Farlain Lake

Where Farlain Lake is

Farlain Lake lies in the County of Simcoe, within the Township of Tiny.

How deep is Farlain Lake?

Farlain Lake reaches a maximum recorded depth of 5.4 meters, determined from 7,369 soundings.

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.

Farlain Lake 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.

The longest record is held by site 6967/4 at Mid Lake, deep spot, sampled over 19 springs to 2025. Its long-term mean phosphorus concentration is 9.63 micrograms per litre, within the oligotrophic band, which extends to 10. The site’s 55 clarity readings give a median Secchi depth of 3.0 meters.

Water temperature

Ontario’s aquatic resource records class Farlain Lake as a cool-water lake, with a mean depth of 1.7 meters against its maximum of 5.4.

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 Farlain Lake. 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.

Satellite thermal imagery gives a surface reading on clear days: the Landsat sensors pass over Farlain Lake 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.

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 Farlain Lake

Ontario’s aquatic resource records name 13 fish species in Farlain Lake. The province classes the lake as cool water. The record took effect on 14 October 2010, and it compiles what field biologists had reported by then.

Nine of the thirteen species in the province’s records

• Muskellungepike
• Walleyeperch
• Yellow Perchperch
• Smallmouth Basssunfish
• Largemouth Basssunfish
• Black Crappiesunfish
• Rock Basssunfish
• Pumpkinseedsunfish
• Brown Bullheadcatfish

Stocking history

Ontario’s stocking records for Farlain Lake run from 1946 to 1970 and hold 24 releases. Walleye account for most of the fish: 4,570,000 released in seven of the years between 1948 and 1956. The last recorded release was 2,000 largemouth bass fingerlings in 1970.

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

Eating the fish

The 2025 Guide to Eating Ontario Fish carries consumption advice for three species taken from Farlain Lake, tested for contaminants at a sampling location in Tiny Twp., Simcoe 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

Fisheries Management Zone 16

Farlain Lake lies in Fisheries Management Zone 16. Ontario sets its fishing seasons and catch limits by zone. Zone 16 is the most southerly inland zone in the province and takes in all of southwestern Ontario, with Toronto, Mississauga, Hamilton, Kitchener-Waterloo and London. 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.

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 Farlain Lake.

Farlain Lake Ice Fishing

An ice hut on Farlain Lake must be removed by March 15. Farlain Lake lies in fisheries management zone 16, 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 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.

When the ice comes and goes

No ice record is kept on Farlain Lake. The province’s nearest long record covers eight lakes near Dorset, about 94 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.

Ice conditions

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

Nearby lakes

• Gloucester Pool21 km away
• Six Mile Lake21 km away
• Healey Lake38 km away
• Morrison Lake41 km away

All lakes

Questions about Farlain Lake

• How deep is Farlain Lake?

  Its maximum recorded depth is 5.4 meters.

• How big is Farlain Lake?

  Its surface covers 1.1 square kilometers, with 7 kilometers of shoreline.

• What fish are in Farlain Lake?

  Ontario’s aquatic resource records name thirteen species, among them walleye, smallmouth bass, largemouth bass, muskellunge, yellow perch and black crappie.

• Is the water clear?

  The one monitoring site with a phosphorus status is classified oligotrophic, the clearest of the province’s three bands.