Newboro Lake

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 93 depth contours for Newboro Lake.

See also Ontario's Largest and Deepest Lakes

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 water samples for phosphorus analysis and measure water clarity through the summer with a Secchi disk. Most sites are sampled for phosphorus once a year, in spring, and some several times a year between spring and fall. Phosphorus in many lakes rises through the summer, so the two kinds of average are measured on different bases.

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 average phosphorus:

• Oligotrophic, below 10 micrograms per litre: clear water and low algae.
• Mesotrophic, from 10 to 20: moderately productive water, with more algae and weed growth than an oligotrophic lake but rarely a bloom.
• Eutrophic, above 20: nutrient-rich water, prone to algal blooms and low oxygen at depth.

Newboro Lake has 4 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.

The longest record is held by site 3458/1 at Hungry Bay, with phosphorus sampled once a year over 23 years to 2025. Its long-term mean phosphorus concentration is 12.31 micrograms per litre, within the mesotrophic band, which runs from 10 to 20.

A Secchi disk is a 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.

The 236 clarity readings at site 3458/1 give a median Secchi depth of 4.85 meters.

Median Secchi depth by year at site 3458/1

See also Lake Water Quality and Blue-Green Algae in Ontario

Newboro Lake Weather

The weather page for Newboro Lake carries the forecast over the water, wave heights across the lake, the modelled water temperature, and the water level.

Newboro Lake weather

Water temperature

No provincial monitoring station records water temperature on Newboro Lake. The LastLake model computes the temperature of its surface water for each day from the daily mean air temperature at Environment Canada’s Grenadier Island climate station, 44 kilometers from the lake, or the next nearest station when its record is incomplete, and from the lake’s area of 1,614 hectares and its mean depth of 3.2 meters.

Each day’s figure carries the model’s typical error for that month on lakes of the same size. The figure in the chart below is the temperature near the surface, away from the shoreline. Bays, shallows and water deeper below the surface differ in temperature. Temperature is not measured when ice covers the lake. The weather page for Newboro Lake carries the model’s figures for the past weeks and the coming week.

See also Lake Water Temperature in Ontario

Newboro Lake Water Level

Parks Canada measures the level of Newboro Lake at a gauge on the lake, on the Rideau Canal, and posts one reading each weekday. The record below holds every reading since 1 January 2026, set against Parks Canada’s average, highest and lowest level for each day of the year.

Readings are provisional, posted by Parks Canada on weekdays, and are not intended for flood warning.

Fish in Newboro Lake

Ontario’s aquatic resource records name 24 fish species in Newboro Lake.

Popular 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

Spawning areas

Ontario maps 90 fish spawning records within the Newboro Lake outline, for three different species, and all of them are mapped below.

By number of records

By area mapped

• Largemouth Bass81 areas34.5 ha
• Northern Pike8 areas8.4 ha
• Smallmouth Bass1 area1.8 ha

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.

The province’s record of stocking for recreational fishing, kept from 2016, lists no release into Newboro Lake.

Eating the fish

The 2026 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. Where mercury sets the advice, the figure falls as the fish gets longer, because mercury accumulates over a fish’s life. Where the guide has no result yet for certain contaminants at a location, it sets a precautionary limit of 16 meals a month. 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

Fisheries Management Zone 18

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

Fisheries management zones around Newboro Lake

See also Fishing Seasons in Ontario, Zone by Zone and Fish Stocking in Ontario Lakes

Newboro Lake Ice Fishing

An ice hut on Newboro Lake must be removed by March 15. The province sets dates for ice hut removal as a safety measure to ensure huts are removed before thawing occurs. One date applies to an entire fisheries management zone (FMZ). Newboro Lake lies within FMZ 18.

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 FMZ 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.

See also Lake Ice in Ontario and When the Lakes Will Freeze This Winter

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 mostly inside wetland the province’s Wetland With Significance dataset maps as marsh or open water. The largest two, of 6.0 and 2.6 hectares, fall inside the The Bog Marsh.

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
• Whitefish Lake14 km away
• Big Rideau Lake17 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.