Lake Scugog General

2020 Information about Lake Scugog

This has been a very hard year for Lake Scugog. The winter presented us with little snowpack in the woods to create a strong spring ‘freshette.’ We entered spring without soil in the watershed being totally saturated. While the months of March, April, May were cloudy and cold, there was not significant rainfall. Then starting in June we had almost two and one-half months of sunshine and 30 degree days. Evaporation from our 68 sq. km. water surface and warm (sometimes over 80F) and shallow water took our water level down significantly — a level that was not improved much by a number of rain events and slightly cooler weather in August.

Slowly the lake is also filling in caused by a wide range of factors including shoreline erosion, stormwater runoff from land, high concentrations of ‘dirt’ from the air and most of all decomposition of huge quantities of hybrid Eurasian Watermilfoil and now the invasive alga, starry stonewort.

Lake Scugog is aging, — rapidly. We must all co-operate to prevent as much silt and sediment from entering the lake from eroding shorelines (see an appropriate shoreline edge at left) by protecting  appropriately and by planting buffers of deep rooted native plants to absorb the nutrients. We must keep new invasive species from entering the lake through Clean, Draining and Drying our boats both before and after we boat on the lake. We must keep our septic systems and leach fields working appropriately and pump them regularly. Over all, we must prevent as many nutrients as possible from entering the lake — no fertilizers!!!

General Information

Lake Scugog is a large shallow lake which can be found about one hour to the east of the city of Toronto, Canada. There are several major cities within a short driving distance with Oshawa to the south, Peterborough to the east and Lindsay to the north.  The historic town of Port Perry is on the lake’s south-west shore.

Lindsay Dam
Dam at Lindsay, open for spring runoff.

Water enters the lake from many sources, mainly the Nonquon River, Blackstock Creek, Cawker’s Creek and the Cartwright wetlands.  It is also fed by general runoff and from many springs along its shorelines and under its surface.

Water from Lake Scugog flows north through the Scugog River to Sturgeon Lake.  From there it travels through the Trent-Severn Waterway to the other Kawartha lakes and out to Lake Ontario.  It is possible to boat from Lake Scugog over to Lake Simcoe or down to Lake Ontario through this Waterway and its system of locks.

A navigational level of 250 m. above sea level is maintained by a dam in Lindsay built in the 1830’s which raised the lake approximately six feet.  See the topic THE DAM AT LINDSAY for more information and contacts regarding its operation. Water cannot be stored behind the dam for later use.

 Size of the watershed 533.7 sq. km.
Size of lake surface area:   68 sq. km.
Shoreline length: 172 km.
Scugog Island shoreline   30.6 km.
Seasonal lake fluctuation 20 to 50 cm.
Average depth: 1.4 m.
Greatest depth:  7.6 m.

Lake Scugog, especially the West side, is considered a “eutrophic” lake in that it has, because of its age and other factors, an excess of the nutrients nitrogen and phosphorus.  This is true more so on the shallow west arm of the lake than the east arm.  The east arm can reach depths of up to 23 ft. and does not receive as much urban run off.  Because of the excess of nutrients, its shallow nature and its generally soft lake bottom, Lake Scugog has many aquatic plants.  In order to reduce the level of nutrients, Scugog Township undertook and is currently implementing the Lake Scugog Environmental Management Plan and the Port Perry Stormwater Management Plan.  Also, the new Port Perry Water Pollution Control Plant on the upper Nonquon River, completed in 2017, has reduced both nitrogen and phosphorus outputs from the Nonquon River to the lake to zero, or negligible amounts.

Dam and Locks at Lindsay

See our section https://scugoglakeste


Suspended filamentous algae in Lake Scugog

Since Lake Scugog is rich in nutrients, it is to be expected that it will produce algae. Algae are a diverse group of microscopic organisms (see our YouTube video) that depend on energy from the sun and nutrients from the water to grow and proliferate. They range from the huge stands of salt water seaweed found on the west coast down to the tiny unicellular types that sometimes turn our lake a turbid green.

There are hundreds of different kinds of algae in Lake Scugog. Some are present only at particular times of the year. They are critically important to life in our lake ecosystem.  They are the basis of the food chain because they take the energy from the sun and turn it into a form that can be used by higher forms of life in the lake such as bugs, crayfish and fish.

The most common form of algae in our lake is filamentous. These stringy types start out in early spring either free floating as shown or attached to surfaces of plant material. Later they detach and rise to the surface where they are transported to shorelines to form large mats.

Recently, a new alga has appeared and is proliferating in our lake .  It is called Starry Stonewort. You will hear much more about this type of algae in the next years but you can watch our video about it at

Are clumps of filamentous algae unhealthy?  Should the water be clear?

Algal mats in Kent Bay

No, not necessarily. Most filamentous green algae do not produce toxins that are harmful to humans. The algae thrive on nutrients that have washed into the water. Excessive growth of algae may indicate that there are other pollutants that also have been washed into the water. If the source of nutrients is pet, animal or bird waste, it is likely that bacteria and other pathogens are living on the algae mats. See our video: Microcystic Blue Green Algae.

Algae found near stormwater outlets, or in ponds, should not be handled because there may be harmful bacteria associated with it. If homeowners do handle algae in these areas, they should wash their hands thoroughly or use sanitizer. Algal growth serves as Nature’s way of capturing nutrients and contaminants. Having some algae in the water helps to capture contaminants and protect water quality. The clumps are unsightly, but they are not themselves a threat to your health.

Lake Scugog is considered a ‘jewel in the crown of Scugog’.  The Scugog Lake Stewards and the Township’s approximately 24,000 residents recognize its importance to their economy, to their real estate values but most of all to the quality of their life. The best way to protect it is to do everything possible to restrict new nutrient loads from entering the lake.