Hastings County, Ontario

Lake St. Peter

A deepest charted contour of 27.4 meters, from the province's 1959 survey, in the Municipality of Hastings Highlands. Cold water, with seven lake trout spawning shoals and three smallmouth bass spawning areas recorded.

Surface: 2.4 km²
Shoreline: 16 km
Islands: 1
Charted depth: 27.4 m
Depth contours: 29

All figures are derived from Ontario’s survey records.

Where Lake St. Peter is

Lake St. Peter lies in the County of Hastings, within the Municipality of Hastings Highlands.

How deep is Lake St. Peter?

The deepest mapped contour on Lake St. Peter is 27.4 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 29 depth contours for Lake St. Peter.

The deepest charted contour on Lake St. Peter, 27.4 meters, from the 1959 survey. The circle marks the centre of that contour, and the water within it is deeper. Of the survey’s 29 contours, two are its own shoreline contour, one ring around the mainland and one around each island it charted, and are left off, the outline being the Ontario Hydro Network’s; the other 27 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.

Lake St. Peter has 3 Lake Partner monitoring sites. One of them has reported phosphorus for the three or more years the province requires before a status is assigned, and is classified oligotrophic.

Lake Partner sites on Lake St. Peter with a quotable phosphorus record
Site	Location	Years	Last sampled	Classification
5147/1	Mid Lake, deep spot	10	2025	oligotrophic

The longest record is held by site 5147/1 at Mid Lake, deep spot, sampled over 10 springs to 2025. Its long-term mean phosphorus concentration is 7.29 micrograms per litre, within the oligotrophic band, which extends to 10. The site’s 59 clarity readings give a median Secchi depth of 2.8 meters.

Median Secchi depth by year at site 5147/1, surface at the top. The thin line through each bar spans the shallowest and deepest reading that year, and the row beneath the years gives the number of readings. Years without readings are blank.

Water temperature

Ontario’s aquatic resource records class Lake St. Peter as a cold-water lake.

A lake separates into layers through the summer where it is deep enough. Sunlight and wind warm and mix the upper few meters, and beneath a band of rapid cooling, the thermocline, the water stays cold. A shallow lake mixes to the bottom instead and warms through, sooner in spring and later into autumn.

No provincial monitoring station records water temperature on Lake St. Peter. The province’s longest in-water record is kept on eight research lakes near Dorset, sampled since 1976. A reading is taken at the surface, at one meter, at each meter to seven and then every two meters to the bottom, about every two weeks through the open-water season and about monthly under ice. The record holds 5,240 readings at a depth of one meter.

At one meter the eight lakes track one another closely. On a day when several were sampled, the warmest and the coolest lake differed by about one degree in every month of the year, and a 12 meter deep lake and a 37 meter deep lake read within 0.2 degrees of each other from June to October. The weather of the year, and not the lake, sets most of the width of the band below.

Water temperature at a depth of one meter, by half-month, on eight research lakes near Dorset, 1976 to 2025. The band holds the middle 80% of the 5,240 readings taken at one meter; the line is the median. The warmest tenth of years lie above the band and the coolest tenth below it.

Satellite thermal imagery gives a surface reading on clear days: the Landsat sensors pass over Lake St. Peter every eight days at a resolution of 100 meters. In the province’s record the surface reading and the one meter reading agree to within half a degree nine times in ten in summer.

The water a few meters down is colder than any figure on this chart, in every month of the year.

How depth changes the temperature

The chart below is the province’s record on Harp Lake, 37 meters deep, drawn as the median temperature at each depth for each month over 49 years. In July the water at one meter is 23 degrees, at five meters 15, at seven meters 9, and from 13 meters to the bottom under 6. By October the warm layer has deepened to seven meters and cooled to 11 degrees. In February the whole column sits between 1 and 4 degrees under the ice, coldest at the top.

February, under ice
May
June
July
August
September
October

Temperature against depth on Harp Lake, near Dorset, as the median of every reading at that depth in that month, 1976 to 2025. Surface at the top. The thermocline is the bend in each line.

A shallower lake in the same record warms sooner. Heney Lake, six meters deep, reads about 1.8 degrees warmer than Harp Lake at one meter from January to May, 0.8 degrees warmer from June to August, and the same or cooler from September.

Fish in Lake St. Peter

Ontario’s aquatic resource records name 10 fish species in Lake St. Peter. The province classes the lake as cold water. The record took effect on 1 May 2017, and it compiles what field biologists had reported by then. The province’s other records for the lake name one further species, rainbow trout. It appears in the records below.

Seven of the eleven species in the province’s records

Lake Trouttrout and whitefish
Brook Trouttrout and whitefish
Yellow Perchperch
Smallmouth Basssunfish
Largemouth Basssunfish
Rock Basssunfish
Pumpkinseedsunfish

The other four species in the province’s records
Family	Species
Trout and whitefish	rainbow trout
Sucker	white sucker
Minnow	common shiner, creek chub

Spawning areas

Ontario maps 10 fish spawning records within the Lake St. Peter outline, for two species, all of them mapped areas.

By number of records

By area mapped

Lake Trout7 areas0.5 ha
Smallmouth Bass3 areas0.2 ha

Spawning records mapped by the province within the Lake St. Peter 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 Lake St. Peter run from 1946 to 2014 and hold 80 releases. Lake Trout account for most of the fish: 101,690 released in 40 of the years between 1946 and 2014. The last recorded release was 1,105 lake trout yearlings in 2014.

Fish released into Lake St. Peter, 1946 to 2014
Species	Years	Years with a release	Fish released
Lake Trout	1946 to 2014	40	101,690
Rainbow Trout	1961 to 1984	19	78,299
Brook Trout	1946 to 1963	14	39,500

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

Eating the fish

The 2025 Guide to Eating Ontario Fish carries consumption advice for one species taken from Lake St. Peter, tested for contaminants at a sampling location in McClure Twp., Hastings Co. 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, PCB
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	over 75
General population	32	16	16	16	16	16	12	8	8	8	4	2
Sensitive population	16	12	8	8	8	4	4	4	4	0	0	0

Fisheries Management Zone 15

Lake St. Peter lies in Fisheries Management Zone 15. Ontario sets its fishing seasons and catch limits by zone. Zone 15 covers central Ontario from Georgian Bay to the Ottawa River, bounded to the north by the Pickerel River, Highway 522 and the northern edge of Algonquin Park. It takes in Parry Sound, Huntsville, Bracebridge, Bancroft, Pembroke and Renfrew, and the whole of Algonquin Provincial Park. The province describes it as a zone of many natural lake trout and brook trout lakes, with a well-developed road network and moderate angling effort.

Zone 15 seasons and limits, 2026
Species	Open season	Sport licence	Conservation licence
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 – Sept. 30	2	1
Lake Whitefish	Open all year	12	6
Largemouth and Smallmouth Bass or any combination	4th Sat. in June – Nov. 30	6	2
Muskellunge	1st Sat. in June – Dec. 15	1, must be greater than 91 cm (36 in.)	0
Northern Pike	Jan. 1 – Mar. 31 & 3rd Sat. in May – Dec. 31	6	2
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 – Mar. 15 & 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.

Exceptions for Lake St. Peter itself, 2026
Species	Open season	Sport licence	Conservation licence	Size limit
Lake Trout	Zone-wide	Zone-wide	Zone-wide	None between 33 – 40 cm (13 – 15.7 in.)

Where a row reads zone-wide, the zone’s own season or limit above applies. Lake Trout: Only one line may be used when angling through the ice.

Lake St. Peter Ice Fishing

An ice hut on Lake St. Peter must be removed by March 31. Lake St. Peter lies in fisheries management zone 15, 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 15 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.

When the ice comes and goes

No ice record is kept on Lake St. Peter. The province’s nearest long record covers eight lakes near Dorset, about 72 kilometers away. It holds a date for every winter since 1975, observed by eye and from cameras set on the shore.

On those eight lakes the median date of complete ice cover is December 7 and the median date of complete ice loss is April 20, a median season of 134 days.

The date the ice forms has moved later through the record: a November 26 average across 1971 to 1980, and December 11 across 2011 to 2020. The date it leaves has moved by less than a day each decade over the same period. The two charts below are drawn to one scale of 26 days, so they can be read against each other.

Mean date of complete ice cover on eight lakes near Dorset, by decade, with the number of recorded winters beneath. Ontario Ministry of the Environment, Conservation and Parks, Dorset Environmental Science Centre.

Mean date of complete ice loss on the same eight lakes, by decade, drawn to the same scale of days as the chart above. Ontario Ministry of the Environment, Conservation and Parks, Dorset Environmental Science Centre.

Ice conditions

No public record reports the thickness or the condition of the ice on Lake St. Peter on any given day. Ontario publishes ice safety guidance for anyone going out on the ice, at ontario.ca.

Islands and names

Lake St. Peter contains one island in the Ontario Hydro Network’s outline, of 0.3 hectare.

Official names

Ontario’s geographic names register lists 3 official names on the water and its islands: 1 island. The register records the origin of one name: Summer Island, “The owners of the island spend their summers there.”

Nearby lakes

Bark Lake20 km away
Baptiste Lake21 km away
Kamaniskeg Lake29 km away
Percy Lake29 km away

All lakes

Questions about Lake St. Peter

How deep is Lake St. Peter?
Its deepest charted contour is 27.4 meters, and the water within it is deeper.
How big is Lake St. Peter?
Its surface covers 2.4 square kilometers, with 16 kilometers of shoreline and 1 islands.
What fish are in Lake St. Peter?
Ontario’s aquatic resource records name ten species, among them lake trout, smallmouth bass, largemouth bass, yellow perch and brook trout. The lake’s spawning, consumption and stocking records also name rainbow trout.
Is the water clear?
The one monitoring site with a phosphorus status is classified oligotrophic, the clearest of the province’s three bands.

A print of Lake St. Peter

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

Ask about a Lake St. Peter print

Looking at a property on Lake St. Peter?

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 Lake St. Peter 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 Lake St. Peter 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.
Temperature: The temperature band is the province’s record on eight research lakes near Dorset and is a range for the half-month. It is never a reading from Lake St. Peter, and a larger and deeper lake can warm later in spring and cool later in autumn than the lakes in the record. A satellite reading measures the surface on the day of the pass. Water below the surface layer is colder than any figure on this page, and cold-water shock can occur in water below about 15 degrees.
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 dates: A break-up date is the day a lake was recorded as no longer completely covered by ice, and a freeze date is the day it was recorded as completely covered. Both are read from the shore. A winter carrying no date is a winter nobody recorded, and not a winter without ice. Each Dorset figure is the average of the eight lakes and is not a record of Lake St. Peter. All eight lie within 10 to 30 kilometers of Dorset. They are smaller and shallower than most of the lakes on these pages, and a smaller lake freezes sooner.
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.
Water temperature: Inland Lakes and Streams, Physical Conditions, Dorset Environmental Science Centre, Ministry of the Environment, Conservation and Parks, Open Government Licence – Ontario, 1976 to 2025. Surface temperature: Landsat 8 and 9, U.S. Geological Survey, public domain.
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; U.S. Fish and Wildlife Service. All public domain.
Ice dates near Dorset: Inland Lakes and Streams, Physical Conditions, Dorset Environmental Science Centre, Ministry of the Environment, Conservation and Parks, Open Government Licence – Ontario, 1974 to 2022.
Ice hut removal dates and registration: Ontario fishing regulations, read September 2026.