Conestogo Lake

Where Conestogo Lake is

Conestogo Lake lies in the County of Wellington, within the Township of Mapleton.

How deep is Conestogo Lake?

The deepest mapped contour on Conestogo Lake is 24.0 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 86 depth contours for Conestogo 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.

No monitoring site on Conestogo Lake is registered with the Lake Partner Program, so no phosphorus or clarity record exists for the lake.

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.

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

Conestogo Lake Weather

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

Conestogo Lake weather

Water temperature

Ontario’s aquatic resource records class Conestogo Lake as a cool-water lake, with a mean depth of 9.5 meters against its maximum of 24.

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 Conestogo Lake. The LastLake model computes the temperature of its surface water for each day from the daily mean air temperature at Environment Canada’s Elora Rcs climate station, 27 kilometers from the lake, or the next nearest station when its record is incomplete, and from the lake’s area of 614 hectares and its mean depth of 9.5 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 Conestogo Lake carries the model’s figures for the past weeks and the coming week.

See also Lake Water Temperature in Ontario

Fish in Conestogo Lake

Ontario’s aquatic resource records name 13 fish species in Conestogo Lake. The province’s other records for the lake name one further species, black crappie. It appears in the records below.

Popular species in the province’s records

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

Spawning areas

Ontario maps 3 fish spawning records within the Conestogo Lake outline: 3 northern pike spawning areas covering 18.18 hectares.

By number of records

By area mapped

• Northern Pike3 areas18.2 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.

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for eight species taken from Conestogo Lake, tested for contaminants at a sampling location in Maryborough Twp., Wellington 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. 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 16

Conestogo Lake lies in Fisheries Management Zone 16. Ontario sets its fishing seasons and catch limits by zone. The province describes it as a zone of large river systems, with Lake Simcoe and Lake Couchiching its large lakes, carrying important recreational and tourism fisheries under high fishing effort.

Fisheries management zones around Conestogo Lake

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

Conestogo Lake Ice Fishing

An ice hut on Conestogo 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). Conestogo Lake lies within FMZ 16.

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 16 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 Conestogo 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

Conestogo Lake contains two islands in the Ontario Hydro Network’s outline, of 0.5 hectares, none of them named in the province’s register.

Nearby lakes

• Lake Belwood32 km away
• Puslinch Lake49 km away
• Lake Eugenia72 km away
• Chesley Lake103 km away

All lakes

Questions about Conestogo Lake

• How deep is Conestogo Lake?

  Its deepest charted contour is 24 meters, and the water within it is deeper.

• How big is Conestogo Lake?

  Its surface covers 6.1 square kilometers and it holds 2 islands. Of its 43 kilometers of shoreline, 42 kilometers is the mainland shore and 1 kilometer is the shore of the islands.

• What fish are in Conestogo Lake?

  Ontario’s aquatic resource records name thirteen species, among them walleye, smallmouth bass, largemouth bass, northern pike and yellow perch. The lake’s spawning, consumption and stocking records also name black crappie.