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Sierra Club Water Sentinels

Nitrogen & Phosphorus Pollution

Like the human body, water bodies require nutrients such as nitrogen and phosphorus. But too many nutrients can be harmful. Many of our nation's rivers, streams, wetlands, estuaries, and coastal waters are adversely affected by nitrogen and phosphorus pollution.

Eutrophication is the process by which a body of water acquires high concentrations of nutrients, especially phosphates and nitrates, which promote excessive growth of algae. As the algae die and decompose, oxygen levels in the water are depleted, killing aquatic plant life, fish and shellfish. Many algae also produce toxins that are harmful and sometimes fatal to humans, animals, and fish.

Areas of water with low concentrations of oxygen are called dead zones. These exist in almost every coastal waterway, including the Gulf of Mexico, Chesapeake Bay, Long Island Sound, and the coasts of Oregon and Washington. The Gulf of Mexico dead zone is as large as the state of Massachusetts. Many inland waterways also have dead zones. Lake Erie's dead zone now encompasses nearly the entire lake.

Through our water testing and advocacy, the Water Sentinels promote practices that protect wetlands, reduce fertilizer use and storm water runoff, and establish pollution control standards for nitrogen & phosphorus.

Some things that contribute to nitrogen and phosphorus pollution include:

  • Overusing fertilizer (both residential and agricultural usage)
  • Rainfall flowing over cropland, Factory Farms 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
  • Loss of wetlands

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