Synonyms: Nitrogen, Phosphorus, Eutrophication

In the topic of stormwater, nutrients most often refer to nitrogen and phosphorus. Nitrogen and phosphorus occur naturally in nearly all environments and ecosystems and are critical to the growth and health of plant species. Fertilizers are used to increase nitrogen and phosphorus levels on your lawn, in your garden, or in agricultural production.

When levels of these nutrients become too high, due to excess fertilizing or waste entering streams, they can have detrimental effects on water quality and stream ecosystems.  Because of this, reducing nitrogen and phosphorus (along with fine sediments) are the main targets in the discussion of how to improve water quality.

Nutrient enrichment causes eutrophication in streams, lakes, rivers, bays, and the ocean. In simple terms, eutrophication is a process that:

  1. Expedites the growth of phytoplankton and algae growth in a water body, known as an algae “bloom”
  2. The “bloom” overtakes other natural plant species and interferes with fish and micro-organism habitats
  3. The “bloom” can accelerate the growth of invasive species and reduce biodiversity
  4. The “bloom” uses the temporarily available nutrients and then dies off
  5. The dead algae sinks to the bottom of water bodies and undergoes decomposition
  6. Bacteria in decomposition converts the previously used nutrients into inorganic forms, which are toxic to humans, fish, and wildlife
  7. Decomposition also use great amounts of dissolved oxygen, which in turn, suffocates and kills fish and organisms in water bodies
  8. Decomposition will cloud the water and, in some cases, induce foul smelling odor

Substantial human additions to nitrogen and phosphorus levels in water bodies can turn once-vibrant ecosystems into toxic dead zones.  It is important to consider the potential and lasting effects when fertilizing your lawn or garden. Consider using native plants, which require minimal amounts of artificial fertilizer. Also be sure to review the Lawn and Garden Care webpage on this site to learn how you can achieve a beautiful lawn and garden while reducing your impact on local water quality!