Basic Information on Nutrient Pollution

Información relacionada disponible en español

It’s important to understand nutrient pollution because it has affected many of our water bodies and other aspects of environmental health, human health and the economy.

What is Nutrient Pollution?

Nutrient pollution is caused by too much nitrogen and phosphorus entering the air and water, usually from a wide range of human activities. Nitrogen and phosphorus are nutrients that are natural parts of aquatic ecosystems. Nitrogen is also the most abundant element in the air we breathe. Nitrogen and phosphorus support the growth of algae and other aquatic plants, which provide food and habitat for fish, shellfish and smaller organisms that live in water.

The Challenges of Nutrient Pollution

Too much nitrogen and phosphorus in the water causes algae and algae-like bacteria to grow faster than ecosystems can handle, forming algal blooms. Significant increases in algae harm water quality, food resources and habitats, and decrease the oxygen that fish and other aquatic life need to survive. Algal blooms can severely reduce or eliminate oxygen in the water, leading to fish illnesses or deaths, often in large numbers. Some blooms consist of cyanobacteria that mimic algae in their appearance and ecological role. They can release toxins into the water that can make people and animals sick if they touch, drink, or eat contaminated fish or shellfish from the water.

Nutrient contamination in ground water - which millions of people in the United States use as their drinking water source - can be harmful, even at low levels. Infants are vulnerable to a nitrogen-based compound called nitrates in drinking water.

Excess nitrogen in the atmosphere can produce pollutants such as ammonia and ozone, which can impair our ability to breathe, limit visibility and alter plant growth. When excess nitrogen comes back to earth from the atmosphere, it can harm the health of forests, soils and waterways.

• The Sources

  Sources such as agriculture and stormwater can contribute excess nutrients to our environment.

  Learn about sources

• The Effects

  Nutrient pollution can affect human and animal health, as well as the environment and the economy.

  Understand the effects

• Where Nutrient Pollution Occurs

  Nutrient pollution affects air and water and can impact all types of water bodies.

  Learn where it occurs