Lake Scugog

Where Lake Scugog is

Lake Scugog lies in the Regional Municipality of Durham, with shoreline in the Township of Scugog and the City of Kawartha Lakes.

How deep is Lake Scugog?

The deepest mapped contour on Lake Scugog is 6.1 meters, and the water within that boundary descends even farther. Ontario’s bathymetry record holds 7 depth contours for Lake Scugog.

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.

Lake Scugog has 10 Lake Partner monitoring sites. Six have reported phosphorus for the three or more years the province requires before a status is assigned. Two of those sites are classified mesotrophic and four eutrophic.

The longest record is held by site 6922/12 at Viewlake-deep spot, sampled over 16 springs to 2025. Its long-term mean phosphorus concentration is 22.55 micrograms per litre, within the eutrophic band, which begins at 20. The site’s 93 clarity readings give a median Secchi depth of 0.9 meters.

Water temperature

Ontario’s aquatic resource records class Lake Scugog as a warm-water lake, with a mean depth of 1.37 meters against its maximum of 6.1.

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 Lake Scugog. 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 Lake Scugog 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 Lake Scugog

Ontario’s aquatic resource records name 41 fish species in Lake Scugog. The province classes the lake as warm water. The record took effect on 6 March 2023, and it compiles what field biologists had reported by then. The province’s other records for the lake name one further species, brook trout. It appears in the records below.

Twelve of the 42 species in the province’s records

• Muskellungepike
• Walleyeperch
• Yellow Perchperch
• Smallmouth Basssunfish
• Largemouth Basssunfish
• Black Crappiesunfish
• Rock Basssunfish
• Pumpkinseedsunfish
• Bluegillsunfish
• Brown Bullheadcatfish
• Common Carpminnow
• Lake Sturgeonother

Spawning areas

Ontario maps 72 fish spawning records within the Lake Scugog outline, for four species, all of them mapped areas.

By number of records

By area mapped

• Largemouth Bass25 areas35.8 ha
• Muskellunge23 areas61.9 ha
• Smallmouth Bass12 areas12.1 ha
• Walleye12 areas9.3 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 Lake Scugog run from 1946 to 1989 and hold 94 releases. Muskellunge account for most of the fish: 2,228,450 released in 34 of the years between 1946 and 1989. The last recorded release was 1,950 muskellunge fingerlings in 1989.

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

Eating the fish

The 2025 Guide to Eating Ontario Fish carries consumption advice for twelve species taken from Lake Scugog, tested for contaminants at a sampling location in Durham R.M. 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 17

Lake Scugog lies in Fisheries Management Zone 17. Ontario sets its fishing seasons and catch limits by zone.

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.

Where a row reads zone-wide, the zone’s own season or limit above applies.

Lake Scugog Ice Fishing

An ice hut on Lake Scugog must be removed by March 1. Lake Scugog lies in fisheries management zone 17, 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 17 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 goes out

The ice has been recorded leaving Lake Scugog in 93 springs between 1901 and 1995. The median date is April 11. The earliest recorded break-up is March 15 in 1983, and the latest is April 29 in 1904 and 1972.

Across the 93 recorded springs the median date has moved by less than a day each decade.

The record was contributed by Peter J. Dillon, Ontario Ministry of the Environment to the Global Lake and River Ice Phenology Database. It holds the day the ice left and carries no date for the day it formed, so it says nothing about when Lake Scugog freezes.

Ice conditions

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

Islands and names

Lake Scugog contains eighteen islands in the Ontario Hydro Network’s outline, none of them named in the province’s register. Fifteen of them lie inside wetlands mapped in the province’s Wetland With Significance dataset. The largest two, of 17.5 and 6.1 hectares, fall inside the Lake Scugog Marsh (Osler Marsh) and East Cross Creek No.15 wetlands.

The province’s register names five further islands on Lake Scugog, which the outline draws joined to the shore: Scugog Island, Washburn Island, Seven Mile Island, Platten Island and Birch Island.

Official names

Ontario’s geographic names register lists 2 official names on the water and its islands: two bays. A further 6 named points stand on the shore.

Bays 2

• King's Bay
• Starr Bay

Points on the shore 6

• Ball Point
• Pine Point
• Plum Point
• Scugog Point
• Stephenson Point
• Williams Point

Nearby lakes

• Sturgeon Lake33 km away
• Cameron Lake41 km away
• Pigeon Lake43 km away
• Mitchell Lake44 km away

All lakes

Questions about Lake Scugog

• How deep is Lake Scugog?

  Its deepest charted contour is 6.1 meters, and the water within it is deeper.

• How big is Lake Scugog?

  Its surface covers 66.5 square kilometers and it holds 18 islands. Of its 155 kilometers of shoreline, 149 kilometers is the mainland shore and 6 kilometers is the shore of the islands.

• What fish are in Lake Scugog?

  Ontario’s aquatic resource records name 41 species, among them walleye, smallmouth bass, largemouth bass, muskellunge, yellow perch and black crappie. The lake’s spawning, consumption and stocking records also name brook trout.