Excessive use of fertilizers and subsequent nutrient runoff impact water everywhere, including locally. When fertilizer is applied to a lawn, nutrients are being added – something that all plants need to survive and grow.  What might not be obvious, though, is that the soil may already have sufficient levels of these nutrients for plants to be strong and healthy.  Brand-new lawns or areas with very poor soils might lack nutrients, but most established lawns have enough nutrients.  When healthy, well-established lawns are fertilized anyway, the nutrients (mainly nitrogen and phosphorus) that aren’t used by the grass run off with the next rain and end up in our streams and reservoirs where they can feed algae and create other problems.

When too much fertilizer enters the water, it can cause the natural process of eutrophication to speed up. Eutrophication causes algae growth to explode. Algae typically have a very fast life cycle, and when this life cycle is accelerated it causes problems for water quality and aquatic life, primarily by depleting oxygen from the water. This phenomenon, known as hypoxia, results in oxygen levels becoming so low that the water can no longer support aquatic life. The end result is a dead zone like the one in the Gulf of Mexico.