Protecting Our Lakes and Waterways: Understanding the Link Between Fertilizers and Blue-Green Algae

Published on June 1, 2026

Blue-green algae blooms, also known as cyanobacteria, have become an important environmental issue in several regions of Quebec. Their proliferation in lakes and waterways can affect water quality, aquatic ecosystems, and even limit certain recreational activities.

But did you know that lawn and garden fertilization practices can play a significant role in this phenomenon? Blue-green algae are microorganisms naturally present in water. However, they proliferate excessively when there is an overabundance of nutrients, mainly phosphorus and nitrogen.

These nutrients enter waterways, among other things, through surface runoff from residential, agricultural, and urban lands.

Fertilizers used to maintain lawns and gardens generally fall into two main categories: synthetic or organic.

  • Organic fertilizers release nutrients more slowly. They also improve the structure and overall health of the soil, which promotes more stable plant growth and reduces nutrient runoff into the environment.
  • Synthetic fertilizers are designed to provide plants with nutrients quickly. However, when applied excessively or before heavy rainfall, some nutrients may be washed into storm sewers and eventually into waterways. This excessive nutrient input directly contributes to the rapid growth of bluegreen algae.

Healthy soil acts as a natural filter. When rich in organic matter and well structured, it retains water and nutrients more effectively, reducing their transport into lakes and rivers.

Over time, more natural and balanced fertilization practices contribute not only to healthier gardens, but also to the protection of our water resources.

Protecting water quality is a shared responsibility. By adopting more sustainable gardening practices, every resident can help reduce the risk of blue-green algae blooms and preserve the health of our natural environments.

Together, we can make a lasting difference for our lakes, rivers, and future generations.

© Copyright Town of Baie-D'Urfé. All rights reserved. | Privacy policy
Top