Pink Lake is meromictic, meaning that its upper and lower layers of water never mix. Normally a lake’s water layers mix completely each year during the spring and fall, because of water density, water and air temperature, and the wind. The mixing of lake waters distributes nutrients and oxygen evenly throughout the lake.
Pink Lake’s waters do not mix, because it has a small surface and bowl-like shape, and is surrounded by steep cliffs that protect it from the wind. There is no oxygen in the deepest seven metres of the lake.
The magnificent greenish tint to the waters of Pink Lake is caused by the growth of microscopic algae. Even though it is spectacularly beautiful, it is very harmful. This vegetation gradually takes over the oxygen, suffocating the lake. This natural process, called “eutrophication,” can take many thousands of years.
Unfortunately, Pink Lake’s popularity with Park visitors over the years sped up this process. The algae were growing so rapidly that eutrophication would have taken only a few decades. To preserve the lake for future generations, we have rehabilitated the site by building platforms and a trail to limit the damage caused by erosion. Volunteers also helped plant 10,000 small trees.
With no oxygen at the bottom of Pink Lake, there is only one organism that lives in its depths: a prehistoric anaerobic organism. It is a pink photosynthetic bacterium, which uses sulphur instead of oxygen to transform sunlight into energy.
Pink Lake is also home to the three-spined stickleback fish, a saltwater fish left behind from the Champlain Sea, which used to cover the region. This little saltwater fish adapted to the lake’s gradual desalination and today lives in the lake’s fresh water.
You can do your part to preserve Pink Lake by staying on the trail, and by not picking flowers or capturing animals. Dogs and pets are not permitted on the Pink Lake Trail.
Help us protect Gatineau Park and leave no trace.
For more information see Gatineau Park’s visitor information.