Leeds and Grenville, Ontario

Newboro Lake

One hundred and eighty-five islands along 126 kilometers of shoreline in the Township of Rideau Lakes, charted to 22.9 meters in the province's 1968 survey. Eighty-one largemouth bass spawning areas are recorded.

Surface: 16.1 km²
Shoreline: 126 km59 mainland + 67 islands
Islands: 185
Charted depth: 22.9 m
Depth contours: 223

All figures are derived from Ontario’s survey records.

Where Newboro Lake is

Newboro Lake lies in the United Counties of Leeds and Grenville, within the Township of Rideau Lakes.

How deep is Newboro Lake?

The deepest mapped contour on Newboro Lake is 22.9 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 223 depth contours for Newboro Lake.

The deepest charted contour on Newboro Lake, 22.9 meters, from the survey of 7 April 1968. The circle marks the centre of that contour, and the water within it is deeper. Two contours reach this depth; the largest is marked. Of the survey’s 223 contours, 130 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 93 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.

Newboro Lake has 3 Lake Partner monitoring sites. Two have reported phosphorus for the three or more years the province requires before a status is assigned. All are classified mesotrophic.

Lake Partner sites on Newboro Lake with a quotable phosphorus record
Site	Location	Years	Last sampled	Classification
3458/1	Hungry Bay	23	2025	mesotrophic
3458/3	Mid Bay, Deep Spot	8	2025	mesotrophic

The longest record is held by site 3458/1 at Hungry Bay, sampled over 23 springs to 2025. Its long-term mean phosphorus concentration is 12.31 micrograms per litre, within the mesotrophic band, which runs from 10 to 20. The site’s 236 clarity readings give a median Secchi depth of 4.85 meters.

Median Secchi depth by year at site 3458/1, 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.

Fish in Newboro Lake

Ontario’s aquatic resource records name 24 fish species in Newboro Lake. The record took effect on 24 June 2020, and it compiles what field biologists had reported by then.

Eleven of the 24 species in the province’s records

Northern Pikepike
Walleyeperch
Yellow Perchperch
Smallmouth Basssunfish
Largemouth Basssunfish
Black Crappiesunfish
Rock Basssunfish
Pumpkinseedsunfish
Bluegillsunfish
Brown Bullheadcatfish
Common Carpminnow

The other thirteen species in the province’s records
Family	Species
Catfish	yellow bullhead
Sucker	suckers
Smelt	rainbow smelt
Minnow	blackchin shiner, blacknose shiner, common shiner, golden shiner, lake chub, spotfin shiner, spottail shiner
Herring	alewife
Eel	american eel
Mudminnow	central mudminnow

Spawning areas

Ontario maps 90 fish spawning records within the Newboro Lake outline, for three species, all of them mapped areas. Three of the areas are one outline mapped for largemouth bass and northern pike alike. An outline filed for more than one species is drawn once, striped in each of their colours.

By number of records

By area mapped

Largemouth Bass81 areas210.1 ha
Northern Pike8 areas20.2 ha
Smallmouth Bass1 area1.8 ha

Spawning records mapped by the province within the Newboro 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. An outline filed for more than one species is striped in each of their colours; zoom in to read the stripes.

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 Newboro Lake run from 1948 to 1978 and hold 38 releases. Largemouth Bass account for most of the fish: 68,116 released in fourteen of the years between 1948 and 1968. The last recorded release was 2,000 smallmouth bass frys in 1978.

Fish released into Newboro Lake, 1948 to 1978
Species	Years	Years with a release	Fish released
Largemouth Bass	1948 to 1968	14	68,116
Smallmouth Bass	1949 to 1978	18	40,600

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

Eating the fish

The 2025 Guide to Eating Ontario Fish carries consumption advice for nine species taken from Newboro Lake, tested for contaminants at a sampling location in N. & S. Crosby Twps., Leeds 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

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

Smallmouth Bass Mercury, PCB
Length, cm	20 to 25	25 to 30	30 to 35	35 to 40	40 to 45
General population	16	12	8	4	4
Sensitive population	4	4	0	0	0

Largemouth Bass Mercury
Length, cm	20 to 25	25 to 30	30 to 35	35 to 40	40 to 45	45 to 50
General population	16	16	8	8	4	4
Sensitive population	8	4	4	0	0	0

Yellow Perch Mercury
Length, cm	15 to 20	20 to 25	25 to 30
General population	32	16	12
Sensitive population	12	8	4

Black Crappie Mercury
Length, cm	15 to 20	20 to 25
General population	16	4
Sensitive population	4	0

Rock Bass Mercury
Length, cm	20 to 25	25 to 30
General population	16	12
Sensitive population	8	4

Pumpkinseed no contaminant listed
Length, cm	15 to 20	20 to 25
General population	32	32
Sensitive population	12	12

Brown Bullhead no contaminant listed
Length, cm	20 to 25	25 to 30
General population	32	32
Sensitive population	32	32

Bluegill Mercury
Length, cm	15 to 20	20 to 25
General population	16	16
Sensitive population	8	8

Fisheries Management Zone 18

Newboro Lake lies in Fisheries Management Zone 18. Ontario sets its fishing seasons and catch limits by zone.

Zone 18 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
Channel Catfish	Open all year	12	6
Crappie	Open all year	30	10
Lake Trout	4th Sat. in May – Sept. 8	2	1
Lake Whitefish	Open all year	12	6
Largemouth and Smallmouth Bass or any combination	3rd Sat. in June – Dec. 15	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 & 2nd 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	300, only 30 may be greater than 18 cm (7.1 in.)	15
Walleye and Sauger or any combination	Jan. 1 – Mar. 1 & 2nd Sat. in May – Dec. 31	4, must be between 40 – 50 cm (15.7 – 19.7 in.)	2, must be between 40 – 50 cm (15.7 – 19.7 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 Newboro Lake.

Fish sanctuaries recorded for Newboro Lake
Where	Closed
Newboro Lake (Old Iron Mine Bay) – North Crosby and South Crosby Twps	Closed all year
Newboro Lake (The Bog) – South Crosby Twp	Closed all year

Newboro Lake Ice Fishing

An ice hut on Newboro Lake must be removed by March 15. Newboro Lake lies in fisheries management zone 18, 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 18 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 Newboro Lake on any given day. Ontario publishes ice safety guidance for anyone going out on the ice, at ontario.ca.

Islands and names

Newboro Lake contains 185 islands in the Ontario Hydro Network’s outline, four of them over 10 hectares and 88 under a tenth of a hectare. Thirty-three of them lie inside wetlands mapped in the province’s Wetland With Significance dataset. The largest two, of 6.0 and 2.6 hectares, fall inside the The Bog Marsh.

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

The ten largest islands outside a mapped wetland
	Island	Hectares
1	Rosal Island	19.2
2	Stedmans Island	18.0
3	Foley Island	11.2
4	McCaskill Island	10.1
5	Pritchards Island	7.7
6	Pine Island	7.2
7	Wright Island	7.0
8	Bobs Island	6.5
9	Emerald Island	5.9
10	Long Island	5.8

Official names

Ontario’s geographic names register lists 71 official names on the water and its islands: 52 islands, nine bays, four rocks, one narrows and one point on an island. A further 9 named points stand on the mainland shore.

Bays 9

Bass Bay
Hungry Bay
Iron Mine Bay
Lewis Bay
Lucky Bay
Millers Bay
Rosal Bay
Stouts Lower Bay
Stouts Upper Bay

Shoals and rocks 4

Caviar Rock
March Rock
Sanctuary Rock
Shadow Rock

Harbours, cuts and narrows 1

Stevens Creek

Points on the shore 9

Benson Point
Brady Point
Edwards Point
Gibsons Point
Grass Point
Hungry Bay Point
McNallys Point
Mosquito Point
Tetts Point

Nearby lakes

Sand Lake8 km away
Devil Lake12 km away
Big Rideau Lake13 km away
Upper Beverley Lake19 km away

All lakes

Questions about Newboro Lake

How deep is Newboro Lake?
Its deepest charted contour is 22.9 meters, and the water within it is deeper.
How big is Newboro Lake?
Its surface covers 16.1 square kilometers and it holds 185 islands. Of its 126 kilometers of shoreline, 59 kilometers is the mainland shore and 67 kilometers is the shore of the islands.
What fish are in Newboro Lake?
Ontario’s aquatic resource records name 24 species, among them walleye, smallmouth bass, largemouth bass, northern pike, yellow perch and black crappie.
Is the water clear?
All two monitoring sites with a phosphorus status are classified mesotrophic, the middle of the province’s three bands.

A print of Newboro Lake

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

Ask about a Newboro Lake print

Looking at a property on Newboro 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 Newboro 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 Newboro 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; 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.