Lièvre WatershedLievre River. Source: COBALIUntil 1993 the practice of floating logs down the Lièvre River was big business. Unfortunately, as the logs floated in the water the residue of wood and bark began to break down - this had a detrimental effect on the river's water quality as it increased the biochemical oxygen demand (BOD), i.e. it reduced the concentration of oxygen in the water.

Wood and bark are made of organic substances (lignin and tannin) and nutrients (nitrogen and phosphorus). The tannins and lignin cause the water to become dark (a yellow-brown colour) in some places where there are a lot of logs.

However, the effects and impact of these organic substances on the water quality are difficult to quantify. In 2002, the Advisory Committee on managing the Lièvre River (CCGRL) organized an initiative to harvesting the floating logs which remain in the river. 150 cords of wood were removed from the river in the Val-des-Bois area, in St. Aimé-du-Lac-des-Iles. Not all of the logs were removed, and many remain at the bottom of the river and on the shoreline.