Parc de la Gatineau (Pink Lake Trail)

Pink Lake
A Unique Treasure that Must Be Protected
Pink Lake, because of its unique characteristics, is a treasure of Gatineau Park. Of rare beauty, the site offers the opportunity to relax while learning about its ecology. The interpretation panels are waiting for you...

Why Call a Green Lake “Pink”?
In spite of its name, this lake is not pink. It inherited its name from a family who settled in the region in 1826. The Pinks, who were from Ireland, cleared their lot and grew potatoes, corn and wheat. Part of the property still belongs to their descendants, though most is now part of Gatineau Park. The Pink family has given its name not only to a lake but also to a road and a cemetery.

What Exactly Is a Meromictic Lake?
In most lakes, the water mixes completely each year during the spring and fall, under the influence of water density, water and air temperature, and the wind; nutrients and oxygen are distributed evenly.

However, because of its sheltered position (surrounded by steep cliffs that protect it from the wind) and its shape (small surface area, average depth and bowl-like shape), the lake’s waters do not mix. This is why it is called “meromictic.” Of particular note is the fact that the deepest seven metres of the lake remain without oxygen.


Life in the Lake
In the depths of the lake, an anaerobic prehistoric organism has been able to survive. It is a pink photosynthetic bacterium that uses sulphur instead of oxygen when it transforms sunlight into energy. To maximize the amount of light it captures, without being in contact with oxygen, the colony forms a dense layer that floats seven metres from the bottom.

After the glaciers melted, the region was covered by an arm of the Atlantic Ocean: the Champlain Sea. When it retreated it left the three-spined stickleback. This little saltwater fish (three to five centimetres long) adapted slowly to the lake’s gradual desalination. In fact, it adapted so well that today it lives in the fresh water of the lake. Desalination usually takes about thirty years. However, Pink Lake is fed only by runoff waters (unique in its watershed area), and so its desalination took place over three thousand years!

History in the Sediments
Apart from the pink bacteria, there are no other life forms in the layer where there is no oxygen because they cannot survive. Anything that falls to the depths of the lake will not decompose, but remains at the bottom, undisturbed. By analyzing a sample of the deposits, we can find out about such important facts as:

the forests that surrounded the lake
the concentration of lead in the air
forest fires
Why Is Pink Lake Green?
No, it’s not polluted. However, like any life form, lakes get older. A lake dies when invaded with vegetation that usurps oxygen and suffocates it. Slowly, algae, tall weeds and trees replace the animal life. This natural process called “eutrophication” (plant growth caused by a strong concentration of nutrients) can stretch out to many thousands of years.

However, when sped up by human activity, a lack of balance sets in, endangering the present wildlife. Unknowingly, we came by the hundreds to enjoy the site, to swim and picnic… without realizing that the erosion of the banks caused by these activities was putting natural fertilizer into the lake, which promoted rapid algae growth. The algae proliferated to the extent that eutrophication would have taken only a few decades if efforts to rehabilitate the lake had not been undertaken recently. Ironically, it’s that proliferation of microscopic algae that gives the magnificent greenish tint to the waters. Even though it’s spectacularly beautiful, it is very harmful.

What Should We Do?

Now that we are better informed, we know how to respect our environment. In the past, some mistakes have been made. We’ll have to take this as a lesson if we want to leave our treasures for future generations. To help, we have rehabilitated the site by building some platforms and a unique trail to limit the damage caused by erosion. Volunteers also helped plant 10,000 small trees. And you can do your part. By staying on the trail and by not picking flowers or capturing animals, you will help our “patient.” Its life is no longer in danger, but it is still in intensive care!

*Domestic animals are not permitted on Pink Lake trail.