Sudbury District, Ontario
Nepahwin Lake
Seven islands and a deepest charted contour of 22.0 meters, inside the City of Greater Sudbury. Cold water, stocked with splake by the province five times between 2017 and 2021.
- Surface
- 1.3 km²
- Shoreline
- 12 km10 mainland + 2 islands
- Islands
- 7
- Charted depth
- 22.0 m
- Depth contours
- 110
All figures are derived from Ontario’s survey records.
Where Nepahwin Lake is
Nepahwin Lake lies in the District of Sudbury, within the City of Greater Sudbury.
How deep is Nepahwin Lake?
The deepest mapped contour on Nepahwin Lake is 22.0 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 110 depth contours for Nepahwin Lake.
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.
Nepahwin Lake has 10 Lake Partner monitoring sites. Seven have reported phosphorus for the three or more years the province requires before a status is assigned. One of those sites is classified mesotrophic and six eutrophic.
| Site | Location | Years | Last sampled | Classification |
|---|---|---|---|---|
| 6053/7 | Sudbury – deep spot, NEP-1 | 11 | 2025 | eutrophic |
| 6053/4 | Sudbury-S arm | 9 | 2025 | eutrophic |
| 6053/6 | North Arm | 9 | 2025 | eutrophic |
| 6053/10 | Main basin, deep spot | 5 | 2025 | eutrophic |
| 6053/8 | South Arm, deep spot | 5 | 2025 | eutrophic |
| 6053/9 | North Arm, deep spot | 5 | 2025 | eutrophic |
| 6053/3 | Mid Lake, deep spot | 3 | 2006 | mesotrophic |
The longest record is held by site 6053/7 at Sudbury – deep spot, NEP-1, sampled over 11 springs to 2025. Its long-term mean phosphorus concentration is 20.46 micrograms per litre, within the eutrophic band, which begins at 20. The site’s 1 clarity readings give a median Secchi depth of 2.5 meters.
Fish in Nepahwin Lake
Ontario’s aquatic resource records name 13 fish species in Nepahwin Lake. The province classes the lake as cold water. The record took effect on 29 August 2017, and it compiles what field biologists had reported by then. The province’s other records for the lake name three further species, among them walleye and brook trout. They appear in the records below.
Nine of the sixteen species in the province’s records
Lake Trouttrout and whitefish
Rainbow Trouttrout and whitefish
Northern Pikepike
Walleyeperch
Yellow Perchperch
Smallmouth Basssunfish
Rock Basssunfish
Pumpkinseedsunfish
Brown Bullheadcatfish
| Family | Species |
|---|---|
| Trout and whitefish | brook trout, splake |
| Sucker | white sucker |
| Smelt | rainbow smelt |
| Minnow | blacknose shiner, golden shiner |
| Other | lake trout backcross |
Stocking history
Ontario’s stocking records for Nepahwin Lake run from 1983 to 2015 and hold 26 releases. Splake account for most of the fish: 49,140 released in fourteen of the years between 1983 and 2015. The last recorded release was 3,000 splake yearlings in 2015.
| Species | Years | Years with a release | Fish released |
|---|---|---|---|
| Splake | 1983 to 2015 | 14 | 49,140 |
| Lake Trout | 1989 to 1996 | 7 | 16,900 |
| Brook Trout | 2003 to 2005 | 3 | 12,575 |
| Lake Trout Backcross | 1992 to 1992 | 1 | 2,416 |
The province’s current stocking programme, recorded from 2017, lists 14,200 splake released into Nepahwin Lake between 2017 and 2021.
Eating the fish
The 2025 Guide to Eating Ontario Fish carries consumption advice for ten species taken from Nepahwin Lake, tested for contaminants at a sampling location in McKim Twp., Sudbury 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
| Length, cm | 60 to 65 | 65 to 70 | 70 to 75 | over 75 |
|---|---|---|---|---|
| General population | 0 | 0 | 0 | 0 |
| Sensitive population | 0 | 0 | 0 | 0 |
| Length, cm | 70 to 75 | over 75 |
|---|---|---|
| General population | 0 | 0 |
| Sensitive population | 0 | 0 |
| Length, cm | 55 to 60 | 60 to 65 | 65 to 70 | 70 to 75 | over 75 |
|---|---|---|---|---|---|
| General population | 8 | 8 | 8 | 4 | 2 |
| Sensitive population | 8 | 8 | 8 | 4 | 0 |
| 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 | 4 | 2 | 2 | 1 | 0 |
| Sensitive population | 12 | 12 | 4 | 0 | 0 | 0 | 0 |
| Length, cm | 15 to 20 | 20 to 25 | 25 to 30 |
|---|---|---|---|
| General population | 12 | 12 | 12 |
| Sensitive population | 12 | 12 | 12 |
| Length, cm | 15 to 20 |
|---|---|
| General population | 8 |
| Sensitive population | 8 |
| Length, cm | 20 to 25 | 25 to 30 | 30 to 35 | 35 to 40 |
|---|---|---|---|---|
| General population | 8 | 4 | 2 | 1 |
| Sensitive population | 8 | 4 | 0 | 0 |
| Length, cm | 45 to 50 | 50 to 55 |
|---|---|---|
| General population | 1 | 1 |
| Sensitive population | 0 | 0 |
| Length, cm | 15 to 20 |
|---|---|
| General population | 1 |
| Sensitive population | 0 |
| Length, cm | 15 to 20 | 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 | over 75 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| General population | 4 | 4 | 2 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Sensitive population | 4 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Fisheries Management Zone 10
Nepahwin Lake lies in Fisheries Management Zone 10. Ontario sets its fishing seasons and catch limits by zone.
| Species | Open season | Sport licence | Conservation licence |
|---|---|---|---|
| Atlantic Salmon | Jan. 1 – Sept. 30 | 1 | 0 |
| Brook Trout | Jan. 1 – Sept. 30 | 5 | 2 |
| Brown Trout | Open all year | 5 | 2 |
| Channel Catfish | Open all year | 12 | 6 |
| Crappie | Open all year | 30 | 10 |
| Lake Trout | Jan. 1 – Labour Day | 2, not more than 1 greater than 40 cm (15.7 in.) | 1 |
| Lake Whitefish | Open all year | 12 | 6 |
| Largemouth and Smallmouth Bass or any combination | 3rd Saturday in June – November 30 | 6 | 3 |
| Muskellunge | 3rd Sat. in June – Dec. 15 | 1, must be greater than 122 cm (48 in.) | 0 |
| Northern Pike | Open all year | 6; not more than 1 greater than 61 cm, none greater than 86 cm | 2; none greater than 61 cm |
| Pacific Salmon | Open all year | 5 | 2 |
| Rainbow Trout | Open all year | 2 | 1 |
| Splake | Open all year | 5 | 2 |
| Sunfish | Open all year | 50 | 25 |
| Walleye and Sauger or any combination | January 1 to the third Sunday in March and third Saturday in May to December 31 | 4, none greater than 46 cm | 2, none greater than 46 cm |
| 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.
| Species | Open season | Sport licence | Conservation licence |
|---|---|---|---|
| Largemouth and Smallmouth Bass or any combination | Open all year | Zone-wide | Zone-wide |
Where a row reads zone-wide, the zone’s own season or limit above applies.
Nepahwin Lake Ice Fishing
An ice hut on Nepahwin Lake must be removed by March 31. Nepahwin Lake lies in fisheries management zone 10, 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 10 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 Nepahwin Lake on any given day. Ontario publishes ice safety guidance for anyone going out on the ice, at ontario.ca.
Islands and names
Nepahwin Lake contains 7 islands in the Ontario Hydro Network’s outline, zero of them over 10 hectares and three under a tenth of a hectare.
| Island | Hectares | |
|---|---|---|
| 1 | Meda Island | 0.9 |
| 2 | Gordon Island | 0.3 |
| 3 | McMahons Island | 0.2 |
| 4 | unnamed | 0.1 |
| 5 | unnamed | 0.1 |
| 6 | Duck Island | 0.0 |
| 7 | unnamed | 0.0 |
Official names
Ontario’s geographic names register lists 4 official names on the water and its islands: 4 islands.
Nearby lakes
- Ramsey Lake3 km away
- Richard Lake6 km away
- Long Lake14 km away
- Nepewassi Lake28 km away
Questions about Nepahwin Lake
- How deep is Nepahwin Lake?
Its deepest charted contour is 22 meters, and the water within it is deeper.
- How big is Nepahwin Lake?
Its surface covers 1.3 square kilometers and it holds 7 islands. Of its 12 kilometers of shoreline, 10 kilometers is the mainland shore and 2 kilometers is the shore of the islands.
- What fish are in Nepahwin Lake?
Ontario’s aquatic resource records name thirteen species, among them lake trout, smallmouth bass, northern pike and yellow perch. The lake’s spawning, consumption and stocking records also name walleye and brook trout.
A print of Nepahwin Lake
Nepahwin Lake has not yet been drawn as a print. The lakes drawn so far are on the lake maps page, and a print of Nepahwin Lake can be requested by email; whether it can be drawn is confirmed before any payment.
Ask about a Nepahwin Lake printLooking at a property on Nepahwin 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.
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 Nepahwin 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 Nepahwin 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.
- 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; 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.