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Basic Information
What is the Problem? | What is EPA's National Nutrient Policy? | What are EPA and the States Doing? | Glossary
What is the Problem?
Eutrophication, the prolific growth of algae in summer months.
Like the human body, water bodies require nutrients, such as nitrogen and phosphorus, to be healthy, but too many nutrients can be harmful. Many of our nation's waters, including streams, rivers, wetlands, estuaries, and coastal waters, are affected by nitrogen and phosphorus pollution. The effect of nitrogen and phosphorus pollution for a given water body depends on its ecoregion and its sources of nitrogen and phosphorus.
High levels of nitrogen and phosphorus in waters can produce harmful algal blooms. In turn, these blooms can produce "dead zones" in water bodies where dissolved oxygen levels are so low that most aquatic life cannot survive. This condition in water bodies is referred to as hypoxia.
Here are some things that contribute to nitrogen and phosphorus pollution:
- Overusing fertilizer (both residential and agricultural usage)
- Rainfall flowing over cropland, Animal Feeding Operations and pastures, picking up animal waste and depositing it in water bodies
- Rainfall flowing over urban and suburban areas where stormwater management is not required (e.g., parking lots, lawns, rooftops, roads)
- Discharge of nitrogen and phosphorus from waste-water treatment plants
- Overflow from septic systems