Located south of the city of Shawinigan, Quebec, and encompassing 6,600 hectares (16,309 acres), the Lac-à-la-Tortue Bog is the largest bog in the St. Lawrence Valley. It was formed several thousand years ago by a branch of the Saint-Maurice River. Bogs are wetlands in which peat forms and accumulates over time from dead plants, particularly sphagnum mosses, but also other types of moss, sedges and woody plants. This specific bog contains several ponds and swamps that are home to a variety of unique plant species including orchids and carnivorous plants, water birds like black duck, wood duck, great blue herons, and blue-winged teal, and a number of mammals and reptiles. The Lac-à-la-Tortue bog is a particular type of bog, with a raised centre, fed only by rainwater and snowmelt. It is characterized by an acidic pH and by mineral content supplied exclusively through precipitation.

Bogs and other types of wetlands are important ecosystems. In addition to habitat for plants and animals, they provide many ecological services, particularly by absorbing large quantities of water during heavy rainfall or rapid snowmelt. The Lac-à-la-Tortue bog contributes to improving water quality by filtering fine sediment and processing nutrients. Furthermore, it plays an important role in mitigating climate change by capturing and storing 4.7 megatons of carbon.

More than three quarters of the bog are currently protected by the Nature Conservancy of Canada (NCC) and the Government of Quebec. The bogs of Centre-du-Québec and Mauricie are often subject to drainage interventions for forestry purposes. Prior to the protection of the Lac-à-la-Tortue bog, a network of drainage ditches was created to lower the water table and promote forest growth. This has affected the land’s capacity to hold water and deliver related benefits to nature and communities. To remedy this, NCC plans to restore proper water storage functions to the bog by installing dikes across the ditches and filling them with local soil. Its teams will carefully monitor the results to assess the effect on the water table and the bog’s ecological functions.