Bobs Lake

Where Bobs Lake is

Bobs Lake lies in the County of Lanark and the County of Frontenac, with shoreline in the Township of South Frontenac, the Township of Tay Valley and the Township of Central Frontenac.

How deep is Bobs Lake?

The deepest mapped contour on Bobs Lake is 24.4 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 122 depth contours recorded in Ontario’s transect survey for Bobs 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.

Bobs Lake has 24 Lake Partner monitoring sites. Nineteen have reported phosphorus for the three or more years the province requires before a status is assigned. Thirteen of those sites are classified oligotrophic and six mesotrophic.

The longest record is held by site 510/10 at Norris Bay, with phosphorus sampled once a year over 24 years to 2025. Its long-term mean phosphorus concentration is 9.48 micrograms per litre, within the oligotrophic band, which extends to 10.

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 208 clarity readings at site 510/10 give a median Secchi depth of 4.8 meters.

Median Secchi depth by year at site 510/10

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

Bobs Lake Weather

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

Bobs Lake weather

Water temperature

No provincial monitoring station records water temperature on Bobs Lake. The LastLake model computes the temperature of its surface water for each day from the daily mean air temperature at Environment Canada’s Centreville climate station, 40 kilometers from the lake, or the next nearest station when its record is incomplete, and from the lake’s area of 2,904 hectares and its mean depth of 7.5 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 Bobs Lake carries the model’s figures for the past weeks and the coming week.

See also Lake Water Temperature in Ontario

Bobs Lake Water Level

Parks Canada measures the level of Bobs 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 Bobs Lake

Ontario’s aquatic resource records name 31 fish species in Bobs Lake. The province’s other records for the lake name two further species, muskellunge and splake. They appear in the records below.

Popular species in the province’s records

• Lake Trouttrout and whitefish
• Lake Whitefishtrout and whitefish
• Ciscotrout and whitefish
• Northern Pikepike
• Walleyeperch
• Yellow Perchperch
• Smallmouth Basssunfish
• Largemouth Basssunfish
• Black Crappiesunfish
• Rock Basssunfish
• Pumpkinseedsunfish
• Bluegillsunfish
• Burbotcod
• Brown Bullheadcatfish

Spawning areas

Ontario maps 52 fish spawning records within the Bobs Lake outline, for two different species, and all of them are mapped below.

By number of records

By area mapped

• Sunfish family44 areas4.1 ha
• Walleye8 areas0.8 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 Bobs Lake run from 1946 to 2010 and hold 96 releases. Walleye account for most of the fish: 5,510,188 released in sixteen of the years between 1947 and 2009. The last recorded release was 5,000 lake trout adults in 2010.

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for five species taken from Bobs Lake, tested for contaminants at a sampling location in Bedford Twp., Frontenac 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

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

Fisheries management zones around Bobs Lake

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

Bobs Lake Ice Fishing

An ice hut on Bobs 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). Bobs 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 Bobs 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

Getting on the water

Two access marks are mapped on Bobs Lake.

See also Boat Launches on Ontario Lakes

Islands and names

Bobs Lake contains 113 islands in the Ontario Hydro Network’s outline, seven of them over 10 hectares and 39 under a tenth of a hectare. Two of them lie mostly inside wetland the province’s Wetland With Significance dataset maps as marsh or unclassified wetland.

Official names

Ontario’s geographic names register lists 27 official names on the water and its islands: 20 islands and six bays. A further 4 named points stand on the mainland shore. The register records the origin of one name: Oak Island, “Refers to the mature oak trees that cover the island.”

Bays 6

• Buck Bay
• Crow Bay
• Green Bay
• Long Bay
• Mill Bay
• Mud Bay

Points on the shore 4

• Antoine Point
• Coutlee Point
• Elm Point
• Whiskey Point

Communities on the lake 2

• Bolingbroke
• Bradshaw

Nearby lakes

• Crow Lake5 km away
• Eagle Lake8 km away
• Desert Lake13 km away
• Sharbot Lake13 km away

All lakes

Questions about Bobs Lake

• How deep is Bobs Lake?

  Its deepest charted contour is 24.4 meters, and the water within it is deeper.

• How big is Bobs Lake?

  Its surface covers 29.1 square kilometers and it holds 113 islands. Of its 212 kilometers of shoreline, 143 kilometers is the mainland shore and 69 kilometers is the shore of the islands.

• What fish are in Bobs Lake?

  Ontario’s aquatic resource records name 31 species, among them lake trout, walleye, smallmouth bass, largemouth bass, northern pike and lake whitefish. The lake’s spawning, consumption and stocking records also name muskellunge and splake.

• Is there a public boat launch?

  Records mark one boat launch.