rd Sat. in June – Dec. 15	1, must be greater than 122 cm (48 in.)	0
Northern Pike	Jan. 1 – 3rd Sun. in Mar. & 3rd Sat. in May – Dec. 31	6, not more than 2 greater than 61 cm (24 in.), of which not more than 1 is greater than 86 cm (33.9 in.)	2, not more than 1 greater than 61 cm (24 in.), none greater than 86 cm (33.9 in.)
Pacific Salmon	Open all year	5	2
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 – 3rd Sun. in Mar. & 3rd Sat. in May – Dec. 31	4, none between 43 – 60 cm (16.9 – 23.6 in.), not more than 1 greater than 60 cm (23.6 in.)	2, none between 43 – 60 cm (16.9 – 23.6 in.), not more than 1 greater than 60 cm (23.6 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 Cassels Lake.

Fish sanctuaries recorded for Cassels Lake
Where	Closed
Net Creek – Cassels Twp., from dam on Net Lake to 200 m (656 ft.) in an arc extending out into Cassels Lake	No fishing from Apr. 1 – June 15

Cassels Lake Ice Fishing

An ice hut on Cassels Lake must be removed by March 31. Cassels Lake lies in fisheries management zone 11, one of the twenty zones Ontario sets its fishing rules by, and one removal date applies across the whole zone.

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 zone 11 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 Cassels Lake on any given day. Ontario publishes ice safety guidance for anyone going out on the ice, at ontario.ca.

Islands and names

Cassels Lake contains 14 islands in the Ontario Hydro Network’s outline, zero of them over 10 hectares and nine 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	7.9
2	unnamed	1.6
3	unnamed	1.1
4	unnamed	0.3
5	unnamed	0.1
6	unnamed	0.0
7	unnamed	0.0
8	unnamed	0.0
9	unnamed	0.0
10	unnamed	0.0

Nearby lakes

Net Lake6 km away
Rabbit Lake11 km away
Lake Temagami24 km away
Red Cedar Lake44 km away

All lakes

Questions about Cassels Lake

How deep is Cassels Lake?
Its deepest charted contour is 30.5 meters, and the water within it is deeper.
How big is Cassels Lake?
Its surface covers 7.4 square kilometers and it holds 14 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 Cassels Lake?
Ontario’s aquatic resource records name 25 species, among them lake trout, walleye, smallmouth bass, northern pike, lake whitefish and yellow perch.
Is the water clear?
All three monitoring sites with a phosphorus status are classified oligotrophic, the clearest of the province’s three bands.

A print of Cassels Lake

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

Ask about a Cassels Lake print

Looking at a property on Cassels 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 Cassels 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.
Water quality: Each figure belongs to a single monitoring site and not to the lake as a whole. A bay receiving a creek can read differently from open water half a kilometer away. Sites are matched to Cassels Lake by name in the province’s records.
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.
Ice hut rules: Removal dates and registration rules are set by fisheries management zone and change from time to time. The dates here were read from the province in September 2026. The province’s own fishing regulations are 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.
Phosphorus and water clarity: Ontario Lake Partner Program, Ministry of the Environment, Conservation and Parks, Open Government Licence – Ontario. Extract built 2026-08-09.
Aerial photography: Geospatial Ontario imagery, Open Government Licence – Ontario, released collections only.
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.
Ice hut removal dates and registration: Ontario fishing regulations, read September 2026.